Broome Regional Resource Recovery Park

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Broome Regional Resource Recovery Park
Broome Regional Resource
Recovery Park
Stakeholder Engagement Summary
Prepared for Shire of Broome
March 2015
Project Number TW14014
Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Talis Consultants Pty Ltd
8/663 Newcastle St
Leederville WA 6007
Ph: 1300 251 070
www.talisconsultants.com.au
ABN: 85 967 691 321
DOCUMENT CONTROL
Version
Description
Date
Author
Reviewer
0a
Internal Review
5/3/15
RPC
JK
1a
Released to Client
31/3/15
RPC
JK
Approval for Release
Name
Position
File Reference
John King
Director
TW14014 – Stakeholder
Engagement Summary
Signature
Copyright of this document or any part of this document remains with Talis Consultants Pty Ltd and cannot be
used, transferred or reproduced in any manner or form without prior written consent from Talis Consultants Pty
Ltd.
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Table of Contents
1
2
Introduction ............................................................................................................................... 1
1.1
Background ............................................................................................................................. 1
1.2
Site Selection Study Process .................................................................................................... 1
Engagement Summary ............................................................................................................. 2
2.1
3
Stakeholder Engagement ....................................................................................................... 2
2.1.1
Stakeholder Engagement Process ...................................................................................... 2
2.1.2
Stakeholder Engagement Feedback ................................................................................. 2
Discussion and Future Works ................................................................................................... 13
Tables
Table 2-1: Site Selection Criteria Stakeholder Feedback
Table 2-2: Key Stakeholder Feedback Summary for Areas of Interest
Figures
Figure 1: Areas of Interest
Appendices
Appendix A: Stakeholder Feedback Letters
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Month YYYY
1
Introduction
1.1
Background
The Shire of Broome (the Shire) owns and operates the Buckley Road Waste Management Facility
(the Buckley Road Facility) located approximately 9km from the town of Broome. The Buckley Road
Facility is licenced (Licence No. L6912/1997/11) pursuant to the Environmental Protection Act 1986
under the following Prescribed Premise categories:


Category 61 – Liquid Waste Facility; and
Category 64 – Class II putrescible landfill site.
The current landfill at the site is approaching the end of its operational lifespan. To allow for the
continuation of the current waste disposal services, the Shire has begun the process of identifying a
new Preferred Site to locate a Regional Resource Recovery Park (RRRP).
Previous investigations undertaken by the Shire over recent years have not been able to determine a
site suitable for detailed site investigations. The Shire has commissioned Talis Consultants Pty Ltd
(Talis) to undertake a Site Selection Study, including community and stakeholder consultation, with
the objective of selecting a site based on best practice principles that warrants further consideration
for the establishment of a RRRP.
As part of the Site Selection Study, Talis and the Shire produced an Engagement Strategy to guide
the process for engaging and consulting with key stakeholders and the greater Broome community.
This report details the consultation with stakeholders in relation to selection criteria used to determine
a Preferred Site and the identification of Areas of Interest for the site.
1.2
Site Selection Study Process
The key phases in the delivery of the RRRP are as follows:





Phase 1: Siting and Consultation;
Phase 2: Detailed Site Investigation for Preferred Site(s);
Phase 3: Design and Approvals;
Phase 4: Tender and Construction; and
Phase 5: Operations.
The siting and consultation phase involves the following tasks:










Advice to public and stakeholders of the study process and objectives;
Preparation of Site Selection Criteria;
Stakeholders consultation on Site Selection Criteria;
Identification of Areas of Interest;
Stakeholder and community consultation on Areas of Interest:
Identification of Sites of Interest;
Identification of Preferred Sites (x2);
Stakeholder and community consultation on Preferred Sites;
Adoption of Preferred Sites by Council; and
Onsite investigations of Preferred Sites.
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Stakeholder Engagement Summary
Shire of Broome
Month YYYY
2
Engagement Summary
As outlined in the Shire’s Community Engagement Framework, engagement is to be carried out with
key stakeholders and the community.
2.1
Stakeholder Engagement
Key stakeholders were chosen based on their level of direct interest and responsibilities within the
study area. Other parties were identified as stakeholders, but with a general interest in the project,
rather than a specific interest in the study area.
2.1.1 Stakeholder Engagement Process
Stakeholder engagement began by broadly informing the stakeholders of the need for the RRRP as
a replacement for the current landfill and the scope of the Site Selection Study. Stakeholders
involved at this commencement phase consisted of:







Aboriginal groups;
Community and environmental groups;
Private industry;
Industry bodies;
Local Governments;
State Government; and
Federal Government.
Information was communicated to stakeholders through the Council website and printed media. In
addition to the above, key stakeholders with direct interest in the Site Selection Criteria, mostly as
approval agencies for the project, were consulted to provide feedback on the suitability of the
criteria for the project. The following groups were involved during this stage:






State Government Agencies;
Federal Government Agencies;
Nyamba Buru Yawuru Ltd;
Goolarabooloo Millibinyarri Indigenous Corporation;
Roebuck Bay Working Group Inc; and
Australasian Wader Studies Group and Global Flyway Network.
2.1.2 Stakeholder Engagement Feedback
Feedback was obtained from key stakeholders on the suitability of the Site Selection Criteria for the
project. Table 2-1 below provides a summary of the initial feedback received from the key
stakeholders.
Table 2-1: Site Selection Criteria Stakeholder Feedback
Stakeholder
Department
of Aboriginal
Affairs
Feedback



221 Registered Aboriginal Heritage places within Shore of Broome.
Recommended that Talis familiarise themselves with Due Diligence Guidelines.
Recommended that Talis contact local Aboriginal groups to inform them of the
proposed project.
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Stakeholder Engagement Summary
Shire of Broome
Month YYYY
Stakeholder
Department
of Agriculture
and Food
Department
of
Environment
Regulation
Department
of Mines and
Petroleum
Department
of Planning
Department
of Water
Feedback

No concerns - happy to participate in the Study




Supports a lined Class III landfill.
Encourages community consultation.
Suggests referral to EPA.
Requested that due consideration be given to EPA's Guidance Statement No. 3
separation distances with a recommended buffers of 500m to sensitive land
uses, 135m to single residences and 35m internal boundary buffer.
Recommends consideration of the following as part of the Site Selection
Criteria:
o Flora and Fauna;
o Prevailing winds;
o Visual Amenity;
o Consideration of required space, buffers and distance to market;
o Other potential uses for the Site; and
o Post closure options for site.
The Geological Survey of Western Australia is willing to participate and assess
sites on behalf of the DMP with respect to impacts on access to mineral and
petroleum resources, geothermal energy and basic raw materials.


Requested that consideration be given to:
 Any existing Native Title claim / determination / Indigenous Land Use
Agreements;
 Listed Declared Rare Flora and potential impact on Ramsar wetlands;
 The location of Browse LNG Precinct / new Airport; and access to electricity and
water services.
 Happy to provide further advice relating to surface and groundwater issues
associated with the Sites of Interest.
Department

of State
Development
No comment on Criteria but looking forward to be kept informed on progress
Department
of Lands
Emphasised that Native Title will be a key factor while undertaking assessment

This feedback was factored into the Areas of Interest report and will also be given ongoing
consideration throughout the Site Selection Process.
Following consideration of the above feedback, the Areas of Interest report was then revised and
released to the community for comment. Appendix A contains the original copies of stakeholder
submissions while Table 2-2 below summarises the comments based on each Area of Interest.
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Table 2-2: Key Stakeholder Feedback Summary for Areas of Interest
Area of
Interest
Stakeholder
Goolarabooloo Millibinyarri
Indigenous Corporation

Culturally inappropriate.
Nyamba Buru Yawuru Ltd

No comments.

Area A is 8km from potential coastal groundwater dependent ecosystems with depth to
groundwater ranging from 30 to 60m.
The area has poorly defined non-perennial surface drainage which should be considered
and further investigated.
Department of Water

Department of Parks and Wildlife

Could affect adjacent freshwater springs within the Yawuru Conservation Estate.
Department of Planning

Emphasised need to consider Local Planning Scheme.


No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
No mining tenure, no recorded mining prospects, covered by petroleum application STP-EPA0094.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Culturally inappropriate.
Nyamba Buru Yawuru Ltd

Concern regarding proximity to Willie Creek wetland.
Department of Aboriginal Affairs
Area A
Feedback
Department of Mines and
Petroleum



Department of Environment
Regulation


Water Corporation
Roebuck Bay Working Group Inc
Area B
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Stakeholder Engagement Summary
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Area of
Interest
Stakeholder

Considered unsuitable due to its proximity to potential groundwater dependent ecosystems
and/or shallow depth to groundwater.
Department of Parks and Wildlife

Could affect adjacent freshwater springs within the Yawuru Conservation Estate.
Department of Planning

Emphasised need to consider Local Planning Scheme.


No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
No mining tenure, no recorded mining prospects, covered by petroleum application STP-EPA0094.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Culturally inappropriate.
Nyamba Buru Yawuru Ltd

Considered unacceptable.

Northern part of Area C considered unsuitable due to its proximity to potential groundwater
dependent ecosystems and/or shallow depth to groundwater.
Southern part of Area C has a separation distance to licenced groundwater users and
groundwater dependent ecosystems between 4 and 6km.
The depth to groundwater is 30 to 40m.
Further investigations in this Area should be as far east as possible.
Consideration to be given to the distance from rural residential properties using minimally
Department of Water
Department of Aboriginal Affairs
Area B
Feedback
Department of Mines and
Petroleum



Department of Environment
Regulation


Water Corporation
Roebuck Bay Working Group Inc
Area C

Department of Water
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
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Area of
Interest
Stakeholder
Feedback
treated groundwater for their drinking water.
Department of Parks and Wildlife

Located in a parcel of land which is to become part of the Yawuru Conservation Estate.
Department of Planning

Emphasised need to consider Local Planning Scheme.


No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
No mining tenure, no recorded mining prospects, covered by petroleum application STP-EPA0094.
The RRRP is not considered to be a compatible land use with the current zoning of this area of
land.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Culturally inappropriate.
Nyamba Buru Yawuru Ltd

Water Corporation Reserve.

Has a separation distance to licenced groundwater users and groundwater dependent
ecosystems between 4 and 6km.
The depth to groundwater is 30 to 40m.
Further investigations in this Area should be as far east as possible.
Consideration to be given to the distance from rural residential properties using minimally
treated groundwater for their drinking water.
Department of Aboriginal Affairs
Department of Mines and
Petroleum



Area C
Department of Environment
Regulation



Water Corporation
Roebuck Bay Working Group Inc
Area D
Department of Water
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Area of
Interest
Stakeholder
Feedback
Department of Parks and Wildlife

No comments.
Department of Planning

Emphasised need to consider Local Planning Scheme.


No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations. Local Aboriginal groups should be informed, and suggest Aboriginal Heritage
surveys be conducted.
No recorded mining prospects, but cuts the north-western corner of exploration licence
application E04/2357.
Area D is covered by State Agreement petroleum title EP 436 and therefore needs to be
referred to the Department of State Development.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Culturally inappropriate.
Nyamba Buru Yawuru Ltd

Concern regarding proximity to the Kurin area and Dampier Creek wetlands.

Considered unsuitable due to its proximity to potential groundwater dependent ecosystems
and/or shallow depth to groundwater.
Department of Parks and Wildlife

Has a direct effect on the values of nearby conservation areas by attracting predatory birds.
Department of Planning

Emphasised need to consider Local Planning Scheme.

No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
Department of Aboriginal Affairs

Department of Mines and
Petroleum
Area D


Department of Environment
Regulation


Water Corporation
Roebuck Bay Working Group Inc
Department of Water
Area E
Department of Aboriginal Affairs
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
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Area of
Interest
Stakeholder
Feedback
Department of Mines and
Petroleum



Department of Environment
Regulation

Area E


Water Corporation
Roebuck Bay Working Group Inc

Chris Hassell – Australasian
Wader Studies Group and Global
Flyway Network
Suggests strongly that Area E is unsuitable due to it attracting a large number of birds of prey
close to internationally protected migratory shorebird roosts on the north shores of Roebuck
Bay.
Goolarabooloo Millibinyarri
Indigenous Corporation

Natural hunting grounds.

Subject to exclusive possession native title requiring negotiation of terms and consent from
Yawuru Common Law Native Title Holders.
Concerns that these sites may affect wetlands.
Similar separation distance as Area H (5 to 7km) however Area F is within the Skuthorpe
groundwater sub-area boundary.
Locating the RRRP in Area F could cause issues for groundwater monitoring and Department
of Water prefers that the RRRP is not situated in this area.
Nyamba Buru Yawuru Ltd
Area F


No mining tenure, no record of mining prospects.
This area is covered by petroleum title EP 473, which is not a State Agreement petroleum title.
The proximity of Area E to the listed Dampier Creek important wetland has a bearing on the
suitability of Area E for a future RRRP.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.
A number of objections to a RRRP being located at Area E due to its proximity to Dampier
Creek Nationally Important Wetland and Roebuck Bay Ramsar Wetland.
Department of Water



Department of Parks and Wildlife

No comments.
Department of Planning

Emphasised need to consider Local Planning Scheme.

No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
Department of Aboriginal Affairs
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
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Area of
Interest
Stakeholder
Feedback



No mining tenure, no recorded mining prospects.
This area is covered by State Agreement petroleum title EP 436 and therefore needs to be
referred to the Department of State Development.
The area is bounded on the eastern side by File Notation Area (FNA) 7672, the proposed path
of the Great Northern Pipeline Project; but this should be of little concern as this area of
interest would most likely be accessed from the northern side (Broome Road).
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Has potential but requires further studies, particularly ground water.

Subject to exclusive possession native title requiring negotiation of terms and consent from
Yawuru Common Law Native Title Holders.
Concerns that these sites may affect wetlands.
Is at least 10.5km from a receptor, has no identified water courses and depth to groundwater
is 10 to 20 metres.
Department of Mines and
Petroleum


Area F
Department of Environment
Regulation


Water Corporation
Roebuck Bay Working Group Inc
Nyamba Buru Yawuru Ltd
Department of Water
Area G


Department of Parks and Wildlife

No comments.
Department of Planning

Emphasised need to consider Local Planning Scheme.

No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
No mining tenure, no recorded mining prospects.
This area is covered by State Agreement petroleum title EP 436 and therefore needs to be
Department of Aboriginal Affairs
Department of Mines and
Petroleum
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
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Area of
Interest
Stakeholder
Feedback

referred to the Department of State Development.
The area is bounded on the southern side by FNA 7672, the proposed path of the Great
Northern Pipeline Project. If the pipeline is constructed, access to this site would need to cross
the pipeline, requiring an engineered truck crossing.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Natural hunting grounds.

Subject to exclusive possession native title requiring negotiation of terms and consent from
Yawuru Common Law Native Title Holders.
Concerns that these sites may affect wetlands.
Has 5 to 7km separation distance from wetlands, distance to groundwater is 12 to 22 metres,
no surface water sources are present and consideration should be given to pastoral bores.


Department of Environment
Regulation
Area G


Water Corporation
Roebuck Bay Working Group Inc
Nyamba Buru Yawuru Ltd
Department of Water
Area H


Department of Parks and Wildlife

No comments.
Department of Planning

Emphasised need to consider Local Planning Scheme.

No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations. Local Aboriginal groups should be informed, and suggest Aboriginal Heritage
surveys be conducted.
No comment but assumed to be the same as Area J: No mining tenure, no recorded mining
prospects.
This area is covered by State Agreement petroleum title EP 436 and therefore needs to be
referred to the Department of State Development.
The area is bounded on the northern side by FNA 7672, the proposed path of the Great
Department of Aboriginal Affairs

Department of Mines and
Petroleum


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Stakeholder Engagement Summary
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Area of
Interest
Stakeholder
Feedback

Northern Pipeline Project. If the pipeline is constructed, access to this site would need to cross
the pipeline, requiring an engineered truck crossing.
Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Goolarabooloo Millibinyarri
Indigenous Corporation

Too close to a creek.

Subject to its exclusive possession native title requiring negotiation of terms and consent from
Yawuru Common Law Native Title Holders.
Concerns that these sites may affect wetlands.
Considered unsuitable due to its proximity to potential groundwater dependent ecosystems
and/or shallow depth to groundwater.

Department of Environment
Regulation


Area H
Water Corporation
Roebuck Bay Working Group Inc
Nyamba Buru Yawuru Ltd
Department of Water
Area J


Department of Parks and Wildlife

No comments.
Department of Planning

Emphasised need to consider Local Planning Scheme.

No known registered Aboriginal heritage sites or Other Heritage Places within the proposed
locations.
Local Aboriginal groups should be informed, and suggest Aboriginal Heritage surveys be
conducted.
No mining tenure, no recorded mining prospects.
This area is covered by State Agreement petroleum title EP 436 and therefore needs to be
referred to the Department of State Development.
The area is bounded on the northern side by FNA 7672, the proposed path of the Great
Northern Pipeline Project. If the pipeline is constructed, access to this site would need to cross
the pipeline, requiring an engineered truck crossing.
Department of Aboriginal Affairs



Department of Mines and
Petroleum
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Area of
Interest
Stakeholder
Feedback


Request advice on whether there is provision of space for liquid waste acceptance for the
projected life of the RRRP.
Stormwater and Leachate ponds will need to be sufficiently sized to account for extreme
rainfall events and to maximise evaporation.
Unable to support any of the Areas of Interest located in proximity to the Broome Water
Reserve until further studies have been undertaken to demonstrate that a proposed RRRP will
not jeopardise the quality of Broome’s primary public drinking water source area.
Engage in public consultation process as part of the site selection process.

No comments.
Chris Hassell – Australasian
Wader Studies Group and Global 
Flyway Network
No comments.
Department of Environment
Regulation
Area J


Water Corporation
Roebuck Bay Working Group Inc
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Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
3
Discussion and Future Works
As shown in Table 2-2, Area E received some valuable feedback regarding birds of prey and their
proximity to national and internationally protected areas. In addition to this, there was also concern
regarding the proximity to other environmental and social sensitive areas. Based on the feedback
received, it was deemed that Area E was too disadvantaged for the location of the RRRP, and as
result should be removed from further studies.
While the remaining Areas of Interest do possess some disadvantages, there are a number of
advantages that warrant their inclusion in future studies. The next phase of the project will be to
determine Sites of Interests from within these Areas of Interest. The feedback received from
stakeholders and the community will be considered in determining these Sites of Interest.
Following the evaluation of Sites of Interest, the Sites of Interest Report will be prepared. A Multi
Criteria Analysis methodology will be used to rank the Sites of Interest from least to most preferred.
The stakeholder feedback summarised in this report, together with the feedback received from the
community, will be used in the scoring of each Site of Interest.
The Sites of Interest Report will seek to identify at least two Preferred Sites that warrant further
consideration. The Sites of Interest Report will be published for community and stakeholder
comment and then presented to Council for adoption. Detailed studies of the Preferred Sites such
as Aboriginal Heritage Surveys, Hydrological studies, Geotechnical Studies and Environmental Surveys
will then be undertaken. The results of the detailed findings will be utilised to determine the final
location for the RRRP.
TW14014 - Stakeholder Engagement Summary.1a
March 2015 | Page 13
Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Figures
Figure 1: Areas of Interest
TW14014 - Stakeholder Engagement Summary.1a
March 2015
410,000
420,000
430,000
440,000
450,000
460,000
470,000
8,050,000
400,000
8,050,000
390,000
8,040,000
8,040,000
Area A
Area D
GREAT NORTH ER N
HWY
Area F
Area J
ME RD
Area H
8,020,000
BRO O
8,020,000
8,030,000
Area G
BROO
ME -
8,030,000
Area C
CAPE LEVEQUE RD
Area B
Area E
AB
CREE
K
NO
RT
HE
RD
8,010,000
CR
EA
T
390,000
400,000
410,000
420,000
430,000
440,000
Areas of interest
460,000
¤
Broome
Access Road
Port
Hedland
Regional Distributor
Primary Distributor
470,000
AREAS OF INTEREST
Broome Site Selection Study - RRRP
Road network (MRWA)
Local Distributor
HW
Y
450,000
LEGEND
Study area
RN
8,010,000
G
R
0
800
Kilometres
0
2.5
5
10
15
20
Kilometers
Coordinate System: GDA 1994 MGA Zone 51
Projection: Transverse Mercator, Datum: GDA 1994, Units: Meter
Scale @ A3: 1:225,000 Prepared:
Date:
29/10/2014 Checked:
Revision:
Rev B Reviewed:
R Cullen Project No:
TW14014
J Botterill
Figure 1
N King
Document Path: \\server\Talis\SECTIONS\Waste\PROJECTS\TW2014\TW14014 - Broome Site Selection\GIS\Maps\Areas of Interest\TW14014_008_Cadastre_wAreas.mxd
Broome Regional Resource Recovery Park
Stakeholder Engagement Summary
Shire of Broome
Appendix A: Stakeholder Feedback
Letters
TW14014 - Stakeholder Engagement Summary.1a
March 2015
From: RIDGE, Kevin
Sent: Thursday, 2 October 2014 10:57 AM
To: '[email protected]'
Cc: '[email protected]'
Subject: Regional Resource Recovery Park-Site Selection Study Broome Shire Council Your Ref MDK
RRP01
Dear Michael,
I have just received a copy of your letter dated 12 September 2014.
The Geological Survey of Western Australia (GSWA) is willing to participate in this study to identify
potential site for the Regional Resource Recovery Park (RRRP).
The GSWA will assess these sites on behalf of the Department of Mines and Petroleum (DMP) with
respect to access to mineral and petroleum resources, geothermal energy and basic raw materials.
I have just left a message on your phone and my contact details here at the GSWA are listed below.
Regards,
Kevin
Kevin Ridge | Senior Geologist
Resources, Geological Survey
Department of Mines and Petroleum
100 Plain Street East Perth WA 6004
Tel: +61 8 9222 3144 | [email protected]
www.dmp.wa.gov.au
DISCLAIMER: This email, including any attachments, is intended only for use
by the addressee(s)
and may contain confidential and/or personal information and may also be
the subject of legal privilege.
If you are not the intended recipient, you must not disclose or use the
information contained in it.
In this case, please let me know by return email, delete the message
permanently from your system and destroy any copies.
Before you take any action based upon advice and/or information contained
in this email you should
carefully consider the advice and information and consider obtaining
relevant independent advice.
From: Gustavsson, Cate [mailto:[email protected]]
Sent: Thursday, September 25, 2014 10:49 AM
To: [email protected]
Cc: Michael Dale; Welch , Nicholas
Subject: Regional Resource Recovery Park - Site Selection Study
Hi John,
Further to our telephone discussion today, please find below a number of items you may wish to
consider in developing the site selection criteria.
Please consider under: "Planning attributes" any existing Native Title claim / determination / ILUAs;
"Environmental attributes" listed DRF and potential impact on RAMSAR (Bird strike);
"Location - Separation distances from sensitive receptors" consider the location of Browse LNG
Precinct / new Airport; and "Access to Services" access to electricity and water.
Please give me a call if you would like to discuss further.
Kind Regards
Cate
Cate Gustavsson | Principal Planning Officer - Kimberley
Regional Planning And Strategy | Department of Planning
Unit 23, 39 Carnarvon Street (PO Box 3643) | Broome WA 6725
T (08) 9194 4949 | F (08) 6551 9001 | M 0457 550 309
E [email protected] | W www.planning.wa.gov.au
DISCLAIMER
This email and any attachments are confidential and may contain legally privileged
and/or copyright material. You should not read, copy, use or disclose any of the
information contained in this email without authorisation. If you have received it in
error please contact us at once by return email and then delete both emails. There is
no warranty that this email is error or virus free.
From: ZAMIR, Marzia [mailto:[email protected]]
Sent: Thursday, October 16, 2014 3:07 PM
To: Michael Dale
Subject: Ref: MDGK RRP01 Regional Resource Recovery Park - Site Selection Study
Dear Mr. Dale
Thank you for inviting the Department of State Development to provide feedback on the site
selection criteria for the new Regional Resource Recovery Park.
We look forward to being kept informed of the Shire’s progress with the Site Selection Study.
Kind regards
Marzia Zamir | Senior Project Officer
Strategic Industrial Lands, State Initiatives
Department of State Development
1 Adelaide Terrace East Perth WA 6004
Tel: +61 8 9222 0494 | [email protected]
www.dsd.wa.gov.au
th
18 International Conference & Exhibition on Liquefied Natural Gas
11 – 15 April 2016
Perth Convention and Exhibition Centre
Perth, Western Australia, Australia
Website: www.lng18.org
DISCLAIMER: This email, including any attachments, is intended only for use
by the addressee(s)
and may contain confidential and/or personal information and may also be
the subject of legal privilege.
If you are not the intended recipient, you must not disclose or use the
information contained in it.
In this case, please let me know by return email, delete the message
permanently from your system and destroy any copies.
Before you take any action based upon advice and/or information contained
in this email you should
carefully consider the advice and information and consider obtaining
relevant independent advice.
Yawuru Native Title Holders Aboriginal Corporation RNTBC ICN 7033
55 Reid Road PO Box 425 BROOME WA 6725
Ph: (08) 9,929600 Fax: (08) 9,9296io email: [email protected] org. au
11 December 201.4
Kerin Donohoe
Chief Executive Officer
Shire of Broome
PO Box 44
BROOME WA 6725
By Email: [email protected] wa. gov. au
Dear Kenn,
REGIONAL RESOURCE RECOVERY PARK - SITE SELECTION
We refer to the preliminary submission which was made by Yawuru Native Title Holders Aboriginal
Corporation (Yawuru RNTBC) dated 1.4 November 2014 about the Shire's proposed Regional Resource
Recovery Park (RRRP).
The Yawuru RNTBC Board considered the matter of the RRRP at its meeting on 3 December 201.4. We thank
Talis Consultants and Michael Dale of the Shire for their attendance at the board meeting, which allowed for
constructive discussion about the project.
Cultural and environmental considerations
Yawuru's preliminary submission has already provided high-level comments on the nine areas of interest
identified in Talis' RRRP site selection study.
The Yawuru RNTBC Board has emphasised that cultural and environmental factors should be paremount in
the selection of the site. As already flagged with the Shire, Yawuru will need to conduct cultural heritage
surveys at the Shire's cost in order to ascertain the suitability of the proposed sites. The surveys are intended
to determine any potential impacts of a RRRP on native title, cultural sites and objects, culturalIy significant
flora and fauna, and any other culturalIy significant natural resources and values.
Talis have indicated that cultural heritage surveys should be done at the front end of the site selection
process, prior to other studies being carried out. Yawuru supports this approach and remains ready to discuss
the necessary arrangements for surveys with the Shire.
Commercial negotiations and opportunities
As you are aware, the Roebuck Plains pastoral lease will soon be transferred from the Indigenous Land
Corporation to NYamba Buru Yawuru Ltd (NBY). Yawuru people hold exclusive possession and occupation
native title over the area of Roebuck Plains Station.
Page I of 2
Yawuru RNTBC and NBY are willing to further investigate possible tenure and commercial options to enable
the RRRP to be located on Roebuck Plains. We are also keen to discuss employment, business and other
opportunities that may be available to Yawuru people through the RRRP project.
The location of the RRRP on Roebuck Plains would be subject to, and would need to be consistent with, the
outcomes of cultural heritage surveys.
We welcome the opportunity to further discuss these matters with you.
Yours sincerely,
^
2.1
Tony Lee
General Manager Community Programs
cc
Michael Dale
Director Engineering Services
Page 2 of 2
55 Reid Rd PO Box 425 BROOME WA 6725
Ph: o8,919z 9600 Fax: o8.919z 9610
.j. ,^. C~' ^,
email: ya. wu, [email protected] 1.0rg, an
ABNs 87,373069,7
NYAAABA BURU YAWURU LTDin.
14 November 2014
Our Reference: FAH029-97558
Your Reference: MDGK RRPO, ./
Mr Michael Dale
Director of Engineering Services
Shire of Broome
By Email: Michael. dale broome. wa. ov. au
Dear Michael
RE: REGIONAL RESOURCE RECOVERY PARK SITE SELECTION STAKEHOLDER CONSULTATION
We refer to the Site Selection Survey Report for the proposed Regional Resource Recovery Park ("RRRP
Report") produced by Talis Consultants and presented to stakeholders on 12 November 2014 ("Consultation
Meeting")
This letter constitutes a preliminary submission on behalf of Yawuru Native Title Holders Aboriginal
Corporation RNTBC ("Yawuru RNTBC"). Please note that this submission is subject to further consultation
being undertaken directly with the Yawuru RNTBC Board (currently planned for 3 December 20.41 and on a
full heritage assessment process being undertaken on prospective sites.
We are concerned that the RRRP Report lists nine prospective sites when, in previous consultations between
the Shire of Broome and Yawuru RNTBC and NBY, it had been strongly indicated that there were only five
prospective sites currently on the table.
We also understand from the Consultation Meeting that ground studies, including heritage surveys, are not
expected to be carried out until20, .5. This is contrary to the position previously agreed between the Shire of
Broome and NYamba Buru Yawuru Ltd that heritage surveys (of the five prospective sites) would be
undertaken in November 201.4. In addition, the consultants indicated ideal Iy the size of the areas would be
125ha and Yet your conversations with us have indicated area size of 200ha.
With respect to the nine areas identified in the RRRP Report, we have the following preliminary comments:
Area A
this area is outside of the Yawuru Determination Area and we have no direct comments.
Area B
this area is outside of the Yawuru Determination Area. However, we would be very concerned
that any development in that area - particularly something in the nature and scope of the RRRP,
could have an impact on the Willie Creek wetlands nearby, Willie Creek is both ecological Iy and
culturalIy significant and there are freshwater springs in the area marked
Area C
although currently uriallocated crown land, this area is within the Yawuru Conservation Estate
agreed to by the State of Western Australia and the Shire of Broome in the 201.0 Yawuru PBC
ILUA. It will in the future become conditional freehold held by NYamba Buru Yawuru Ltd for the
purposes of conservation and traditional use. It is unacceptable as a site for the proposed RRRP.
Area D
this area is part of the Water Corporation's reserve.
Area E
We would have grave concerns about a development of this nature in this area, due to its
proximity to both the highly cultural Iy sensitive Kunin area and to the ecologicalIy significant
Dampier Creek wetlands and subsequent impact that it would have on the wider Roebuck Bay.
Areas
We would consider there to be some constraints in this area, given the reservation of the
F, G, H
"Skuthorpe" land north of Area F for agricultural development, impacts on the Roebuck
and J
Roadhouse and so forth. More importantly, these areas are all subject to exclusive possession
native title and are part of the Roebuck Plains Pastoral lease, which is in the process of being
transferred to NYamba Buru Yawuru. Any surrender of pastoral lease land and any surrender or
suppression of native title would only occur after negotiations for appropriate terms and is subject
to the informed consent of the Yawuru Common Law Native Title Holders. Furthermore there are
concerns of the potential for such a facility here to affect adversely the wetlands which have
significant cultural and hunting significance for Yawuru.
As You are aware, it will be essential that any prospective site is subjected to a thorough Cultural Impact
Assessment by Yawuru to determine whether there are any issues that are not discernable through aerial
photography. Given that most of the areas identified are wholly undisturbed tor minimal Iy disturbed) we
advise that this should occur before other ground studies (such as Beotechnic) as it is possible that those
activities may riot be permissible in some locations within the identified areas.
As noted above, a supplementary submission is highly likely to be made by Yawuru after the consultation with
the Yawuru PBC Board.
If You have any questions please contact Caitlin Fegan on 0891929626 or Caitlin fe an
Yours sincerely
^.., ^:,
Tony Lee
General Manager - Community Programs
,
awuru. or .au
Michael Dale, Chief Engineer
Broome Shire Council
PO Box 44 | Broome | WA | 6725
8 9191 3456 |
[email protected]
December 11, 2014
Dear Mr Dale,
The Roebuck Bay Working Group Inc (RBWG) is providing comments on Areas of Interest
Summary Report for a Broome Regional Resource Recovery Park (BRRRP). In this letter,
RBWG outlines significant objections to Site E being considered for the proposed BRRRP.
RBWG also recommends the need to cover the new facility to reduce populations of
scavenging birds, and facilities to be built in Broome to reduce illegal dumping of rubbish.
As you know, Roebuck Bay is internationally recognised as an area of high conservation
value. The Bay is a globally significant Ramsar site (Ramsar Convention on Wetlands of
International Importance) and is also recognised through National Heritage listing for
outstanding indigenous, environmental and paleontological values. Hundreds of thousands
of birds utilise the Bay each year as part of the East Asian Australian Flyway; a flyway which
has more shorebird species than any other flyway in the world. Roebuck Bay also has the
highest diversity of invertebrate marine life of all the tropical mudflats so far studied in the
world, the second largest known population of snubfin dolphin (Orcaella heinsohni) and
provides significant foraging and breeding habitat for cultural significant species including
turtles and dugongs.
LEACHING OF NUTRIENTS AND CONTAMINANTS INTO AQUIFER AND ROEBUCK BAY
Site E is between 3 - 5 km from the Roebuck Bay Ramsar site and close to Dampier Creek
headwaters, both of which are included in the soon to be announced Yawuru Nagulagun
Roebuck Bay Marine Park. During the wet season, Site E is likely to be within 100 m of the
Dampier Creek floodplain. Given this proximity, an open faced landfill facility at Site E poses
an unacceptably high risk of contamination from leachates (nutrients, chemicals, endocrine
disruptors) entering the Ramsar listed Wetland, especially during large rain events and
spring tides.
As RBWG have previously outlined to the Broome Shire, Roebuck Bay’s exceptional
biodiversity and cultural values are currently being threatened by wastewater discharge and
subsequent blooms of Lyngbya majuscula. This issue is well documented as impacting the
soon to be announced Yawuru Nagulagun Roebuck Bay Marine Park.
Research undertaken by the University of Western Australia (led by Associate Professor
Ryan Vogwill) has identified the connection between wastewater disposal and nutrient
enrichment through the Broome aquifer. Their research shows nutrient loads in Roebuck
Bay are currently well above ANZEEC water quality guidelines. Moreover, their stormwater
surveys have identified elevated nutrient loads entering the bay during the seasonal first
flush of the system after the onset of the wet season. For example, the nutrient loads from
stormwater have been measured as a total nitrogen load of 550 kg/year and the total TP
load of approximately 90 kg/year. The shock loading, which occurs over the first month of
the wet season, is 450 kg/year total nitrogen and 75g/year total phosphorous. These figures
are based on those measured in the 2012 wet season. These are unacceptably high and
pose significant threat to the natural and cultural values of the Bay. A new facility at site E
will undoubtedly add to these very high nutrient loads through the runoff from impervious
surfaces constructed at the site as well as leaching of organic and inorganic resources into
the aquifer and the Bay.
There are also the additional risks of polluted and or nutrient enriched runoff from
impervious surfaces constructed at the site and risk of leaching and contaminants from
dams and stormwater catchment areas into the aquifer (which is already overwhelmed with
nutrients) and Roebuck Bay. Given this, building the BRRRP at Site E poses an unacceptable
risk to natural and cultural values of the Bay.
ELEVATED NUMBERS OF RAPTORS AND SHOREBIRD SURVIVAL
Studies have shown the constraining factor for shorebird survival in Roebuck Bay is
disturbance on high tide roosting sites (Rogers, Hassell & Lewis; Rogers, Piersma & Hassell).
One aspect of disturbance, is birds of prey flying over high tide roosts and unsettling birds.
Shorebirds expend extra energy to avoid these raptors, and due to the amount of weight
they need to put on for their migratory flights, they can expend too much energy and be
unable to migrate. A small number of raptors flying over the birds is natural; artificially high
number of raptors disturbing the shorebirds will have a profound, negative effect.
It is well documented there are artificially high numbers of raptors such as black kites
(Milvus migrans) and whistling kites (Haliaster sphenurus) sighted over Broome Waste
Management Facility (BWMF) on Buckley Road. Counts at BWMF by the Broome Bird
Observatory (BBO) on June 27, 2013, reveal over 1,300 black kites and in July 2014 over 600
black kites (BBO data pers. comm.). Local ornithologist George Swan recorded over 2,500
black kites in September 2011 at the same location. These numbers are an order of
magnitude larger than exist in ‘natural’ settings such as exists around Roebuck Bay. The
BRRRF located at Site E will provide a level of attraction for birdlife well above natural levels
and therefore presents an unacceptable level of disturbance to protected species (JAMBA,
CAMBA, ROKAMBA).
In addition to the environmental consequences of choosing Site E for the future BRRRP, this
site is within 9 km of the site proposed for a new airport. As bird strike is a significant
hazard to for aircraft, having a facility such as the RRRP sited within 9 km from an airport is a
serious safety issue and should not be considered.
SILVER GULL PROBLEM FOR ALL AREAS UNDER CONSIDERATION
As there has been no mention of covering the BWWWP with netting or burying organic
waste immediately, the RBWG is very concerned about the impacts of increasing numbers
of Silver Gulls (Larus novaehollandiae), and their impact on seabird breeding colonies and
turtle rookeries in Roebuck Bay, Eighty Mile Beach, Cable Beach and off shore islands.
In the late 1980’s, Silver Gulls, were an uncommon species in Broome. George Swann, a
local ornithologist who has been leading Kimberley Birdwatching tours in the region for 21
years, has noted a substantial increase in the population of Silver Gulls in Broome over the
last 25 years. His surveys at the BMWF show numbers have increased from 200 in January
1996 to thousands of birds in 2014 (see count data below). It is thought the increased
availability of food for Silver Gulls at the BWMF is the main contributing factor to the rapid
increase in the population of Silver Gulls.
There is growing evidence the Silver Gulls that forage at the BWMF are significantly
impacting seabird breeding colonies and turtle rookeries on the Lacepede Islands (Class A
Nature Reserve) and Adele Islands (Class C Nature Reserve). Banding studies show that
Silver Gulls banded in Broome nest on the Lacepede Islands. Observers at these islands have
noted that, when breeding, Silver Gulls feed on other seabird chicks and turtle hatchlings.
For example, as early as 1996, George observed on the Lacepede Islands, a group of Silver
Gulls excavating the surface of a turtle nest as hatchlings were emerging. George watched
without interference all the hatchlings being predated by the gulls. Silver Gulls were also
observed at night, predating sea turtle hatchlings making their way to the ocean.
As the population of Silver Gulls is artificially high because of their ability to forage at the
BMWF whilst not breeding, the RBWG believe it is imperative that the proposed BWWWP
(wherever it is built) must be designed to prevent Silver Gulls from accessing artificial food
sources and ponded water. This likely means covering the ponds and tip face with exclusion
netting and burying loads of organic waste immediately.
NEED FOR SUBSTATIONS IN BROOME
At present, there are significant amounts of rubbish being dumped in stormwater drains,
the bush and coastal environs around Roebuck Bay. Not only is this unsightly, this rubbish
contributes to the nutrient loading problems faced by the Bay. With the siting of BRRRP
likely to extend further out of town than the current BWMF, RBWG expect this illegal
dumping of rubbish will increase unless there are appropriate mitigation measures put in
place. We suggest there be small town drop off sites for this rubbish which can then be
moved in bulk to the new BRRRP facility on a regular basis.
Please contact the Roebuck Bay Working Group Inc to discuss any of these issues further.
Yours sincerely,
Roebuck Bay Working Group Inc
Shorebird disturbance in Roebuck Bay 2005-2006
Shorebird disturbance on the beaches of Roebuck Bay, 2005-2006:
Conservation implications and recommendations.
A report by Broome Bird Observatory for the WA Department of Conservation and Land
Management, NHT and the Shorebird Conservation Project / WWF-Australia.
Danny Rogers1, Chris Hassell2, Jan Lewis3
1
340 Nink’s Rd, Victoria 3761, Australia. [email protected]
Turnstone Nature Discovery. PO Box 3089, Broome, WA 6725
3
Broome Bird Observatory, PO Box 1313, Broome WA 6725
2
1
Shorebird disturbance in Roebuck Bay 2005-2006
Contents
Item
Page
Number
1. Summary
3
2. Introduction
4
3. Methods
3.1 Project organisation
3.2 Data collection
3.3 Analysis
6
6
6
9
4. Results
4.1 Variables influencing disturbance levels
4.2 Causes of disturbance
4.3 Human use of the northern beaches
4.4 Costs of disturbance, and are levels increasing?
10
10
15
18
24
5. Discussion
28
6. Conclusions and Recommendations
30
7. Acknowledgements
31
8. References cited
32
Appendix 1. Datasheets used
33
Appendix 2. Disturbance data compilation
37
Appendix 3. Statistical details
39
2
Shorebird disturbance in Roebuck Bay 2005-2006
1.
Summary
Roebuck Bay, on the shores of North-western Australia, is an internationally important
area for a number of migratory shorebird species. These small to medium-sized birds
(sandpipers, plovers and allies) nest in the northern hemisphere and migrate annually to
non-breeding sites such as Roebuck Bay. Australia has ratified a number of international
shorebird conservation treaties and has a legal obligation to protect migratory shorebirds
and their habitats.
The shorebirds of Roebuck Bay are specialised to feed on intertidal mudflats at low
tide. At high tide rising waters force the birds from their feeding grounds to sites known as
roosts. The beaches along the northern shores of Roebuck Bay are particularly important
roost sites, and previous studies have shown that they are the only daylight roosting option
available for shorebirds in the north of the bay when weather conditions are dry and tides
are between 6 and 8.2 m high (i.e. on about half of the daytime high tides in the bay).
Shorebirds on the northern beaches of Roebuck Bay experience high levels of
disturbance. This is potentially of conservation concern, because of the lack of alternative
roost sites, and because migratory shorebirds face tight energy budgets; if too much
energy is used up at roost sites it may become impossible to shorebirds to build up the
stores required for migration. Modelling of the energetic costs of shorebirds in Roebuck
Bay indicates that excessive roost disturbance could easily cause population declines.
Broome Bird Observatory carried out a study of disturbance on the northern
beaches or Roebuck Bay from May 2005 to April 2006, co-ordinating a team of volunteers
who twice a month recorded disturbance levels systematically at five beaches. Causes of
disturbance were identified, and human use of the northern beaches was also
investigated.
The study confirmed that disturbance levels are high. Controlling for a number of
factors that influence disturbance levels, a multivariate analysis showed that disturbance
levels are highest in the dry season from about May to August. Disturbance levels have
increased slightly since a previous study carried out from 1997 to 2000. The main cause of
disturbance was birds of prey, but people were also a major cause of disturbance.
A large proportion of the beach-users at Roebuck Bay were local residents; they
and tourists visited the bay for a variety of reasons, with fishing predominating. Birdwatching, cultural activities (over half of the Broome residents visiting the bay identified
themselves as Aboriginal) and sight-seeing were also important activities. Beach-walkers
caused a disproportionate amount of shorebird disturbance, but beyond that, no one
activity could be identified as more intrusive than any other. However, all activities caused
some disturbance. Most of this disturbance was unintentional. In general beach-users
were not well informed about the importance of the northern beaches as roost for
shorebirds, and were thus unaware of the damage that can be caused by disturbance.
We consider the disturbance levels on the northern beaches to be worrying, but not
yet critical because disturbance levels are only dangerously high from May to August, a
time of year at which shorebird populations are naturally low. We make a number of
recommendations to limit shorebird disturbance on the northern beaches. In the short
term we propose that Crab Creek road shuld remain unsealed; working with Yawuru
traditional owners to limit vehicle access onto beaches away from recognised boat ramps;
continued monitoring of disturbance levels and also of birds of prey; and more public
education about conservation of shorebird roosts. If these measures do not reduce
shorebird disturbance levels over the next three years, more intrusive measures to control
shorebird disturbance may be required, notably engineering works or re-routing of roads to
restrict human access. Such actions would carry the risk of causing public resentment, and
would require extensive consultation.
3
Shorebird disturbance in Roebuck Bay 2005-2006
2.
Introduction
Roebuck Bay is world-renowned as an important non-breeding site for migratory
shorebirds (van de Kam et al. 2003). These small to medium sized birds
(sandpipers, plovers and allies) nest at high latitudes in the northern hemisphere,
and migrate annually to non-breeding grounds thousands of kilometres away. Many
shorebird species are specialised to feed on intertidal flats at low tide during their
non-breeding period, and thus have restricted non-breeding ranges. Roebuck Bay is
one of the premier non-breeding sites for shorebirds in Australia. Only two sites in
Australia hold larger numbers of shorebirds, and none have such a high diversity of
shorebirds occurring in internationally important numbers. By ratifying a number of
international conservation agreements designed to (e.g. Ramsar, JAMBA, CAMBA),
Australia has accepted an obligation to protect migratory shorebirds and their
habitats, notably through compliance with the Environment Protection and
Biodiversity Conservation Act 1999.
This report focuses on the conservation of shorebird roosts on the northern beaches
of Roebuck Bay. Roost studies in Roebuck Bay over the last few years have
demonstrated that these beaches are of considerable conservation importance. They
hold large numbers of shorebirds, and on tides of intermediate height (about 6.0 to
8.2 m) they are the only potential roost site that can be used by shorebirds in the
north of Roebuck Bay.
The northern beaches of Roebuck Bay are well known to people in the Broome
region, and they are often visited by birdwatchers, anglers and other people. The
town of Broome, on the north-west shores of Roebuck Bay, is growing rapidly, and
this likely to increase levels of human visitation to Roebuck Bay. Humans on the
beaches of Roebuck Bay can cause disturbance to shorebirds, and previous studies
of disturbance on the beaches of Northern Roebuck Bay (made between 1997 and
2000; Rogers et al. 2006b and D Rogers unpubl.) have indicated that disturbance
levels are high.
High disturbance levels to migratory shorebirds are of conservation concern.
Migratory shorebirds face tight schedules in the course of their annual cycle, and
have to live within tight energy budgets. Increase energy expenditure at roost sites
on the non-breeding grounds could prevent shorebirds from building up the
enormous fuel stores required for successful migration. Modelling of the energetic
costs of roosting in Roebuck Bay (Rogers et al. 2006b) has shown that disturbance
costs could become high enough to force shorebirds to abandon the north of
Roebuck Bay.
In view of the concern that shorebird disturbance lvels in Roebuck Bay may be
dangerously high, and increasing, Broome Bird Observatory initiated a disturbance
study in Roebuck Bay. The catalyst for the project was a grant of $10,000 from the
Western Australian Department of CALM, subsequently “topped up” by an additional
National Heritage Trust grant obtained through the shorebird conservation project of
WWFAustralia.
The study was carried out in 2005-2006, and the results are presented in this report.
We assess how much disturbance occurs on the northern beaches of Roebuck Bay,
4
Shorebird disturbance in Roebuck Bay 2005-2006
and how this level varies with time of year and site; we assess the causes of
disturbance, and we assess whether disturbance levels have increased in the last
few years. In addition we studied human beach-users on the northern beaches of
Roebuck Bay, in an attempt to find out how many people actually use the beaches,
and what their reasons for visiting are.
On the basis of these data, we put forward recommendations for future management
of the northern beaches of Roebuck Bay. We stress that these recommendations are
specifically focussed on disturbance at high tide roosts. In seeking feedback on this
project, we were frequently asked what the effects of the Broome Hovercraft were on
shorebird disturbance. This is a low tide issue, and we did not collect any information
about it in the course of this project.
5
Shorebird disturbance in Roebuck Bay 2005-2006
3.
Methods
3.1 Project organisation
The project was designed, and the data analysed, by Danny Rogers. An initial
workshop was jointly organised and conducted by Chris Hassell, Danny Rogers, Neil
McKenzie and Jan Lewis to introduce volunteers to the study and train them in data
collection techniques. Chris Hassell co-ordinated the fieldwork, assembling teams of
volunteers, ensuring data were collected in a consistent manner and entering data.
Chris Hassell and Neil McKenzie (cultural advisor) conducted a series of interviews
of beach users on each survey. Jan Lewis was involved throughout, especially in
preparation of the project and completion of the final report.
3.2 Data collection
Surveys were conducted twice every month from May 2005 to April 2006. Surveys
began two hours before the peak of high tide, and were concluded two hours after
the peak of high tide. In each month, one of these surveys was carried out on a
weekday, the other on a weekend. On a few surveys data could not be collected at
all sites because of a shortage of volunteers. Volunteer availability was most limited
in the wet season, when disturbance happened to be low anyway.
Surveys were carried out on five beaches (Fig. 1), selected because (1) These were
all known to be sites where shorebirds roost regularly, thus allowing adequate
samples to be built up; (2) they were considered representative of the range of
variability in disturbance levels that occur on the Northern Beaches. In this report we
have used the site names generally used by birdwatchers. Traditional names are
also given (in parentheses) below, but in some cases the names refer to broader
areas than the specific beaches that shorebird observations were focussed on.
From East to west, the sites where we collected data were:
1. Crab Creek Beach (Murragingun). A broad sandy beach, backed by low
vegetated dunes, 0-1 km west of the Crab Creek Mangroves; according to the
position of roosting shorebirds observations were made from sites known to
birdwatchers as “Sandy Blowout”, “Stilt Viewing” and “The Boiler”. During the
wet season this beach often holds more roosting shorebirds than any other
site on the northern shores of Roebuck Bay, but it varies and sometimes
holds no shorebirds at all, especially during the dry season. It is easilu
accessed from crab Creek Road, which runs only a few metres behind the
beaches, and is a popular fishing area, especially when threadfin salmon are
running during the dry season.
2. Wader Beach (Gurlbinwula). A reasonably narrow beach, rocky in places,
backed by 5-10m high red laterite cliffs. Once often used as a boat-launching
area, but vehicle access to the beach was closed by Broome Shire council (in
consultation with Broome Bird Observatory and the Rubibi) in the late 1990’s.
Crab Creek runs reasonably close to this beach, but human access to the
beach involves a short walk over broken ground. The beach is used fairly
consistently as a roost by moderate numbers of shorebirds (often in the low
6
Shorebird disturbance in Roebuck Bay 2005-2006
thousands), but tends to be avoided on higher tides when it becomes very
narrow.
3. Campsite Beach (Gurdidi Ngurnu). A moderately broad sandy beach, backed
by red laterite cliffs about 10 m high. It is a relatively secluded roost; Crab
Creek Road is some 50m behind the cliffs; there are some minor tracks
allowing vehicles to approach the cliff edge if they take a detour, but access
onto the beach is only possible for people on foot who are prepared to
scramble down the cliff. Numbers of shorebirds using this roost vary, but at
times (especially during the dry season) it can hold large numbers, up to
10,000 shorebirds. It tends to be avoided on higher tides when roosting
shorebirds are forced into narrow areas between the waterline and the cliffs.
4. Quarry Beach (Bingaja). A broad sandy beach, partly backed by low
vegetated dunes and partly backed by low red cliffs. The beach is often visited
by people, some associated with a house at the junction of the All-weather
Road with Crab Creek. It is a reasonably popular fishing area, and also
receives casual visitors, as the east end of the beach is the first point of
access to Roebuck Bay for people driving to the bay via the all-weather Road
to Crab Creek Road. Formerly used as a boat launching site, the traditional
point of vehicle access to this beach (at the eastern end) has now been
closed off. Nevertheless, some vehicles do still reach this beach, accessing
the beach from an access track about 2 km to the west and then driving
along shore to Quarry Beach itself. Vehicles using this route thus travel
through the western end of the beach, which would otherwise only be easily
access by people if they were prepared to walk a reasonably long way.
Quarry Beach is consistently used by roosting shorebirds, and is considered
of particular importance on higher tides, when it is one of the few northern
beaches that remains broad enough to be a suitable roost.
5. Simpson’s Beach (apparently no traditional name exists). This broad sandy
beach, backed by high sand dunes, lies between Broome Port and Town
Beach. Although this beach is in Broome, and reasonably close to all-weather
bitumen roads, the only ready access points to the beach are from the
southern end (at the commercial Hovercraft launching site) and from the north
(at Town Beach). A moderate number of visitors nevertheless walk along
Simpson’s Beach from these access points. The beach also has unusual
numbers of birds of prey in the dry season, when as many as 250 Black and
Whistling Kites have been seen there. In the wet season Simpson’s Beach
often holds good numbers of roosting shorebirds (counts of 3,000 shorebirds
are typical), but in the dry season shorebird counts there are very low.
7
Shorebird disturbance in Roebuck Bay 2005-2006
Campsite Beach
Simpson’s Beach
Crab Creek Beach
Quarry Beach
Wader Beach
Fig. 1. Roebuck Bay; the red lines depict the northern beaches of the bay, and sites
where disturbance observations were made are indicated.
Data were collected by volunteers (see Acknowledgements). Whenever possible we
positioned two volunteers at each site. Volunteer availability was low in the wet
season, but by this stage of the study most volunteers were experienced in the data
collection procedures, and a single observer at each site could collect adequate
data.
Observations were made from vantage points at which most or all of a shorebird
roosts could be scanned without causing disturbance to the shorebirds under
observation. It was not always easy to avoid causing disturbance, because
shorebirds sometimes moved during the course of the observation period, settling at
points closer to the observers than was desirable.
Two kinds of data sheet were filled in by all observers (Appendix 1). The core activity
was systematic recording of shorebird disturbance. Every 10 minutes observers
carried out a scan, recording the number of shorebirds present, and the percentage
of these birds in flight. These regular scans were used to calculate the amount of
time that shorebirds spent in disturbance flights at high tide. In addition observers
recorded any disturbances or flights noted at any time, allowing us to calculate the
number of alarm flights per hour. Not all flights were caused by disturbance (some
were natural movements caused by the tide). Flights were classified as alarm flights
if birds towered or gave alarm calls when they flew, or if there were other reasons to
8
Shorebird disturbance in Roebuck Bay 2005-2006
believe they had taken off due to disturbance. The perceived cause of alarm flights
was recorded whenever it could be identified.
Observers also recorded all people that they saw on their site during the observation
period. The number of people observed, their times of arrival and departure, and
their apparent activity were recorded. Brief descriptions of the people seen were
made to avoid double counting, and so we could tell whether or not these people had
been interviewed.
Beach users were interviewed whenever possible. Some interviews were carried out
by the observers recording disturbance, especially at Simpson’s Beach. Whenever
possible though, interviews were conducted by a mobile team consisting of Chris
Hassell and (when available), Neil McKenzie. This mobile team also dropped in
regularly on the volunteer observers to ensure that data were being collected in a
consistent manner between teams. The questionnaire used during the interviews
was designed to find out how often, and why, people visited the beaches of Roebuck
Bay; to find out how familiar they were with shorebirds and the problems posed by
disturbance; and to find effective methods of public education about shorebird
conservation. An equally important, though less formal objective of the interviews
was to educate beach-users about disturbance of shorebird roosts.
3.3 Data analysis
The data collected were used to construct two indices of disturbance levels. The
index most often used in this report was the number of alarm flights per hour. We
also calculated the amount of time spent in alarm flights by an individual per hour. In
doing this we restricted analysis to data collected in the regular scans made at tenminute intervals; it was assumed that this gave us a satisfactory representation of
the percentage of time that an individual spent airborne per high tide. The amount of
time spent in alarm flights is a fairly direct measure of the energetic costs of a roost.
However, there was potentially some error in this calculation, as it was based on
counts that had to be made quickly.
Both of the above indices tended to underestimate the amount of disturbance
caused, especially by people. Disturbance indices could only be calculated at sites
where shorebirds were present, so our dataset was skewed against sites that were
so heavily disturbed that they had been abandoned by shorebirds. This level of
disturbance may have been caused by birds of prey on some occasions (especially
at Simpson’s Beach) but was more likely to be caused by people. Birds of prey
tended to visit a site briefly, moving to another if few shorebirds were present.
People made longer visits, often remaining on the beach for hours; simply by being
there they prevented shorebirds from settling nearby.
Disturbance levels were influenced by a number of factors – day of the week, time of
year, numbers of shorebirds present at a roost, and tide height. In order to
unscramble these different effects we constructed a multivariate disturbance model
(Appendix 2) using linear regression. GLM models made using Systat 10 generated
identical results.
9
Shorebird disturbance in Roebuck Bay 2005-2006
4.
Results
We expressed the amount of disturbance as “number of alarm flights per hour” and
as “amount of time spent in flight”. The amount of disturbance observed in the
course of the study is presented in full in Appendix 2.
The amount of disturbance could potentially be influenced by several different
variables. We discuss these singly below. However, many of these variables interact
with one another, so a full assessment of their effects requires multivariate analysis.
The multivariate regression approach we used to do this is described in full in
Appendix 3. In short, the models we constructed predicted disturbance rates
reasonably effectively, and demonstrated that while some variables (especially time
of year) had a large effect on observed disturbance levels, others were of relatively
little importance.
4.1
Variables affecting disturbance levels.
Weekend/weekday: If people engaged in recreational activities contribute
substantially to disturbance of shorebirds on the beaches of Roebuck Bay, we would
expect disturbance levels to be higher on weekends. More people can get away from
work at these times, and our past experience is that even those without weekday
empolyment are more likely to visit the bay at weekends. Initial exploration of the
data collected in 2005/06 suggested that a weekend effect existed. Whenever
possible, disturbance levels at each site were measured twice every month, once on
a weekend and once a weekday. Disturbance levels (indicated by number of alarm
flights per hour) on weekends exceeded those on weekdays in 70.6 % of the 92
paired comparisons we could make within a site and within a particular month.
10
Shorebird disturbance in Roebuck Bay 2005-2006
Tide state: Previous analysis of Roebuck Bay data has shown disturbance levels
increase with tide height (Rogers et al. 2006b). On higher tides, shorebirds are
compressed into smaller areas on the northern beaches, and have to roost closer to
cover that may conceal predators. They may therefore become more wary, as they
will have more difficulty escaping if a predator attacks. Data collected in the present
study were consistent with this theory (Fig. 2). Our past experience has been that
disturbance levels on the beaches of Roebuck Bay are higher on rising tides than
they are on ebbing tides. Rather to our surprise, this trend was not strongly marked
in the data collected in the 2005-06 study (Fig. 2). Disturbance levels were higher on
rising tides in only 53.1% of the 81 paired comparisons possible where data were
available within a site for both ebbing and receding tides on the same day.
1.0
Alarm flight score
0.8
0.6
0.4
Tide type
0.2
0.0
3
4
5
6
7
8
Tide Height (m)
9
10
Ebbing
Peak
Rising
Figure 2. Number of alarm flights per site (corrected for the amount of observation carried out) plotted against
the height of tide at which alarm flights were made. Tide heights are clustered into 0.5 m intervals. Data points
outside the dashed line were based on short observation periods of two hours or less; data points inside the
dashed line were based on longer observation periods of 3.5 to 33 hours.
Bird numbers present: Large shorebird flocks tend to be more readily disturbed than
shorebirds occurring singly or in small groups (pers. obs.). This is very probably
11
Shorebird disturbance in Roebuck Bay 2005-2006
because if a shorebird takes off in alarm, adjacent flockmates will take off as well,
even if they have not seen the potential source of danger. Large flocks tend to be
more vigilant than small flocks because there are more birds present looking out for
potential sources of danger. Figure 3 indicates that this effect occurred during our
study. The relationship between flock size did not appear to be linear; rather,
disturbance levels climbed abruptly if birds numbers exceeded 50-100. For this
reason, it was most convenient to analyse the effect of bird numbers present on
disturbance levels by converting the bird numbers present to a logarithmic scale (Fig.
3).
25
Alarm flights per hour
20
15
10
5
0
-5
1
10
100
1000
10000
100000
Average number of birds present per high tide
Figure 3. Alarm flights per hour (corrected for the effects of constant, month and tide height identified by
multiple regression), plotted against the average number of shorebirds present at a site through a high tide
observation period. Note that the scale on the X axis is logarithmic.
12
Shorebird disturbance in Roebuck Bay 2005-2006
Site: The sites at which shorebird disturbance levels were measured in this study
were not identical. Some beaches were broader than others; some were backed by
low cliffs and pindan vegetation (offering potential cover for predators) while others
were backed by sparsely vegetated sand-dunes offering little cover for predators;
some were easily accessed and often visited by people, while others were less
accessible and less regularly visited. Plots of disturbance levels at the different sites
suggested differences were rather small (Fig. 4). However, this picture might be
biassed if shorebirds completely abandon particular beaches in the face of high
disturbance, as we could only measure disturbance levels if birds were present at
the site being investigated.
Alarm flights per hour
5
4
3
2
1
0
CS
QB
SB
Site
SV
WB
Figure 4. Alarm flights per hour (± standard error), plotted by site. CS = Campsite Beach, QB = Quarry Beach,
SB = Simpson’s Beach (between Town Beach and Broome Port), SV = Stilt Viewing (the layby from which
roosting flocks just west of Crab Creek were usually observed) and WB = Wader Beach.
13
Shorebird disturbance in Roebuck Bay 2005-2006
Month: There were substantial differences in disturbance levels in different months.
These differences were clear both on unmodified data, and when adjustments were
made to correct for potentially confounding interactions with other variables (Fig. 5).
Disturbance levels were high from May to July, and rose to a high peak in August.
We had expected this to be the case, as there are influxes of both birds of prey and
tourists to Roebuck Bay during the dry season. In August adult shorebirds begin
returning to Roebuck Bay from their northern breeding grounds, and the increase in
the number of birds present might also influence disturbance levels.
6
4
Coefficient
2
0
-2
-4
-6
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Figure 5. Regression co-efficient for number of Alarm flights per hour (with disturbance at January set at 0),
adjusted for effects of tide height and number of birds present, ± 95% confidence limits, plotted by month.
14
Shorebird disturbance in Roebuck Bay 2005-2006
4.2
Causes of disturbance
Overall, 918 alarm flights were observed at roosts in the course of the study. Flights
were classified as “alarm flights” if birds gave alarm calls and towered, or if there
were other reasons to believe they took off because they had been frightened by
something. The total does not include a further 446 flights which were thought to be
“commuting” flights made between pre-roosts and roosts, or which observers were
unable to classify.
The causes of alarm flights are summarised in Table 1. It was not possible to identify
the cause of 365 (39.8%) of the 918 alarm flights observed, and these are not
included in Table 1.
Table 1. Causes of alarm flights from the Northern Beaches of Roebuck Bay
Number of alarm
flights
% of alarm flights of
identified cause
Birds
prey
311
55.3%
of
False Alarm
Observers
Aircraft
82
31
24
Other
people
114
14.6%
5.5%
4.3%
20.3%
Birds of prey were the main cause of disturbance. In 79 cases the raptor species
causing disturbance was identified: most flights were caused by White-bellied SeaEagles (30.4%), Brahminy Kites (25.3%), Black Kites (15.2%) and Whistling Kites
(15.2%). Small numbers of disturbances were also caused by Brown Goshawks,
Collared Sparrowhawks, Swamp Harriers, Australasian Hobby, Brown Falcon,
Lesser Frigatebird (not strictly speaking a bird of prey, but sometimes attacks gulls
and terns in shorebird roosts) and Osprey (possibly false alarms, as we have never
seen Osprey hunting shorebirds).
Many of the alarm flights (14.8%) observed were false alarms. Most commonly these
were caused by the sudden appearance of flying birds that were presumably
mistaken for predators, though they were in fact species that were not a real source
of danger. These included Silver Gulls, several species of tern and heron, Whimbrel,
Pied Oystercatcher, and once, a Rainbow Bee-eater. Other unusual causes of
disturbance observed included splashing waves, a passing Willy-Willy and windblown litter. The high number of false alarms is indicative of the wariness of the
shorebirds of Roebuck Bay while roosting.
Remaining disturbances were caused by people. A small proportion were caused by
the observers recording disturbance (often because shorebirds settled or walked
close to the observers and then suddenly noticed their presence). Some
disturbances were caused by aircraft. Helicopters flew over the study site four times
during the observation period, twice causing substantial disturbance (our previous
field experience at of helicopters at Roebuck Bay is that shorebirds are almost
always alarmed if helicopters pass by). Nineteen disturbances were caused by low-
15
Shorebird disturbance in Roebuck Bay 2005-2006
flying airplanes (usually approaching or taking off from Broome International Airport),
but on least 80 occasions shorebirds did not react when airplanes flew low overhead.
About 20% of observed disturbances were caused by people. This is likely to be an
underestimate of the amount of disturbance caused by people, as disturbance
observations could only be made if shorebirds were present and they tended to
avoid roosts if people were already on the beaches. In 66 cases the activities of the
people who disturbed shorebirds were identified. Of these, 30.2% of disturbances
were caused by vehicles (either on the beaches, or making loud sudden noises on
sections of Crab Creek road that are very close to shorebird roosts). 18.2% of
disturbances were caused by birdwatchers, 10.6% by people known to be fishing,
and 9.1% by people walking dogs. The remaining 30.3% of disturbances were
caused by people walking on the beaches, but not obviously fishing or birdwatching.
Sites did not differ greatly in the overall amount of disturbance that they received.
However, there appeared to be differences in the causes of disturbance at different
sites (Fig. 6). Birds of prey caused most disturbance at Wader Beach and Campsite
Beach; both these roosts are backed by low cliffs which can be used as cover by
hunting raptors, and it is possible that forces birds here to be more wary of raptors
than they are in sights where raptor approaches can be seen from long distance.
The apparently low levels of raptor disturbance at Simpson’s Beach may be an
artefact of data collection, as our field impression is that birds of prey (especially
Black and Whistling Kites) are more common at this site than at any of the other
roosts considered in this study. In the dry season as many as 250 kites were
sometimes seen at this site. However very few shorebirds roosted at Simpson’s
Beach in the dry season, resulting in us calculating low levels of raptor disturbance
for the site when in fact, the high numbers of kites present may have actually been
the cause of the apparently low shorebird numbers.
People caused most disturbance at the two most westerly of the roosts considered,
Quarry Beach and Town Beach. These sites are relatively close to Broome and
easily accessed by beach-walkers. Disturbance caused by aircraft increased on an
east-west gradient along the northern shores of Roebuck Bay. This shoreline is a
regularly used flight path for aircraft taking off and (especially) landing at Broome
International Airport, and aircraft using this flight path are at lower altitude near
Broome (e.g. at Quarry Beach) than at the eastern end of the shoreline (Crab
Creek).
16
Shorebird disturbance in Roebuck Bay 2005-2006
Figure 6. Number of alarm flights caused by different sources of disturbance, by site.
250
Number of alarm flights
200
Tide
People
150
Observer
False alarm
100
Birds of prey
Aircraft
50
0
Crab Ck
Beaches
Wader Beach
Campsite
Beach
Quarry Beach
Simpson's
Beach
Site
Shorebird disturbance levels fluctuated greatly by month. The relative disturbance
contributions of birds of prey, people, false alarms and aircraft did not vary by month
in a very predictable manner, but all of these variables tended to be highest in the
winter months or in early spring (Fig. 7).
Fig. 7. Number of alarm flights caused by different causes of disturbance, by month
200
180
Number of alarm flights
160
140
People
120
Observer
100
False alarm
Birds of prey
80
Aircraft
60
40
20
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Month
17
Shorebird disturbance in Roebuck Bay 2005-2006
4.3
Human use of the northern Beaches of Roebuck Bay
People using the beaches of Roebuck Bay were counted by the volunteer teams at
their sites in the course of every disturbance-recording session. These totals are not
a complete count of the number of people using the northern bay, as other people
may have been present on other beaches. People present on other beaches were
recorded when observed by the mobile team (Chris Hassell and Nial McKenzie).
While these counts were not complete, it is considered that a large proportion of the
people using the Northern Beaches were recorded, and also that search effort was
reasonably consistent between months.
The number of people observed on the beaches is presented in Table 2. There was
a strong seasonal influence, with largest numbers occurring on the beaches during
the dry season. This effect was especially marked on the beaches along the northern
shoreline of Roebuck Bay, where almost nobody was seen between December and
February; this was probably in large part because of the condition of Crab Creek
Road, which is officially closed at this time of year and was deeply flooded in parts.
Within months, more people used the beaches on weekends than on weekdays.
Table 2. Number of people observed on the Northern Beaches of Roebuck Bay in the course of the disturbance
study.
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Northern Beaches
Weekend
Weekday
0
0
0
3
43
1
18
3
52
13
39
10
80
17
35
13
31
21
13
22
10
1
0
1
Simpson’s Beach
Weekend
Weekday
11
17
30
3
4
27
37
13
6
8
3
0
4
2
All roosts
Weekend
11
17
43
21
56
66
117
48
37
13
18
Weekday
33
1
3
13
13
17
17
23
22
1
1
18
Shorebird disturbance in Roebuck Bay 2005-2006
Activities of people occurring on the beaches could often be assessed by simply
looking at them in the course of data-recording sessions. A summary of the activities
identified is given in Table 3. Usually people occurred in groups, with the largest
groups involving parties that were fishing, boat launching or engaged in general
recreation; birdwatchers and walkers were more solitary. Most (60.6%) of the beachvisitors observed were fishing, with rods, throw-nets or spear. People walking along
the beach, and bird-watchers, were also present in reasonable numbers. There were
smaller numbers involved in stationary recreation (e.g. sight-seeing, picnicking or
swimming; when a group of people was involved in both stationary recreation and
fishing, we classified them as fishing), carrying out post-graduate bird research, or
launching boats from Sabu Rocks or Crab Creek at high tide.
The number of people counted on different beaches of Roebuck Bay during the
study, and their activities, are summarised in Table 3. Although counts of people at
“other sites” are not comprehensive, it is considered that a large proportion of the
people using the beaches of Roebuck Bay on the study days were counted. Almost
half of the beach-users observed were found on the beaches immediately west of
Crab Creek, a popular fishing area. Simpson’s Beach was also heavily used, as was
Quarry Beach, a site where walkers were disproportionately common.
Table 3. Number of people observed at different sites on the northern beaches of Roebuck Bay in the course of
disturbance fieldwork.
Activity
Birding
Boat launch
Fishing
Recreation
Research
Unknown
Walking
Total
Crab
Creek
Beach
28
29
190
26
1
12
15
301
Campsite
Beach
Quarry
Beach
Simpson's
Beach
15
17
13
6
3
33
5
2
154
8
6
4
55
23
70
33
197
Wader
Beach
Other
sites
Total
24
5
9
27
7
0
0
0
48
78
43
429
63
4
18
77
712
8
4
3
2
41
19
Shorebird disturbance in Roebuck Bay 2005-2006
Volunteers classified the amount of disturbance that each category of human activity
caused to shorebirds on a three-point scale (Table 4). It was often impossible to
make an assessment of the amount of disturbance caused, usually because there
were no shorebirds present anywhere near the beach-users observed. The data
collected indicated that the most intrusive activity undertaken on the beaches was
simply walking along them. Most people fishing, and most people birdwatching
caused no disturbance, but some caused a little disturbance and some caused a lot.
Although the relative proportions of disturbance caused by fishing and birdwatching
were similar, the reasons behind this were probably quite different. People who were
fishing did not often cause substantial disturbance as they were usually based in a
single place. Birdwatchers travelled more widely but usually made an effort not to
disturb birds.
Table 4 – Activities of beach-users on the Northern Beaches, and the amount of shorebird disturbance caused by
each activity.
Activity
Birding
Boat launching
Fishing
Recreation
Research
Unknown
Walking
Grand Total
Number of
beach-users
(average
group size)
78 (2.7)
43 (3.3)
436 (3.4)
63 (3.5)
4 (1.3)
18 (2.6)
77 (1.7)
719 (3.1)
As % of
total beachusers
Nunber of groups
for
which
bird
disturbance assessed.
Amount of bird
caused
None
Little
10.8%
6.0%
60.6%
8.8%
0.6%
2.5%
10.7%
100.0%
24
0
67
10
3
5
34
143
70.8%
12.5%
16.7%
70.1%
80.0%
100.0%
80.0%
44.1%
65.7%
11.9%
20.0%
0.0%
0.0%
8.8%
11.2%
17.9%
0.0%
0.0%
20.0%
47.1%
23.1%
disturbance
Lots
Beach users were interviewed whenever practical to find more about who visits the
beach, why they do so, and how well informed they are about the shorebirds of
Roebuck Bay. The great majority of the interviews were conducted by DHJ and NM,
who did not visit Simpson’s Beach in the course of their mobile surveys (the site was
too distant from the remaining roosts); beyond this bias, we consider the sample to
be representative of the people present on the beaches. A questionnaire was used
to ensure systematic data collection (Appendix 1). Fifty-five interviews were
conducted. Usually people were in groups, and when this was the case, only one
person from the group was interviewed; overall there were 159 people in the groups
sampled (average group size 2.89, standard deviation 1.931). Nobody was
interviewed more than once.
All interviews conducted were cordial, and they usually resulted in lengthy
conversations about shorebirds and Roebuck Bay. We suspect that interactions of
this kind may be a more effective way of informing the public about disturbance
problems in Roebuck Bay than more conventional methods such as signposting or
brochures. As many of the beach-users on the northern shores turned out to be
people who visit the beaches regularly (especially local residents), it is feasible for an
interviewing team to make direct contact with a fairly large proportion of the beach
users at Roebuck Bay in only a few days.
20
Shorebird disturbance in Roebuck Bay 2005-2006
Only two of the people interviewed had reached the beaches of Roebuck Bay
without a vehicle (a beachcomber at Simpson’s Beach who had walked to the site
from his accommodation in Broome, and a bird-watcher staying at Broome Bird
Observatory). Fifty of those interviewed had driven to the bay, the great majority
(84%) using four-wheel drive vehicles. Some had arrived by two-wheel drive vehicles
(10%), in a chartered bus (4%) or on a hired scooter (2%). Human visitation to the
bay thus appears to be restricted by road conditions.
The origins of people interviewed are summarised in Table 5. Over half of the
interviewees came from the Broome area or were visiting from elsewhere in the
Kimberley, and individuals from these region visited the Northern Beaches far more
times a year than did visitors from further away. Over half of the Broome residents
and Kimberley visitors interviewed identified themselves as Aboriginal or Torres
Strait Islander, an indication of the cultural importance of Roebuck Bay to Aboriginal
people. The majority of visitors from further away lived in south-western Australia or
interstate; in addition to being more numerous than visitors from overseas, Australian
visitors stayed in the Broome area for longer and made more frequent visits to
Roebuck Bay.
Table 5. Origins of visitors to Roebuck Bay.
Origin
of
beach user
Broome
Kimberley
SWA
Interstate
Overseas
Groups
People
22
1
10
20
2
73
9
21
53
3
Length of stay in
Broome (days)
180
54.3
32.2
14
Average visits to
Roebuck Bay pa
91
72
5.8
26
2.5
Aboriginal
Groups
People
11
1
1
1
0
41
9
2
6
0
The reasons interviewees gave for their visits to Roebuck Bay are summarised in
Table 6. Often they had more than one reason for visiting (e.g. cultural and fishing
visits were often interlinked) but we only present the main reason here. Recreational
bird-watching and bird research are combined below, and the site-seeing category is
rather broad, including beach-combing and walking. All visitors from Broome and the
Kimberley region who were interviewed were fishing or involved in cultural activities
(there was something of a bias against Broome-based birdwatchers in this survey,
as the volunteers conducting the survey were not interviewed, and they comprised a
fair proportion of the Broome bird-watching community). Visitors from further away
included people fishing and site-seeing, but bird-watchers predominated.
Table 6. Activities of visitors to Roebuck Bay
Cultural
Fishing
Birding
Site-seeing
21
Shorebird disturbance in Roebuck Bay 2005-2006
Origin
of
beach user
Broome
Kimberley
SWA
Interstate
Overseas
Total
Groups
People
Groups
People
4
1
16
9
17
56
5
7
9
17
29
83
5
25
Groups
People
Groups
People
2
10
2
14
4
28
3
35
3
3
8
8
6
16
The questionnaire included some questions intended to provide guidance on how
much visitors know about the shorebirds of Roebuck Bay. On the whole visitors were
not very well informed. Most bird-watchers, a few anglers and one tourist were aware
that the shorebirds nest in the northern hemisphere, but most interviewees got the
question wrong (Table 7). We also asked interviewees “Why do you think shorebirds
use these beaches?” Only two bird-watchers and five anglers correctly answered
that the beaches were used as a roost. Some of the many incorrect answers
received might have resulted from misinterpretation of the question (most people
interviewed thought the beaches played some role in feeding or migration), but in
general it was clear that the public, and even visiting birdwatchers, did not have a
good understanding of the importance of the beaches to shorebirds.
Table 7. Interviewee answers to the question “Where do you think these shorebirds nest?” R = right answer, W
= wrong answer.
Origin
of
interviewee
Activity
Birding
Cultural
Fishing
Site seeing
Broome
R
2
1
W
1
4
13
3
Kimberley
SWA
R
W
R
1
1
1
4
Interstate
Overseas
W
R
6
R
1
1
3
2
W
W
1
To get an idea of how to provide information to beach users in Roebuck Bay, we
asked interviewees were asked how they first found out about the bay (Table 8).
Most visitors had first heard about the site by word of mouth, usually from friends or
family; a number of bird-watchers had become aware of the site through birding
magazines or other literature. Interestingly, considering the amount of fishing that
goes on in Roebuck Bay, nobody interviewed had first found the bay as a result of
fishing magazines or other literature. Forty-two of 53 interviewees had never noticed
signs or other information about disturbance of shorebirds of Roebuck Bay. The
remaining 9 had heard something about the problem though a visit to Broome Bird
Observatory (n = 3), a book (n=1), brochures (n=2), the bird platform outside BBO
(n=1), a signpost at Quarry Beach (n=1), or television or radio (n=2).
Table 8. Number of people that first found out about Roebuck Bay through different sources of
information (separate columns for people from different regions).
Information source
Word of mouth
Birding
Broome
16
Kimberley
1
SWA
6
Interstate
9
8
Overseas
22
Shorebird disturbance in Roebuck Bay 2005-2006
Angling
Unknown
Broome Tourist office
Other tourist literature
Internet
Self-exploration
2
2
1
1
1
1
1
4
1
23
Shorebird disturbance in Roebuck Bay 2005-2006
4.4
Costs of disturbance, and are levels increasing?
Although the relationship was not very neat, the amount of time that birds spent in
flight at high tide was significantly correlated with the number of alarm flights per
hour (r2 = 0.065, df = 94, P = 0.012). The average amount of disturbance with sites
and months pooled was 14.3 minutes per high tide, but this value varied
considerably (standard deviation 19.381, range 0 -111.5, n =95). Multivariate
regressions (not presented in full here) indicated that the amount of time spent
airborme varied significantly by month (figure 8). The highest levels of disturbance
were seen in June and August, the lowest levels in March. Much variation occurred,
especially if different sites were examined separately; the amount of time spent in
flight could be strongly influenced by unpredictable events such as the presence of a
persistent hunting bird of prey. It could also have been influenced by observer error,
as recording this variable required observers to make rapid counts of both the
numbers of birds present, and the number of these birds in flight. The amount of time
spent in flight is not as easily or repeatably recorded as the number of alarm flights
per hour. It is however a more direct measure of the energetic costs of disturbance.
Fig. 8. Amount of time spent in flight per high tide per month ± s.e.
Time in flight (mins per high tide)
55
39
23
7
-9
1 2 3 4 5 6 7 8 9 10 11 12
Month
24
Shorebird disturbance in Roebuck Bay 2005-2006
Statistical models have been developed that allow calculation of the energetic costs
of flight (Nudds and Bryant 2000; Kvist et al. 2001), provided the amount of time
spent in flight is known. Flight is a costly activity for birds. For example, 2.77 KJ of
energy (about the amount of energy that can be obtained from consuming a large
bivalve) is sufficient for a lean Great Knot to sleep for 6 hours; or to forage for 159
minutes; or to fly at a steady pace for 26 minutes. Alarm flights involve take-off,
climbing and flight velocities that are uneconomical, making them considerably more
expensive than steady flight; the energy obtained from the hypothetical large bivalve
above would only fuel 7.5 minutes of short-range flight.
The flight costs of roosting shorebirds from the northern Beaches of Roebuck Bay
have been explored by Rogers et al. (2006). It was calculated that if Great Knots on
the northern beaches need to fly for 15 minutes or more per high tide as a result of
disturbance, on tides of intermediate height (6-8.2 m), they would consume more
energy than would be required to fly to Bush Point. Bush Point (at the southern end
of Roebuck Bay) is the only alternative roost site available in such tide conditions.
It would appear from figure 8 that disturbance levels at Roebuck Bay do indeed rise
so high that shorebirds are forced to fly for 15 minutes or more per high tide,
especially during the winter months. Furthermore, it is possible that this influences
shorebird numbers on the northern shores of Roebuck Bay during the austral winter.
Table 9 compares shorebird counts from three major north-western Australian sites
in the austral summer of 2004 and the following austral winter (July 2005). A 50 km
stretch of Eighty-mile Beach was counted on both surveys, and the proportion of
birds remaining at this pristine and undisturbed site in the austral winter was about
15% that of birds observed in the preceding austral summer. The winter-summer
ratio recorded in northern Roebuck Bay was lower. In contrast, the winter-summer
ratio recorded at Bush Point was considerably higher, a trend that has been noticed
on several other counts in the region in recent years (C. J. Hassell, D.I. Rogers,
pers. obs.). It is possible that the costs of disturbance on the northern shores of
Roebuck Bay are so high in the winter months that many shorebirds relocate to Bush
Point during the austral winter. This idea has not yet been proved, but it is the most
plausible explanation for the discrepancy between Bush Point and Roebuck Bay
count ratios that we have been able to find.
Table 9. Comparison of winter counts and summer counts at Eighty-mile Beach, Bush Point and on the northern
shores of Roebuck Bay.
Site
Eighty-mile Beach
Bush Point
N. Roebuck Bay
Nov. 2004
276765
55677
41364
July 2005
41797
38552
4261
% of birds remaining
15.1%
69.2%
10.3%
The human population of Broome is growing, and this could lead to increases in the
amount of shorebird disturbance on the Northern Beaches of Roebuck Bay. Some
data on disturbance levels in Roebuck Bay were collected by DR in the course of
roost choice studies between October 1997 and February 2000. The regression
models developed from the 2005-06 data in this report allow us to predict how much
disturbance would have happened in the previous survey period for particular
25
Shorebird disturbance in Roebuck Bay 2005-2006
heights of tide, according to the number of birds present. Figure 9 compares these
predictions with the amount of disturbance actually observed in the 1997-2000 study
period. In general the correspondence is reasonably good, suggesting that there
have not been large changes in disturbance levels over the past decade. There may
have been a subtle increase through, given that the amount of disturbance predicted
by the 2005/06 models exceeded that observed on 11 of the 15 surveys conducted
between 1997 and 2000.
Alarm flights per hour
12
10
8
6
4
2
0
v ct ct
b
g
g ct ct ct ct
g
g ct
g ct
Fe Au No O O Au Au O O O O Au O Au O
10 20 C 3 C 5 C 7 21 22 B 26 B 8 B 9 B 15 19 B 20 25 B 4
B
B W
C C CS CS Q
Q Q W
CC CC C
W W W
2005/06 model
1997-2000 data
Site and date
Fig. 9. Alarm flights per hour observed at Crab Creek (CC), Campsite (CS), Quarry Beach (QB) and Wader
Beach (WB) between October 1997 and February 2000, compared with the number of alarm flights predicted at
these sites (given tide conditions and number of birds present) by regression models calibrated on 2005-06 data.
If disturbance levels on the northern shores of Roebuck Bay are increasing and
forcing some birds to move to Bush Point during the dry, we would expect to see a
decline in the number of shorebirds using the northern beaches during the annual
“winter count”. This count has been carried out in repeatable fashion along the
northern beaches of Roebuck Bay since 1993. A plot of data from these counts (Fig.
10) suggests that winter counts in the bay have indeed been declining, though the
data series is not long enough to assess whether this trend is statistically significant.
There are some other data suggesting a decline in shorebird populations during the
dry season along the northern shores of Roebuck Bay. In two of the past three years
shorebirds from the northern Roebuck Bay have roosted on salt scolds on Roebuck
Plains (in preference to the Northern Beaches) when these areas were damp,
despite the fact that this required a substantial increase in the distance they
commuted at high tide. Although these birds returned to the northern beaches after
the salt scolds had dried out, we believe the change in roosting habitat indicates that
shorebirds try to avoid the high disturbance levels found on the northern beaches
during the austral winter. Finally, surveys of shorebird densities on the northern
mudflats of Roebuck Bay carried out in the dry season (in 1998, 2003 and 2006)
revealed proportionately low densities were present in the Dampier Creek area
relative to densities of shorebirds in the east of Roebuck Bay. In wet season surveys
26
Shorebird disturbance in Roebuck Bay 2005-2006
carried out in the same way (in 1997, 1998 and 2000), shorebird densities in the
Dampier Creek area were proportionately much higher (D. Rogers unpubl. data).
This difference is unlikely to have been caused by foraging considerations, as
benthos sampling indicated that there was ample food available on the flats. It may
be that these areas had become relatively unsuitable for shorebirds because the
nearest roost sites, Quarry Beach and Town Beach, both happen to be heavily
disturbed areas.
Dry season shorebird total
12000
8000
4000
0
1990
1995
2000
Year
2005
2010
Fig. 10. Dry season counts (June-July) from the northern shores of Roebuck Bay. Data from the 1998 count
were excluded as it was carried out in August, after adult shorebirds had begun to return from the breeding
grounds. The trend line has a negative gradient, but the relationship between year and counts was not
statistically significant (r2 = 0.16, n=13, P = 0.175).
27
Shorebird disturbance in Roebuck Bay 2005-2006
5.
Discussion
This study has confirmed that shorebirds roosting on the northern beaches of
Roebuck Bay experience high levels of disturbance. In the winter months
disturbance causes increases in energy expenditure that could make birds abandon
these roosts. The nearest alternative roost in dry conditions, on tides of intermediate
height, is at Bush Point, c. 25 km away. Radio-telemetry (Rogers et al. 2006a) and
physiological modelling (Rogers et al. 2006b) indicate that the energetic costs of
roosting at Bush Point, and commuting to feed on the rich intertidal mudflats in the
north of Roebuck Bay, are too high to be sustained. Accordingly a loss of the
roosting areas on the northern beaches would also effectively result in a loss of
feeding areas to many shorebirds, and would in the long run lead to population
decline (Rogers et al. 2006b), as well as the loss of a spectacle (shorebirds roosting
on the northern beaches) that attracts many visitors to Broome.
The good news is that shorebird disturbance levels in Roebuck Bay only reach
disturbingly high levels for part of the year, and this time of year happens to coincide
with the period in which numbers of migratory shorebirds are naturally low. Roebuck
Bay is used as a non-breeding area by migratory shorebirds. Adult migratory
shorebird species are usually found in the northern hemisphere during the winter
months from May to August, as they migrate to breeding grounds from the Chinese
and Mongolian steppes to the high arctic. Most return to northern Australia between
August and November.
In most species of coastal shorebird in Roebuck Bay, immatures do not migrate
north, instead remaining on the Australian non-breeding grounds until they are two,
three or four years old (this age varies according to species). Accordingly, for most of
the austral winter, only immature migratory shorebirds remain in Australia. As
Australian shorebird populations are low at this time (usually 10% to 20% of those
found in the Australian summer), there is probably little competition for food on the
mudflats, allowing shorebirds to shift to less intensively disturbed feeding and
roosting areas. Count data collected in Roebuck Bay over the last decade or so
suggest that this may be happening, as the number of shorebirds found on the
northern beaches has been declining since 1992. The relatively high numbers of
shorebirds found at Bush Point during the winter months may also indicate that some
shorebirds are being forced from the Northern Beaches of Roebuck Bay by heavy
disturbance.
There are brief periods of overlap between the period of high disturbance rates and
the presence of adults. In most species this is likely to happen in August and
perhaps early September. High disturbance levels in May may also influence a few
late-migrating species such as Red Knot.
Most roost disturbance in Roebuck Bay was caused by birds of prey and by people.
Disturbance by birds of prey is natural, and the northern shores of Roebuck Bay
would be experience high disturbance levels even if the site was completely pristine.
Numbers of birds of prey in Roebuck Bay have never been counted systematically,
though on the basis of general birdwatching experience we have little doubt that
there is an influx of raptors (especially Black Kites and Whistling Kites) to the
coastline of Roebuck Bay during the winter months. In the absence of quantitative
28
Shorebird disturbance in Roebuck Bay 2005-2006
data it is difficult to tell whether raptor numbers in the area have been changing. We
suspect that numbers of Black and Whistling Kites may have increased, and this
would not be unexpected, both being species that often feed on carrion around
human settlements, garbage tips and roads.
People also caused a good deal of disturbance on the shores of Roebuck Bay, and
were responsible for 20-30% of the alarm flights observed. Our survey methods
might have resulted in an underestimate of the costs of human disturbance, because
we could only collect data if shorebirds were present, yet the presence of humans on
a beach could discourage shorebirds from settling there, and make them join other
shorebird flocks. Roost disturbance levels increased with flock size, so compressing
shorebirds into small roosting areas will increase disturbance levels.
People from many places were attracted to the beaches of Roebuck Bay, and they
used them in a variety of ways. People who live in the Broome area were the most
common visitors to the beaches, and the most common activity was fishing. Birdwatching (especially by visitors from interstate or overseas) was also a common
activity, and a reasonable number of tourists dropped in on the bay for general sight
seeing or beach-walking. However, the number of tourists visiting the beaches was
probably lower than might have been expected given the proportion of tourists to
residents present in Broome during the dry season. Access to the bay may have
been an important part of this phenomenon. The majority of visitors to the bay
reached the area in four-wheel drive vehicles, and many tourists flying into Broome
probably do not have access to such vehicles.
The activity seen causing most disturbance to shorebirds on their roosts was simple
beach-walking. Fishing and bird-watching caused proportionately less disturbance;
anglers did not usually cause disturbance as they were usually fairly sedentary, and
bird-watchers did not intentionally cause disturbance as this would have prevented
them seeing birds well. In this study some shorebird disturbance was caused by the
volunteers recording the data, although they were taking pains not to frighten birds.
We suspect that the presence of people on the beach will inevitably cause some
shorebird disturbance, no matter how non-intrusive their behaviour is.
Most beach-users did not know a great deal about the role that the northern beaches
of Roebuck Bay plays in the economy of shorebirds, and were thus unaware of why
disturbance could be harmful. All interviews conducted were cordial. Our general
impression was that most visitors to the northern beaches were well intentioned, and
would try to avoid causing disturbance if they knew more about the problem.
29
Shorebird disturbance in Roebuck Bay 2005-2006
6. Conclusions and recommendations
We consider disturbance levels of shorebirds on the northern beaches of Roebuck
Bay to be too high. At present we regard the situation as worrying rather than critical,
because disturbance levels happen to be highest at a time when shorebird numbers
in the bay are naturally low. We therefore do not advocate drastic measures such as
road closure to control levels of shorebird disturbance; such actions could cause
community resentment that would in the long run be detrimental to the shorebirds of
Roebuck Bay. However, we do recommend:
1. No further development along Crab Creek Road, as this will inevitably
increase the number of people visiting the northern beaches.
2. In conjunction with Yawuru traditional owners, identify and implement
measures to ensure that there is no vehicle access onto the beaches apart
from the boat launching ramp beside Sabu Rocks, and at Crab Creek.
Signposting or a barrier required to ensure that vehicles at the boat launching
area at Crab Creek do not drive westwards onto traditional shorebird roosts.
3. No creation of additional access points onto Simpson’s Beach. Development
on or beside the shore between Broome Port and Dampier Creek should be
only be permitted if their potential effects on disturbance of shorebird roosts
have been assessed and found to be negligible.
4. Initiating discussions with Broome International Airport and other relevant
authorities to: (a) prevent helicopters flying near the shoreline, especially to
the west of Dampier Creek; (b) investigate whether flight paths of commercial
aircraft approaching Broome International Airport can be slightly realigned so
they do not pass so close to shorebird roosts on the northern shores of
Roebuck Bay, especially at Quarry Beach.
5. Allocation of funding to enable the continued careful monitoring of disturbance
levels. This could be done with the methodology used in this study. Annual
surveys would be desirable, but surveys every two years would be adequate.
Surveying need only be done from April or May to September, as disturbance
levels are low from October to March.
6. Initiating a monitoring program for birds of prey in the Broome area to
establish seasonal patterns in abundance, and to establish a baseline so we
can tell if numbers are increasing. It may be possible to tie this in with other
survey work (e.g. Silver Gulls, direct counts of people on the beaches).
7. Further public education: (a) A signposting project has been in progress for
some time, and should be completed. This study suggests strategic sites for
signage about disturbance include Crab Creek, both the northern and
southern ends of Simpson’s Beach, and the access roads to Quarry Beach
and Wader Beach. (b) Continue the program of interviewing beach-users. (c)
Brochures about shorebird disturbance to be distributed from Broome Bird
Observatory, the Broome Visitors Centre and other outlets in Broome. A
suitable brochure, prepared by Rubibi as part of the Shorebird Conservation
Project, already exists. (d) Local publicity about the disturbance problem
every August, targeting Broome residents through (e.g.) radio interviews, local
newspaper (including the fishing page) articles and possibly Goolari. In
conjuction with KLC and the Yawuru traditional owners, develop an education
strategy aimed at Aboriginal people.
30
Shorebird disturbance in Roebuck Bay 2005-2006
If these publicity measures do not result in detectable decrease in the amount of
disturbance within three years, or if winter counts of shorebirds continue to decline,
more intrusive measures to control shorebird disturbance may be needed.
Possibilities include:
1. Engineering works to restrict human access to key wader roosts. This may be
of particular importance at Quarry Beach, often visited by beach-walkers.
2. Re-routing of Crab Creek road, or parts of it, so that vehicles do not pass so
close to roosts easily disturbed from the road (e.g. Tattler Rocks, Wader
Beach, some of Crab Creek Beach). Such measures should not be
undertaken unless steps have been taken to minmise disturbance that might
result from increased human visitation.
3. Imposing dog restrictions (e.g. designating selected beaches as dogs-onleads sites or as dog-free).
7.
Acknowledgements
This study was funded jointly by the Western Australian Department of Conservation
and Land Management (CALM) and through National Heritage Trust funding
obtained through the Shorebird Conservation Project of WWF-Australia. Thanks to
both funding bodies for allowing variations to the project timelines to enable the
project to proceed. Important early support for the project (which helped secure
funding) was provided by the Roebuck Bay Working Group.
The study was carried out by Broome Bird Observatory, who also provided a base
for the fieldwork and introductory workshop; the wardens and their teams (Ricki
Coughlan, Chris Sanderson and Belinda Forbes; then Pete Collins and Holly Sitters)
were helpful throughout the study. Neil McKenzie, representing Rubibi, was a very
important part of this project. The assistance of the Rubibi, traditional owners group
and Kimberley Land Council both in supporting the project concept, its establishment
and in ensuring that the interviews went smoothly, is greatly appreciated.
Finally, the volunteers who collected the data on which this study is based were (in
decreasing order of days spent in the field on our behalf): Liz Rozenberg (18
surveys, including one which she co-ordinated herself while the usual co-ordinators
were overseas), Andrea Spencer, Clare Morton, David Trudgeon, Wendy Trudgeon,
Alison Brown, Roni Starr, Grant Morton, Graeme MacAuslane, Maurice O’Connor,
Adrian Boyle, Belinda Forbes, Chris Sanderson, Greer Keenan, John Keenan,
Stewart Young, Mavis Russell, John Vines, Margaret Vines, Helen Macarthur, Jan
van de Kam, Zhang Keija, Loyd Berry and an anonymous Broome Bird Observatory
guest. Thank you all, for carrying a very worthwhile job very well indeed.
31
Shorebird disturbance in Roebuck Bay 2005-2006
8.
References
Kvist, A., Lindström, Å. Green, M., Piersma, T., Visser, G.H., 2001. Carrying large
fuel loads during sustained bird flight is cheaper than expected. Nature 413:
730-732.
Nudds, R.L., Bryant, D.M., 2000. The energetic costs of short flights in birds. Journal
of Experimental Biology 203: 1561-1572.
Rogers, D.I., P.F. Battley, T. Piersma, J. van Gils and K.G. Rogers. 2006a. High-tide
habitat choice: modelling the roost selection of shorebirds around a tropical
bay. Animal Behaviour. In press.
Rogers, D.I., T. Piersma and C.J. Hassell. 2006b. Roost Availability May Constrain
Shorebird Distribution: Exploring the Energetic Costs of Roosting and Disturbance
Around a Tropical Bay. Biological Conservation. In press.
Van de Kam, J., D.I. Rogers, T. Piersma, M. Lavaleye, G.B. Pearson and P. de Goiej.
2003. Life along land’s edge: wildlife on the shores of Roebuck Bay. WA
Department of Conservation and Land Management, Perth.
32
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 1: DISTURBANCE FORM
SITE:
Time
DATE:
Scan
Total No. of
(R/I)
shorebirds
Shorebirds flying
%
No.
OBSERVERS:
Alarm flight?
Cause of flight
Notes
(Y/N)
Scan: Use R for the scans done at Regular 10-minute intervals. Use I for irregular scans made at all other times (when any disturbance seen).
Total No of shorebirds: The number (species combined) in view from your position. Don’t include gulls and terns. Counts of each species are
useful if you have time; please put these on the separate count sheet.
Shorebirds flying: Record as % of shorebirds in view, or as a count – whatever is easiest. You only need to fill in one of the two columns.
Alarm flight: Yes or no. Alarm flights are flights obviously caused by disturbance; they are often characterised by sudden and steep take-off,
alarm calls and fast manoeuvering.
Cause of flight: People; BOPs (birds of prey); false alarm (e.g. if the birds get spooked by a tern flying overhead); unknown. If you are able to
give more detail (e.g. the species of bird of prey) please do this in the notes column.
33
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 1 (cont.): BEACH-USERS FORM
DATE:
Site
OBSERVERS:
Obs. period
Description of visitor/s
(Give first name or nickname if
Start
End
known)
Time of Beach-
Vehicle
users visit
Came
Went
No. of
people
Where
Activity
No. of
dogs
Bird
Interviewed
Disturbance
No.
34
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 1 (cont.; reverse side of beach-users form)
HINTS ON FILLING IN THE FORM (also, feel free to add extra notes):
1. Obs. Period = The time at which observations began, and when they finished.
2. Description of visitor/s. This column is there so we can identify cases where the same people are seen on different beaches, or are
recorded by both stationary and mobile teams. Name or vehicle description, if known, would be good; otherwise, pick out any attributes
that will work for the day.
3. Time of Beach-users visit – record arrival and departure time if possible so we can figure out how long they were on the beach.
4. Vehicles – number of vehicles (will usually be 1) and whether it parked by the road or came onto the beach.
5. Activity: Birdwatching, Rod-fishing, Net-fishing, Walking, Site-seeing, Other (please specify).
6. Bird disturbance – caused by these particular people. Classify as none, a little, or a lot – and feel free to add notes.
7. Interviewed? – No, don’t know, or yes. If yes, say whether the interview was done by the stationary or mobile team.
Example of a completed form:
Site
Obs. period
Start
End
Quarry B
9:00
13:00
Quarry B
9:00
13:00
Quarry B
9:00
13:00
Quarry B
9:00
13:00
1
2
Description of visitor/s
(Give first name or nickname
if known)
Young asian couple
with blue car
Tall bald man with red
t-shirt
Kimberley Birding
tour (George)
Family party including
4 kids
Time of Beachusers visit
Came
Went
Vehicle
Where
No. of
people
Activity
No. of
dogs
Bird
Disturbance
Interviewed
n
before
us
9:40
9:45
Road
1
2
Walking
0
Little
By Us
11:30
Road
1
0
0
None
By Chris
10:30
10:45
Road
1
4
Rodfishing
Birding
0
None
Dunno1
11:30
After
us
Beach
2
8
2
Lots
BBQ and
paddling
2
By Chris
Left before interviewed, but went towards Crab Creek and might have met other teams.
Most disturbance caused by dogs, all waders moved to east of beach.
35
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 1 (cont.): Interview form
36
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 2. Number of Alarm flights per hour on the Northern Beaches of Roebuck Bay during 2005-2006.
Month
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
Average
Weekend
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekday
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
Weekend
CS
ebb
CS
rise
CS
total
2.18
4.50
0.55
2.38
2.96
2.00
2.28
3.73
1.27
3.05
2.11
9.15
6.00
1.09
0.55
1.00
2.00
2.02
2.14
2.00
2.33
0.60
0.51
3.53
2.52
1.80
3.00
5.00
4.42
1.50
0.50
1.50
2.40
1.09
5.71
3.50
8.87
14.73
5.08
0.55
1.50
3.60
2.43
2.55
7.08
5.21
1.30
0.52
1.05
3.87
2.82
5.43
8.53
2.84
0.53
2.51
3.17
QB
ebb
QB
rise
QB
total
1.64
0.60
4.16
3.62
6.34
3.08
2.65
1.03
0.55
1.09
7.85
3.50
5.33
3.00
1.89
2.00
6.00
3.56
5.84
3.04
2.27
1.52
0.55
2.50
1.52
0.50
2.00
2.73
5.14
7.64
1.80
1.64
2.82
2.09
8.00
1.68
2.00
8.08
1.00
2.77
2.00
2.50
3.34
SB
ebb
5.22
0.60
SB
rise
4.50
0.55
2.80
0.47
0.39
SB
total
4.86
2.28
1.82
0.51
1.60
0.55
1.09
0.50
1.09
1.50
3.00
1.50
1.00
0.50
1.02
1.05
0.50
13.04
1.64
7.27
2.32
0.55
1.38
0.97
3.19
1.20
1.64
2.73
1.64
SV
rise
SV
total
5.45
2.04
2.20
3.57
7.86
SV
ebb
2.77
2.73
3.50
2.79
1.98
2.18
3.11
2.28
2.40
4.82
2.73
9.92
3.27
1.00
2.63
6.45
0.92
0.50
1.09
3.13
2.18
1.64
0.51
1.09
2.88
6.00
2.95
WB
ebb
WB
rise
WB
total
0.55
1.09
0.82
7.80
9.23
2.67
2.29
12.00
7.09
4.00
2.00
0.60
2.40
1.46
1.09
8.52
5.05
7.64
2.33
5.00
2.50
3.73
6.23
2.53
7.46
2.89
0.60
3.65
4.00
2.50
1.62
5.05
2.46
1.50
0.55
1.80
2.47
8.35
3.50
2.00
0.55
0.50
2.98
2.00
1.55
1.71
3.25
3.17
0.55
3.16
2.88
1.54
2.07
3.76
0.50
20.54
1.19
4.17
3.56
1.00
3.41
1.50
1.09
5.00
0.55
1.50
4.00
2.50
3.00
3.50
3.47
1.39
16.27
4.14
4.09
2.78
0.80
2.91
1.48
1.09
6.67
1.02
3.58
2.69
2.27
2.78
3.72
Total
4.86
1.92
2.41
0.85
4.96
3.93
3.08
8.46
3.11
1.91
1.36
2.25
4.03
1.50
1.56
4.27
3.23
2.74
4.46
4.33
2.27
1.70
2.88
3.13
37
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 2. (cont.). Amount of time spent in flight (minutes per high tide) on the Northern Beaches of Roebuck Bay during 2005-2006.
Month
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
Average
CS
Weekend ebb
Weekday
Weekend
0.0
Weekday
0.0
Weekend
36.0
Weekday
0.0
Weekend
5.3
Weekday
20.0
Weekend
19.7
Weekday
0.0
Weekend
0.0
Weekday
5.6
Weekend
6.1
Weekday
0.0
Weekend
0.0
Weekday
0.0
Weekend
5.3
Weekday
0.0
Weekend
0.0
Weekday
0.0
Weekend
21.6
Weekday
10.4
Weekend
0.0
Weekday
0.0
Weekend
5.4
CS
rise
CS
total
7.1
1.1
0.0
0.0
1.1
13.6
26.3
3.2
0.0
105.9
36.1
5.3
0.0
16.2
54.8
8.1
11.6
0.0
3.1
0.0
0.0
9.9
7.1
1.1
36.0
0.0
6.4
33.6
46.0
3.2
0.0
111.4
42.2
5.3
0.0
16.2
60.1
8.1
11.6
0.0
24.7
10.4
0.0
9.9
12.6
18.1
QB
ebb
QB
rise
0.0
0.0
0.0
0.0
0.0
QB
total
0.0
0.0
0.0
0.0
0.0
15.6
27.4
18.7
0.2
0.0
7.5
0.0
0.0
17.9
0.0
0.0
26.7
0.0
0.0
30.3
1.2
10.6
2.0
4.2
0.0
0.0
3.5
1.1
31.7
0.0
6.0
2.4
0.0
0.0
0.0
0.0
0.0
0.0
26.7
0.0
15.6
57.7
19.8
10.8
2.0
11.7
0.0
0.0
21.3
1.1
31.7
0.0
2.4
6.0
3.9
4.7
8.6
SB
ebb
17.1
0.0
1.1
0.0
SB
rise
0.0
40.0
0.0
0.0
SB
total
17.1
40.0
1.1
0.0
13.0
0.0
13.0
0.0
7.4
0.0
0.0
0.0
7.4
SV
ebb
SV
rise
9.6
0.0
0.0
SV
total
0.0
29.8
0.0
0.0
0.0
0.0
28.9
0.0
1.1
0.0
0.0
26.2
25.7
9.3
2.6
0.9
0.0
0.0
26.2
25.7
38.3
2.6
2.0
0.0
0.0
0.0
19.0
0.0
20.8
9.6
3.8
1.3
6.6
0.0
10.2
0.0
0.0
18.1
2.2
9.0
11.4
2.9
4.4
7.2
5.1
0.0
0.0
13.5
39.5
7.7
0.0
WB
ebb
WB
rise
WB
total
Total
9.6
29.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
25.1
0.0
56.0
0.0
0.8
14.2
46.6
29.7
1.7
13.5
27.6
3.5
14.2
66.7
0.9
17.1
14.2
6.4
7.2
0.0
1.6
15.5
24.2
9.5
7.3
71.4
19.8
5.1
4.4
20.3
24.7
11.6
14.9
13.4
16.9
5.8
15.6
7.3
12.5
14.5
0.0
8.8
11.6
2.4
0.0
4.0
0.0
0.0
8.1
0.0
19.0
13.5
60.3
17.2
3.8
1.3
6.6
8.8
21.9
2.4
0.0
22.1
2.2
9.0
19.5
0.8
12.0
28.9
10.0
0.0
1.4
18.9
0.0
14.2
9.4
0.9
25.1
0.0
56.0
0.0
0.0
2.2
17.7
19.7
1.7
12.1
8.7
3.5
0.0
57.3
0.0
5.2
10.3
4.0
8.5
38
Shorebird disturbance in Roebuck Bay 2005-2006
Appendix 3: Statistical details.
We modelled levels of disturbance using linear regression. We calculated two indices of
the level of disturbance for each day of fieldwork at each site (giving us a sample of 95
cases for analysis). The indices were:
Alarm flights per hour (given by the number of alarm flights observed, divided by the
duration of observation in minutes, multiplied by 6).
Time in flight (calculated using the “R” scans carried out every ten minutes). On each of
these scans, the total number of shorebirds present, and the number of those
shorebirds in flight was counted. Dividing the total number seen flying by the total
number seen in all, we calculated the percentage of birds in flight during the R
scans. We assumed that this percentage was representative of the percentage of
birds in flight during the high tide period from two hours before, to two hours after,
the peak of high tide.
Except where stated, we used the former index in our modelling. “Time in flight” is a closer
approximation to the energetic costs that birds experience on the roosts. However, the
indices were strongly correlated with one another, and there was less error involved in the
calculation of “alarm flights per hour”, as it was based on larger samples (many alarm
flights occurred between “R” scans).
“Alarm flights per hour” was treated as the dependent variable in our linear regression
models. Independent variables investigated were:
Month - categorical
Weekend - “0” if sampling was carried out on weekend; “1” if it was not)
Site - categorical
Tide state - categorical: “rising”, “peak” or “ebbing”
Tide height - peak height of tide on the day of sampling (m), obtained from tide timetables
Maximum shorebirds – The maximum number of shorebirds present at each site during
each period of observation
Average shorebirds – The mean number of shorebirds at each site during each full period
of observation
In initial models we treated rising and falling tides as separate data points (thus starting
with a file of 188 cases). We could not find any significant effect of tide state using models
based on this data set; any effect that might have existed was concealed by much greater
variation in other independent variables. Accordingly we simplified the models by
combining data from ebbing and rising tides on each day (thus working from a smaller data
set with 95 cases). In addition to being simpler, subsequent models had an equivalent or
superior predictive power to those obtained when rising and ebbing tides were separated.
“Maximum shorebirds” and “average shorebirds” were strongly correlated to one another,
and including both in models did not improve their predictive power. Models using
“average shorebirds” performed slightly better.
“Month” had a significant effect on the models. We found the models could be
considerably simplified, with little effect on their predictive power, if we combined some
months together. This was done in the final model for comparison with disturbance levels
observed in a previous study between 1997 and 2000. Output for this model is
summarised below.
39
Shorebird disturbance in Roebuck Bay 2005-2006
Dep Var: AFPH N: 95 Multiple R: 0.618590 Squared multiple R: 0.382653
Adjusted squared multiple R: 0.355216 Standard error of estimate: 2.091730
Effect
Constant
Tide height
Month May-July
Month August
Log av no. of shorebirds
Co-efficient
-8.772939
0.819942
2.096134
3.732294
0.702006
Std Error
3.187575
0.359804
0.795669
0.790545
0.133156
Std Coef
0.000000
0.208089
0.24646
0.399997
0.471128
Effect
Constant
Tide height
Month May-July
Month August
Log av no. of shorebirds
Coefficient
-8.772939
0.819942
2.096134
3.732294
0.702006
Lower 95%
-15.105613
0.105129
0.515398
2.161738
0.437469
Upper 95%
-2.440265
1.534754
3.676870
5.302850
0.966543
Tolerance
0.822668
0.943322
0.955591
0.858956
t
-2.75223
2.27886
2.63443
4.72116
5.27207
P (2 Tail)
0.00716
0.02504
0.00992
0.00001
0.00000
Analysis of Variance
Source
Regression
REsdiual
Sum-of-squares
244.078816
393.779980
df
4
90
Mean-Square
61.019704
4.375333
F-ratio
13.946299
P
0.000000
*** WARNING ***
Case
36 has large leverage (Leverage = 0.239768)
Case
87 is an outlier
(Studentized Residual = 5.349157)
Durbin-Watson D Statistic
First Order Autocorrelation
2.012753
-0.012811
40
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
Case Study of the Northward Fill Landfill
Geoffrey Webster
Waste Management Pacific (SA) Pty Ltd
12 Angle Vale Crescent, Burton SA 5110
Abstract
A great deal of change is currently occurring within the waste management industry in
South Australia with elevated standards being incorporated to those previously used
around the state. This paper explores how Waste Management Pacific is meeting and
exceeding these standards at the newly constructed landfill at Inkerman, 85 km north of
Adelaide, in particular focusing on the base liner, leachate collection system and
effective control of litter and birds at the site.
1
Introduction
Waste Management Pacific (SA) Pty Ltd (WMP) is a wholly owned subsidiary of Waste
Management NZ Ltd – a New Zealand registered public company, listed on both the
New Zealand and Australian Stock Exchanges and is the largest waste management
and resource recovery service provider in New Zealand.
WMP have been operating for nearly 20 years in New Zealand and commenced
operations in Australia in 2001. In March 2004 WMP expanded the Australian operations
into Adelaide, South Australia.
As a significant industry development in South Australia, WMP entered the SA
marketplace with the purchase of the Northward Fill landfill, Remove All Rubbish and the
winning of the tender with Wastecare SA for the design, construction and operation of a
Resource Recovery and Waste Transfer Facility in northern Adelaide.
The Northward Fill landfill is an above ground landfill which will provide a disposal facility
for Adelaide’s putrescible and inert waste for approximately 20 – 30 years with a waste
capacity of approximately 12,000,000 m3. The Northward Fill will receive processed
waste from EPA approved Resource Recovery and Waste Transfer Facilities, as part of
an overall waste management system, involving waste transfer stations which utilise
recycling and waste minimisation measures.
The site was approved through an extensive EIS process carried out during the late
nineties. EPA guidelines for the establishment of Major Solid Waste Landfill Depots
were in a draft form at the time of submitting the initial application, however the
Northward Fill was designed and constructed in accordance with Best Available Control
Technology (BACT) and incorporate Best Practice landfill operation in accordance with
an approved Landfill Environmental Management Plan (LEMP).
Page 1 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
As such it is one of the first facilities in the state to implement the high standard of
environmental and construction excellence being required of all waste management
facilities in South Australia.
In order to facilitate an understanding within industry, local government and government
of construction and management practices being incorporated at a recently approved
landfill, WMP has prepared this paper focusing on a few key elements of landfill
construction and design.
2
2.1
The Base Liner and Leachate Collection System
Design Features
A key component for effective and environmentally responsible construction and
operation of a waste management facility is the creation of a suitable barrier and
collection system for the prevention of potentially harmful materials from escaping into
the environment.
The landfill base will be lined with a low permeability layer to minimise leachate
percolating to the underlying groundwater system. The base of the liner is a minimum of
2 m from the underlying groundwater table with groundwater levels having been
determined through regular monitoring of levels measured in the network of site
groundwater monitoring bores.
In-situ Hindmarsh Clay, which underlies the site, will be recompacted to form a 1 m thick
layer with a permeability of less than or equal to 1 x 10–9 m/s. In order to achieve this in
the field, a compactive effort of greater than 98% standard dry density is to be achieved
with a moisture content varying between 0 and +3% of optimum.
In order to verify the ability of site materials to reach the required low permeability, a
number of test pits were excavated on the site prior to work commencing and five clay
samples were recovered and tested for permeability when recompacted. The results
from the tests are summarised in the table below
Table 1
Sample Permeability Results
Sample Location
Permeability (m/s)
TP2B
TP3
TP5
TP7
TP8
1.8 x 10-11
3.5 x 10-12
2.1 x 10-10
3.3 x 10-11
4.0 x 10-10
Compaction Density Ratio
%
95.5
100.0
97.5
100.0
98
The test results indicate that, when suitably compacted, the Hindmarsh Clay will exceed
the specification, having a permeability of less than 1 x 10-9 m/s. These results indicate
a permeability of 4 x 10-10 to 3.5 x 10-12 m/s, i.e. well below (or better) than required by
EPA Guidelines.
Page 2 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
The compatibility of the clay with landfill leachate was also investigated. Hindmarsh
Clay has illite and kaolin as the predominant clay minerals. Clays that consist of these
inactive minerals are relatively insensitive to leachate from municipal solid waste.
During construction, tests will be carried out, inter alia, to identify the mineralogy and
calcium carbonate content of the clay to select clays most suitable for the liner.
In some locations the base liner is above natural surface. In these areas the top layers
of sand and calcrete will be stripped and inspected by a suitably experienced
geotechnical engineer before placing and compacting at least 300 mm of site materials
which acts as the base from which to construct the clay liner.
The base liner is then constructed by compacting the clay materials in maximum 200
mm compacted thick layers. It will be tested for the specified permeability by standard
earthworks testing methods. Testing will be done by a NATA registered geotechnical
testing authority, to ensure that the required densities and moisture contents are
achieved, and compliance with specified densities and moisture requirements is
documented. Materials are selected to meet the specification requirements will be
identified by on-going site investigations.
The quality of works will be assured by the implementation of a Quality Assurance
testing program. This will be carried out by a NATA registered geotechnical testing
authority. Placement and compaction of clay lining material will be done in accordance
with AS 3798 under Level 1 supervision. This means that the geotechnical testing
authority has independent control of the testing program and certifies the work on
completion.
Liner sections that fail to meet target specification will be replaced or recompacted as
required to meet the specification. At least five compacted layers will be used to make
up the full liner with each layer being given Level 1 supervision. The potential of
through-liner flaws developing through five separately placed and compacted layers is
considered extremely low.
When constructing the clay liner, the final surface is profiled to incorporate drainage
slopes towards drainage lines of 2% and along drainage lines of 1%.
The liner system will be constructed over the base of the areas and extended up the
sides to provide full encapsulation. Side slopes for the in-ground portion of each cell
have been designed at 1:4 to facilitate liner construction.
A layer of plastic is placed on the clay immediately after the achievement of final design
levels. This will assist in keeping the underlying clays moist prior to the placement of
waste. The plastic cover will be sprayed with water from time to time as required to
prevent desiccation of the clay liner below.
A 300 mm layer of coarse stone (16 – 53 mm) with a minimum hydraulic conductivity of
1 x 10-3m/s will overlay the clay protection material. The coarse stone layer will act as a
porous drainage medium for leachate. A network of slotted HDPE pipes surrounded by
coarse stone will collect the leachate from the collection layer and drain it to the
collection sumps where it is then pumped to the leachate evaporation pond for
treatment.
Page 3 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
A filter geotextile will be used on top of the coarse stone to control biofouling of the
leachate drainage layer.
In addition to the sumps at the perimeter of the landfill, vertical sumps are incorporated
into the centre of the stage to allow for effective removal of leachate from cells which
drain to a low point within the body of the landfill In sump areas, a liner consisting of a
2mm HDPE and 700 mm of compacted clay (constructed in 200mm compacted layers
under Level 1 supervision (AS 3798 – 1996)) is to be constructed.
2.2
2.2.1
Construction Experiences
Low Permeability Liner
Key to protecting the environment from the potential impacts of a waste management
facility, a great deal of time and effort has gone into ensuring an effective lining system
has been installed at the site. During construction, a number of issues were
encountered which required effective management to ensure the productivity and quality
of the finished product met WMP (and EPA) requirements.
2.2.1.1 Up Front Testing
Consistency of the proposed materials to be used in the clay liner is required to ensure
required permeabilities can be achieved. As indicated previously, initial testing has
indicated that site clays produce a lining system that exceeds the requirements of the
EPA guidelines, however testing is necessary to ensure consistency of materials being
excavated from the field. Poorer quality clays are redirected for use elsewhere on the
site whilst good quality clay is identified and set aside for use in the liner.
A key construction cost is having an area of liner fail QA testing, requiring reworking or
even ripping out and replacement. It is critical that such events are kept to a minimum
as costs rapidly escalate if expenditure occurs for no tangible benefit. Pre-testing of
materials ensures that such failures will not occur due to clay quality concerns.
2.2.1.2 Construction Specification
Such site specific issues such as the nature of site clays are a key determinant as to
how construction should occur. Every site is unique and construction techniques should
be developed to suit the particular environment within which work is to occur.
WMP has identified this with respect to the construction specification of the clays where
material is to be placed at greater than 98% compaction with a moisture content within
the clay between 0 to +3% of the optimum moisture content (OMC). Experience on site
has shown that when working with moisture levels greater than about 1.5% above OMC,
site clays become overly wet and extremely difficult to work. Site machinery becomes
bogged and does more damage than active production. Following Stage 1 construction
works and associated testing, WMP has found that if a range of 0.5% to 1% wet of
optimum is targeted, a material which is workable and complies with our construction
specification is produced.
Page 4 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
Figure 1. Construction of Clay liner – Water Application and Clay Compaction
Construction techniques are such that compaction levels in excess of 100% are
frequently achieved with permeabilities regularly in the range of 1 x 10-11 m/s (or 100
times better than that required in the EPA guidelines) are achieved on site.
Such a small tolerance for moisture conditioning within construction though has resulted
in WMP, through Golder Associates and Tonkin Consulting, conducting a number of field
trials and an extensive literature review to develop an alternative construction
specification. This alternative construction specification has yet to be submitted to the
EPA for consideration however it is envisaged that such a submission will occur in the
near future.
Figure 2. Landfill compactors working on well compacted clay
2.2.1.3 Construction programming
Page 5 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
Planning when construction is to occur is just as important as planning how construction
will happen. Again this is site specific in nature however when working with clay, it
cannot be assumed that suitable construction conditions will exist all year round.
Plasticity of site clays is a significant factor that can lead to cracking which requires
careful monitoring and management to ensure a quality product when it comes time for
covering with the leachate collection system. Particularly prevalent during the January
and February periods, warm to hot conditions, combined with a decent breeze can
rapidly dry a placed liner causing significant desiccation.
Management measures including regular watering and rolling of prepared surfaces and
the incorporation of protection systems are required to minimise these impacts. It may
mean a water cart and roller are required to work the area on a continual basis however
if allowed to get out of control, subsequent damage to the liner may require significant
reworking or even replacement.
During the winter months, a different but equally frustrating situation is experienced
whereby minor rainfall events which would be welcomed during the summer months as a
means of keeping the clay moist, effectively halt work on site. Where summer conditions
rapidly dry out the effects of such rain, moisture on the liner surface during winter will
cause site clays to become untrafficable. As little as 5mm of rain will delay site activities
for up to 3 days and with heavy rainfalls such as those experienced during September
and October of this year, delays extending into weeks are experienced.
With construction equipment being unproductive during these times and air space being
consumed on a daily basis, pressure for effective construction from an operational and
cost basis rapidly mounts.
2.2.2
Clay Protection Membrane
As mentioned previously, protection of the finished clay surface is a key concern in
ensuring an effective environmental protection system is maintained.
WMP’s experience on site has been that the placement of a plastic membrane across
the surface of the clay following final trimming and rolling results in minimal cracking
occurring in the clay surface. After placement of the plastic, condensation can be seen
on the underside of the plastic. It appears that a micro environment with a high humidity
develops, preventing the clay from drying out and desiccating.
Such a protection measure is vulnerable to high winds blowing the plastic away
exposing the clay surface however this can be managed, and at an expense far less
than reworking of the clay surface.
2.2.3
Leachate Drainage System
Installation of rock for the leachate drainage system has required constant vigilance. In
particular the particle size distribution (PSD) of material to be used in the drainage
blanket has required careful management to ensure compliance with the 16-53mm
specification.
Page 6 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
When sourcing material for use in the drainage blanket, one must firstly identify a site
producing both chemically and physically suitable material. Consistency of material
production through the quarried seam can be readily identified and confidence gained
that material generated at the site will meet the specification. Issues have been
identified, however, when testing is carried out on the floor of the landfill cell and
excessive fines and stone chips are located in isolated areas requiring remediation.
This has caused a great deal of consternation as if a test is carried out at the quarry or
even in site stockpiles, PSD test results indicate that the aggregate is suitable for use on
the floor.
WMP has identified a number of reasons why this may be occurring including the
following:
Between rock production and its installation on the landfill floor, there are
numerous handling procedures that occur, from stockpiling at the quarry, to
delivery to the landfill, to stockpiling on site to rehandling to the landfill floor.
Each time the material is handled in such a way, there is the potential for the rock
to be fractured and produce chips and or dust.
If rock crushing occurs during rain events, often a layer of mud (dust that would
otherwise have blown away in dry conditions) will form around the aggregate.
When this material subsequently dries out, it will give the impression of a high
level of fines within the aggregate.
During travel from either the quarry to the landfill or from site stockpiles to the
landfill floor, vibrations and general jolting within the truck body will cause smaller
particles to migrate to the base of the vehicle. When subsequently unloaded this
results in a slug of poor quality material in a concentrated area.
When material is stockpiled on site during rain periods, top layers of aggregate
will have any dust washed of it and transported to the lower portions of the
stockpile. This causes fines concentrations in excess of that allowed under the
construction specification.
Achieving the desired quality of material on the floor of the landfill has resulted in WMP
commissioning Golder Associates to carry out independent inspections and tests to
ensure the above issues do not impact upon the effectiveness of the leachate drainage
blanket.
Achieving the desired outcome on the floor of the landfill has taken considerable effort
and dedication from both site staff and Golder Associates. Tight quality assurance
practices are enacted to manage the risks including the following
As soon as material comes onto site with a WMP representative inspecting
material as it is deposited and pushed into the site stockpile.
When taking aggregate from the stockpile to the cell floor the loading operator is
selective in the material to be used to ensure any obviously contaminated
Page 7 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
December 2005
material is not loaded out and is set aside for either use elsewhere on site or
reprocessing. This is particularly relevant for the bottom 300mm of the stockpile
which often contains a high proportion of fines. This material is left on the ground
and collected later for rescreening.
When depositing material on the floor, the residual material from the floor of the
truck is left in the vehicle and set aside for future rescreening.
Site staff as well as a Golder Associates representative walk across the top of
the laid aggregate a number of times each day looking for tell-tale signs of high
concentrations of fines/chips. Any identified areas are remediated there and
then.
QA testing carried out on the floor to ensure that the finished product complies
with the requirements of the specification.
Incorporation of these and other control techniques has enabled WMP to install
thousands of square metres of drainage blanket at the Northward Fill landfill, all to a
standard meeting or exceeding SA EPA requirements.
2.2.4
Bidim Layer
The filter geotextile used at the Northward Fill landfill is a Bidim A24. It is still early in the
life of the landfill and WMP is not able to provide an assessment as to the effectiveness
of the geotextile layer in controlling the ingress of fines into the drainage blanket, or the
control of biofouling. We do know that leachate has been pumped from stage 1
(indicating an effective drainage system is in place) and that leachate pumped from
stage 1 sumps has been relatively clean and free from either sediment or biomass.
Installation of a geotextile layer has proven to be relatively simple however during windy
conditions the Bidim has been known to catch the wind and be blown from its placed
position on the aggregate. In order to combat this, hessian bags filled with aggregate are
used to weigh down the material.
3
3.1
Operational Experience at the Site using a Litter Tent
Description of the Litter Tent
To ensure active control of litter, a litter tent system has been utilised at the site. General
design data of the litter tent system is provided below.
Span width (mast tip – mast tip):
Base details:
Mast details:
43 m
Construction material: steel or concrete
Dimensions: 5.0 m width, 3.0 m length
Mounted on four rollers, 0.6 m diameter
Rollers constructed from concrete or steel
Construction material: steel
Height: 10.0 m – 12.0 m
Page 8 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
Rigging details:
Net details:
December 2005
2 mast head stays, 2 intermediate stays
Construction material: UV stabilised nylon cord
Mesh dimensions: 85 mm x 85 mm
The number of mast/base units per tent to be assembled will depend on the area to be
enclosed. Two litter tent systems have been established at the Northward Fill. Each
litter tent has ten mast/base units, five on each side of the cell. The total area enclosed
by this arrangement is approximately 1,300 m2 per unit.
3.2
Daily Operating Details
As the cell area covered by the net is progressively filled, the net assembly is moved
forward so that waste is always being unloaded within the net enclosure. Movement of
the net is achieved by attaching a dozer or landfill compactor to the front of each row of
bases/masts, and moving forward the required distance. The net remains in position,
however the lowest 2 m of the net is rolled up to protect it from damage.
Having two tent assemblies will ensure that one of the tents is always available to
receive waste. As wastes are unloaded, they are spread and compacted by landfill
compactors in lifts. Each lift has a compacted thickness of 1.5 m to 3 m. This ensures
that the final density achieved is greater than the minimum of 700 kg/m3 as required by
the EPA.
Up to 3 waste vehicles can be unloaded within the Somernet without affecting
operations. A fourth vehicle can also be unloaded at the same time however operations
get cramped within the net at this time.
Figure 3. Vehicles Unloading within the Somernet.
Page 9 of 10
Australian Geomechanics Society – SA Chapter
Seminar on Geotechnical Aspects of Landfills
3.2.1
December 2005
Effectiveness of Controlling Litter and Birds
The primary reason for implementing the netting system at the site is to provide an
effective means for the control of litter and birds at the site. WMP’s experience has
been that the netting system is highly effective in such control, even under extreme
weather conditions.
Since opening, the site has experienced gale force winds on a number of occasions. In
every instance, disposal of waste within the net has continued with minimal litter escape.
It has proven itself to be a valuable tool in the control of litter.
Seagulls, a primary pest at South Australian waste management facilities, are not a
nuisance at the site. Overseas experience has been that if birds are near waste
disposal activities, they are reluctant to approach the net and soon leave the site. Having
operated for almost a year as at the time of writing this paper, WMP would have
expected that if birds were to make a nuisance of themselves, such an impact would
already be being experienced.
4
Conclusion
WMP believes that there are numerous challenges still to be faced at the Northward Fill
landfill to ensure effective construction techniques are implemented at the site, whilst still
meeting and exceeding EPA requirements for environmental protection. Such
challenges are experienced at every site in their own unique way and require carefully
thought out management practices to ensure compliance with corporate and regulatory
goals.
It must be noted that in achieving these high standards, significant costs are being
incurred and proponents must be vigilant otherwise such costs could rapidly spiral out of
control.
Page 10 of 10
Northward Fill
Environmentally Sustainable Solutions
> Transpacific’s Northward Fill facility serves
as the final destination for residual waste that
cannot be recovered, recycled or reused.
Located at Inkerman, 80 km north of Adelaide, the
highly engineered facility has been in operation since
2005 and has been acknowledged for setting the
benchmark in landfill design and operation.
With a planned operational life of 40 years, the
importance of delivering a safe, convenient and
environmentally compliant waste disposal solution is
paramount.
As part of our sustainable waste management
philosophy, Transpacific endeavours to minimise any
environmental impact of residual waste disposed at
the facility through a range of best practice
technologies and environmental controls.
Northward Fill’s development and operation is a
result of thorough planning, innovative technology,
and strong community engagement. The facility has
been developed with best practice at front of mind.
Northward Fill features:








Engineered lined disposal cells
Engineered leachate management solutions
Netting control system for litter protection
Odour and pest control
Thorough environmental monitoring
Vegetation and restoration program
Specialist, well buffered location
Winner of multiple awards
Environmental Protection and Controls
A range of environmental protection controls are
used to ensure the facility operates in a convenient,
safe and environmentally compliant way.
Engineered lined disposal cells: The regular
disposal cells are lined with an impermeable clay
barrier, protecting the groundwater and
environment. A specially designed and constructed
disposal cell can receive low level contaminated
waste. This cell features a triple barrier liner
system, along with an early detection system in
case one of the barriers is compromised. Together,
these provide an extremely safe disposal option for
low level contaminated waste.
Engineered leachate management solutions:
Leachate generated from the waste mass is
directed to one of many extraction wells within the
landfill. The leachate is then pumped to lined
evaporation ponds where it is treated via
evaporation.
Netting system: An extensive moveable netting
system is used to manage litter and pest control.
This system was purpose-built to cover the working
portion of the landfill and ensures all waste is
retained within the disposal zone and pests are
kept out.
Environmental monitoring: Extensive monitoring
and control systems are in place to ensure the
facility continues to exceed strict environmental
guidelines. To further reduce pests and potential
odours, waste received at the site is covered with a
layer of soil at the end of each day.
Waste Services
A number of bores located throughout the site are
used to provide ongoing monitoring of soil, ground
water and landfill gas conditions. This monitoring is
supported by extensive stormwater, erosion, air
emission, noise, dust and fire control systems.
Northward Fill has extensive capacity to accept the
following types of waste:
Waste Accepted
Not Accepted
Vegetation program: A vegetation program
manages erosion by planting grain crops on land not
currently being used by the facility, helping to
control the spread of weeds and improve the visual
aesthetics of the amenity.
 Domestic waste
 Friable Asbestos
 Commercial/Industrial
waste
 High level
contaminated soils
 Municipal waste
 Listed waste (limited)
 Green waste
The facility’s location was chosen to meet specialist
requirements – situated on a major transport route,
the location is relatively hidden from public view,
experiences a low annual rainfall and has access to
its own on-site clay deposits, an important resource
in the construction of landfill cells.
 Kerbside collected
green waste
 Liquid wastes and
sludges
Multiple award winner: Transpacific is one of
Australia and New Zealand’s leading owners and
operators of landfill sites and has extensive
expertise in landfill design, development and
operational management. Northward Fill site has
won the following awards:
> Silver award winner - WMAA National Landfill
Excellence Awards in 2007.
> Winner: Case Earth Awards (SA) for
Environmental Excellence & Construction
Excellence in 2005.
 Soluble chemical waste
 Construction and
demolition waste
(C & D waste)
 Triple interceptor
waste
 Clean fill
 Automotive batteries
 Intermediate Landfill
Cover
 Non-Friable Asbestos
 Quarantine waste
 Grease trap waste
 Whole tyres
 Motor vehicle bodies &
chassis
 CCA treated timber
 Low level
contaminated soils
 Liquid treatment plant
residues
 Shredded tyres
About Transpacific
Transpacific is a modern, dynamic and driven industry leader. Our philosophy is that all waste is a resource and our
aim is to incorporate recovery, recycling and reuse throughout all our operations and those of our clients.
Transpacific is strongly committed to the safe and responsible management of waste, regulatory compliance, and
the protection and enhancement of the environment.
Contact
For more information, contact the Northward Fill Office:
(08) 8867 1355
B I O L O G I CA L C O N S E RVAT I O N
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/biocon
Roost availability may constrain shorebird distribution:
Exploring the energetic costs of roosting and disturbance
around a tropical bay
Danny I. Rogersa,*, Theunis Piersmab,c, Chris J. Hasselld
a
Johnstone Centre, Charles Sturt University, P.O. Box 789, Albury, NSW 2640, Australia
Department of Marine Ecology and Evolution, Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg,
Texel, The Netherlands
c
Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 45, 9750 AA Haren,
The Netherlands
d
Turnstone Nature Discovery, P.O. Box 3089, Broome, WA 6725, Australia
b
A R T I C L E I N F O
A B S T R A C T
Article history:
High tides force shorebirds from their intertidal feeding areas to refuges known as roosts.
Received 24 February 2006
This paper explores the energetic costs of roost disturbance of great knot (Calidris tenuiros-
Received in revised form
tris) and red knot (C. canutus) at Roebuck Bay, North-western Australia, assessing
31 May 2006
disturbance levels at different roost sites through direct observation and automatic
Accepted 10 June 2006
radio-telemetry, and applying physiological equations and predictive roost choice models
Available online 5 September 2006
to estimate energetic costs of disturbance through a complete tidal cycle. The study area
had a variety of roosts, but use of each was constrained by conditions of tide and time.
Keywords:
The roost most suitable for shorebirds on daytime high tides of intermediate height expe-
Sandpipers Calidris sp
rienced high levels of disturbance from both natural sources (birds of prey) and humans.
Coastal wetlands
Flight costs caused by disturbance at this site exceeded the costs of flying to and roosting
Human disturbance
at the nearest alternative roost, 25 km away. However, shorebirds did not roost at the alter-
Roosting behavior
nate site, possibly because of the risk of heat stress in a prolonged flight in tropical condi-
Focal point regulation
tions. Increases in disturbance levels at just one of the roost sites of Roebuck Bay would
Roebuck Bay
increase energetic costs substantially, and could easily reach the point at which feeding
areas accessed from this roost cannot be used without incurring a net energy deficit. Roost
availability can therefore limit access to feeding areas and hence limit population size.
Adequate provision and management of roost sites is accordingly an important consideration in conservation of sites used by coastal shorebirds.
2006 Elsevier Ltd. All rights reserved.
1.
Introduction
The distribution of animals is usually thought to be restricted
by the occurrence of good feeding areas, with predators and
disease organisms determining the quality of such areas in
addition to resource abundance (Newton, 1998). However,
many animals use feeding areas for only part of the day and
at other times rely on alternative areas to roost and loaf. In tidal areas shorebirds have to leave their intertidal feeding
areas for high tide roosts. Shorebirds are particular in their
* Corresponding author: Permanent address: 340 Nink’s Road, St Andrews, Victoria 3761, Australia.
E-mail addresses: [email protected] (D.I. Rogers), [email protected] (T. Piersma), [email protected] (C.J. Hassell).
0006-3207/$ - see front matter 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.biocon.2006.06.007
226
B I O L O G I C A L C O N S E RVAT I O N
choice of such roosts (Piersma et al., 1993; Luı́s et al., 2001;
Rogers, 2003), preferring accessible sites where birds are safe
and not thermally stressed. Accessibility is a function of the
distance from the feeding grounds. Safety is a function of
the risk of predator attack, perhaps in combination with human disturbance (Rosa et al., 2006). Thermal stress, either because of wind and cold induced rises in maintenance costs
(Wiersma and Piersma, 1994) or excessive heat load (Battley
et al., 2003), is a function of the geomorphological features
of a place, and may also be influenced by human disturbance.
This study examines the importance of having a range of
roosting options available for differing conditions of tide, time
of day and season. Using a tropical system, Roebuck Bay in
north-western Australia, we build on an analysis of the
choices made by two species of shorebird (Rogers et al., in
press). Our interest in these roosting options is twofold. First,
we would like to examine whether the options available to
shorebirds in this particular setting are secure in the face of
increasing levels of human disturbance. Secondly, we would
like to know if roost availability can limit access to feeding
grounds, an issue that has received little attention in shorebirds despite the finding that foraging itineraries of red knot
Calidris canutus and dunlin C. alpina are influenced by the
proximity of roosts (Van Gils et al., 2006; Dias et al., 2006).
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
Several studies have shown that foraging success, and hence
potentially the survival, of shorebirds can be limited by interference (Triplet et al., 1999; Van Gils and Piersma, 2004) or
excessive depletion of their prey (O’Connor and Brown,
1977; Van Gils et al., 2003; Zharikov and Skilleter, 2003).
Roost-constrained access to feeding grounds could therefore
interact with density-dependent limits on food availability
to regulate shorebird numbers even if the food supply is widespread, a mechanism termed ‘‘focal point regulation’’ by Newton (1998).
The two study species, red knot and great knot Calidris tenuirostris, are large migratory sandpipers that breed in Arctic
tundra. In the non-breeding season both species occur in
large flocks, and are restricted to coastal habitats, where they
specialise in hunting buried molluscs in intertidal mud- and
sandflats (Tulp and De Goeij, 1994; Van Gils et al., 2003). At
high tide they characteristically roost in flocks on the ground
in open habitats, taking to the air if threatened by potential
predators. Both species are lean for most of their non-breeding period in Australia, but mass increases to about 150% in
Feb.–Apr as they accumulate the stores required to fuel northwards migration (Battley et al., 2004; Piersma et al., 2005).
Roebuck Bay (18 S, 122 E; Fig. 1), on the north-west coast
of Australia, has large intertidal flats that provide feeding
extent of closed mangroves
intertidal zone
western open
mangroves
Cable
Beach
Northern Beaches
3
2
western
flats
salt scold
open mangroves
N
1
4
Crab Creek
flats
open
mangroves
Town
Beach
saltpans
10
SPRING
height of tide (m)
8
Bush
Point
time of daytime high tide
KING
INT
20
18
height
of tide
16
6
NEAP
14
4
12
2
10
0
8
hours since midnight
5 km
6
-2
0
7
14
21
28
35
42
49
days since 26 Feb
Fig. 1 – Map of the Roebuck Bay study site, adapted from aerial photographs. Feeding sites considered in this study are
denoted with white-centred dots and numbered; from left to right: Town Beach, Dampier Flats, Fall Point and Crab Creek.
Roosting habitats are marked in black and labeled. Inset: Amplitude of tides in the bay (plotted against the left-hand y-axis)
through the study period, 26 Feb. to 15 April. Times of the peak daytime high tides are plotted against the right-hand y-axis.
Grey shading depicts high tides classified as springs (8.3–8.95 m) and neaps (>6.0 m); intermediate and king tides are also
shown. Lunar phases are shown at the bottom of the graph.
B I O L O G I C A L C O N S E RVAT I O N
areas for internationally significant numbers of 20 migratory
shorebird species (Rogers et al., 2003). It has a hot tropical
climate, and extensive mangroves surround much of the
bay (Fig. 1). Mangroves are usually too densely vegetated to
be suitable roosts for coastal shorebirds (Zwarts, 1988). As a
result, shorebird roosts of Roebuck Bay are restricted to a
few discrete sites (Fig. 1): small mangrove clearings about
100 m in diameter (Open Mangroves and Western Open Mangroves); supratidal claypans east of the bay (Saltpans); raised
mudflats only exposed on high tides during neaps (Western
Flats, Crab Creek Flats); and beaches (Bush Point, Cable Beach
and the Northern Beaches). Sparsely vegetated white dunes
back Cable Beach and Bush Point. The Northern Beaches are
narrower, are backed by vegetated dunes and low laterite
cliffs and have a few small adjacent sea-stacks sometimes
used by roosting shorebirds; they are internationally renowned as a shorebird-viewing site (Rogers et al., 2003). The
adjacent town of Broome has a thriving tourist industry and
is growing rapidly, increasing the risk of shorebird disturbance on the Northern Beaches.
2.
Methods
2.1.
Temporal variation in the roosting option set
Rogers et al. (in press) used a radio-telemetry study at Roebuck Bay to calibrate simple bounds-based models of local
roost choice in great and red knots. These models were applied in this paper to assess whether roosts were potentially
suitable. The models assume that knots roost at the closest
site to their low-tide feeding area, provided that at these
roosts, threshold values for certain environmental attributes
(Table 1) are met. By day, environmental thresholds were: (1)
a wet substrate, as sites with dry substrates had too warm a
microclimate for roosting shorebirds; (2) nearest tall cover
that should be at least 10–59 m from the roost (predictive success of models on non-neap tides, 63.5% for Great Knot, 70.0%
for Red Knot; predictive success of models on neap tides,
90.6% for Great Knot, 80.3% for Red Knot). At night, microclimate did not affect the bounds models (it was cool at all sites
in the absence of direct solar radiation); thresholds were that
the nearest tall cover should be at least 10–59 m from the
227
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
roost and that the background colour at the roost should
not be dark (predictive success of models on non-neap tides,
59.9% for great knot, 64.6% for red knot; predictive success of
models on neap tides, 92.3% for great knot, 80.1% for red
knot).
2.2.
Disturbance
The frequency of disturbance was measured directly at five
sites (final column of Table 2) in October 1997, March and August 1998, and October 2000, by watching roosting flocks from
concealed positions. Each time a flock or part of flock took to
the air, the time and number of flying shorebirds was noted.
Flights were classified as alarm flights if birds towered and
gave alarm calls. The cause of observed disturbances was recorded if identified. The percentage of shorebirds that were
airborne was recorded at regular 5-min or 10-min intervals
throughout the observation periods, and pooled data from
these observations were used to estimate the percentage of
the high tide period that was spent airborne due to disturbance. At the Northern Beaches a multiple linear regression
showed the proportion of shorebirds in alarm flights per
half-hour of observation to be significantly related to both
tide height (P = 0.0028) and a categorical variable describing
whether the tide was rising or falling (P = 0.0029; R2 = 0.641,
n = 17), with birds being more likely to be disturbed on a rising
tide. In estimating the number of disturbances and amount of
time spent in flight due to disturbance throughout a high tide
period at this site, it was therefore necessary to account for
the number of observations made on rising and falling tides.
At other roost sites estimates of the number of alarm flights
per hour were based on study days in which disturbance
was recorded systematically throughout a high tide period;
the number of observations made on rising and falling tides
was therefore equal and no correction was needed.
These quantified observations were not made at all roost
sites in Roebuck Bay, many of which were not readily accessible to human observers or were otherwise unsuitable for systematic disturbance observations. An ordinal a priori
assessment of disturbance levels at other sites (Table 2) was
made for all Roebuck Bay roosts on the basis of unquantified
observations made while birdwatching regularly in the region
Table 1 – Attributes of roost sites of Roebuck Bay
Tide height (m)
Northern beaches
Crab creek flats
Cable beach
Bush point
Western flats
Western open mangroves
Open mangroves
Saltpans
Town beach
Back-ground
colour
All
Int.
Pale
Pale
Pale
Int.
Dark
Dark
Pale
Int.
Distance to tall cover; daytime substrate temperature
Neap (<6 m)
Intermediate (6.0–8.2 m)
Low Spring (8.3–8.9 m)
King (P9 m)
60–199 m; cool
>200 m; cool
>200 m; cool
>200 m; cool
1–10 m; cool
10–59 m; hot
10–59 m; hot
>200 m; hot
60–199 m; cool
10–59 m; cool
<1 m; flooded
60–199 m; cool
>200 m; cool
<1 m; flooded
10–59 m; hot
10–59 m; hot
>200 m; hot
10–59 m; cool
1–10 m; cool
<1 m; flooded
10–59 m; cool
60–199 m; cool
<1 m; flooded
10–59 m; int.
10–59 m; cool
>200 m; cool
10–59 m; cool
1–10 m; int.
<1 m; flooded
10–59 m; cool
60–199 m; cool
<1 m; flooded
10–59 m; cool
1–10 m; int.
>200 m; cool
10–59 m; cool
Background colour was scored as pale, intermediate (Int.) or dark. Substrate temperature was scored as wet, intermediate (in situations where
it was drying out or the wet area was small) or dry; sites scored as flooded were too deeply immersed for shorebirds to roost.
228
B I O L O G I C A L C O N S E RVAT I O N
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
Table 2 – Parameters and formulae used in models
Site
Disturbance level
% of radio-signals
No. of
Alarm flights per hour,
(a priori classification)
interrupted
radio records time spent in alarm flights per tide
Cable beach – day
Town beach – day
Northern beaches – day
Open mangroves – night
Northern beaches – night
Open mangroves – day
Town beach- night
Western flats -day
Western flats -night
Western open mangroves – night
Western open mangroves – day
Bush Point – day
Bush Point – night
Crab Creek Flats – day
Crab Creek Flats – night
Saltpans – day
Cable Beach – night
Saltpans – night
Very high
High
High
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Low
Low
Low
Low
Low
Low
Low
over several years (DIR, CJH, unpubl. data). These classifications were compared with data obtained in a radio-telemetry
study carried out from Feb. to Apr. 2000, reported in detail by
Battley et al. (2004) and Rogers et al. (in press). The study
involved 25 great and 23 red knots with a 1.8 g Holohil BD2 ratio-transmitter superglued to their rumps. Their local movements were monitored with an array of 14 continuously
operating automatic radio-tracking stations sited at the key
roost sites of Roebuck Bay. The stations had a short radioreception range (0.7–1.0 km) and individuals were treated as
being present at a station if the signal strength was P1.4
times the background noise. In constructing disturbance indices for this paper, a bird at a specific roost was considered to
have been disturbed if its radio-signal was interrupted during
within an hour of high water (i.e. if it moved to another roost
during high tide, or if its signal stopped and later resumed at
the same site). Sites with the highest percentage of interrupted radio-signals were assumed to be the most heavily
disturbed.
2.3.
Disturbance costs
Roost choice costs were simulated for great and red knots
from four feeding sites in northern Roebuck Bay (Fig. 1), all
of which are regularly used by one or both knot species (Rogers, 1999, unpubl. data). In theory a roost site would be unsuitable if the energetic costs of roosting there exceeded energy
intake minus maintenance requirements. However, energy
deficits incurred while roosting on a specific tide might be offset by surpluses made on other tides. The roost choice models
(summarised above) were therefore used to predict where
great and red knots from the four selected feeding sites would
roost on high tide, through a complete cycle of 28 low and 28
high tides. It was assumed that during non-neap tides, individuals would be faithful to only one feeding area, and that
on neap tides they would move to the Crab Creek Flats in
the east of the bay (Fig. 1); this movement pattern was followed regularly by the knots radio-tracked by Rogers et al.
(in press). The average number of neap (<6 m), intermediate
89.5%
81.2%
66.7%
63.6%
58.3%
50%
50%
50.0%
46.4%
43.5%
30.0%
29.7%
25.9%
9.0%
5.2%
3.1%
0
143
617
9
165
115
0
2
2
4
69
23
70
118
139
89
677
159
3.36 (29 h obs.), 30.1 mins
0.90 (10 h obs.), 7.8 mins
0 (9 h obs.)
0 (5 h obs.)
0 (10 h obs.)
(6–8.2 m), spring (8.3–9 m) and king (>9 m) high tides per cycle
was calculated from a year (2000) of tide-height data (National
Tidal Centre, Australian Bureau of Meteorology). The landward edge of the intertidal flats of Roebuck Bay corresponds
well with mean sea level (pers. obs.), so low and high tide
periods were treated as being of equal duration, 370.1 min.
Suitability of some roost sites in Roebuck Bay is influenced
by heavy rainfall; for the simulations herein it was assumed
the tidal cycle occurred in a rainless period (typical of Roebuck Bay, except in the wet season from about December to
April).
Parameters and formulae used to calculate costs of maintenance and roost flights are summarised in Table 3. Body
mass and Basal Metabolic Rate have been measured in great
knot in Roebuck Bay, as has body mass of red knot; Basal Metabolic Rate of red knot in the bay was calculated by scaling
down from the great knot estimates using an interspecific
mass exponent of 0.71. Remaining parameters and formulae
were obtained from published studies in laboratories or extralimital sites. Thermoneutrality was assumed at all times, as
operative temperatures of knots in the study area are typically in the thermoneutral zone (Wiersma and Piersma,
1994; Piersma et al., 1995), except in hot conditions when
knots avoid overheating by seeking roosts with cool microclimates (Rogers et al., in press), a preference accounted for by
the roost choice models. However, a correction was included
for heat loss to ingested cold water during foraging, modifying the equation of Piersma et al. (2003a). The original equation included heat loss of 0.58 W in water of 15 C, and this
was corrected by a factor of 0.792, acting on the assumptions
that all such heat loss was conductive, and that average surface- and pore water temperature in Roebuck Bay mudflats
was 28 C (unpubl. data). As the birds in the study site were
living under thermoneutral conditions, we additionally
assumed that all cost factors were additive (Van Gils et al.,
2006).
Durations of commuting flights from the four selected
feeding sites to the different roosts of Roebuck Bay were calculated assuming direct flights that were regarded as occur-
B I O L O G I C A L C O N S E RVAT I O N
229
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
Table 3 – Site-specific likelihood of disturbance at the roosts of Roebuck Bay, ordered approximately from most to least
highly disturbed, with night roosts shaded grey
Parameter
Mass (Mb)
Flight speed
Power input (Pin) in flight
Basal metabolic rate (BMR, in W)
Cost of sleeping (KJ)
Cost of active rest (KJ)
Cost of foraging (KJ)
Cost of digestion (KJ)
Assumptions and calculations
Source
Great kot lean mass = 147.7 g
Great knot departure mass = 240 g
Red knot lean mass = 105 g
Red knot departure mass = 165 g
54 km h1
Long flights: P in = 0.38 + 0.35log10Mb
Short flights: P in ¼ 250:05 M b0:8741
2.57 + 1.24(log10Mb)
BMR · time spent sleeping (in seconds)
BMR · 1.659
[(BMR · 1.659) + (BMR · 0.613)] · time spent foraging (in seconds)
(BMR · 1.105) · time spent foraging (in seconds) · 0.792
Higgins and Davies (1996)
Higgins and Davies (1996)
Piersma et al. (2005)
Piersma et al. (2005)
Kvist et al. (2001)
Kvist et al. (2001)
Nudds and Bryant (2000)
Battley et al. (2001)
Piersma et al. (2003a)
Piersma et al. (2003a)
Piersma et al. (2003a)
Piersma et al. (2003a)
ring during the high tide period. Alarm flights, in which both
species of knot take off rapidly and climb to considerable
height (often >100 m, pers. obs.) were assumed to be more
costly than steady flight (Hambly et al., 2004). Their costs were
calculated using the allometric equation for short flights of
Nudds and Bryant (2000), which predicted the short-flight
costs of our study species to be 3.03 times greater than steady-state flight in lean red knots, 3.58 times greater than steady-state flight in lean great knots. This equation has not been
calibrated on birds >150 g, so may not be perfectly suitable for
red and great knots approaching departure mass. The alarm
flights of knots include bursts of high speed, rapid changes
in direction and substantial height gain, so our suspicion is
that their costs are more likely to exceed than to fall short
of the costs predicted by the equation. In another respect
the assessment of disturbance costs was also conservative;
disturbance may cause increased heartbeat rate and metabolic costs without actually forcing birds to take flight (Giese,
1998), and our models did not attempt any correction for this
effect.
The amount of time spent sleeping, in active rest (e.g.
standing, walking or preening) or foraging was estimated
through activity scans made at feeding and roosting habitats
in Roebuck Bay.
3.
Results
3.1.
Temporal variation in the roosting option set
The suitability of individual roost sites used by the great and
red knots of northern Roebuck Bay (Fig. 1) varied according to
whether it was day or night, and with tide and climate conditions (Rogers et al., in press). In general usage of roosts corresponded well with that predicted by the bounds models (Table
4). The Northern Beaches were used more than expected on
spring and king tides because some knots roosted on a few
Table 4 – Suitability of roost sites, Feb.–Apr. 2000, in different conditions of tide, climate and time
Conditions and
no. of records
Crab creek
flats
Day (dry)
Neap (112)
Intermediate (254)
Spring (193)
King (0)
90.2%
0%
0%
–
Day (wet)
Neap (75)
Intermediate (225)
Spring (118)
King (111)
Night
Neap (153)
Intermediate (464)
Spring (88)
King (0)
Western
flats
Northern
beaches
Town
beach
Cable
beach
1.8%
0%
0%
–
7.1%
85.0%
65.3%
–
0.9%
5.1%
5.2%
–
0%
0%
0%
–
0%
0%
0%
–
0%
0.4%
11.9%
–
0%
4.3%
16.1%
–
–
81.3%
0%
0%
0%
2.7%
0%
0%
0%
16.0%
45.3%
40.7%
33.3%
0%
7.1%
5.9%
20.7%
0%
0%
0%
0%
0%
0%
0%
0%
0%
11.6%
16.1%
27.9%
0%
3.1%
18.6%
0%
0%
32.9%
18.6%
18.0%
86.3%
0%
0%
–
0.7%
0%
0%
–
3.9%
11.0%
27.3%
–
0%
0.2%
0%
–
0.7%
1.1%
4.5%
–
0%
1.3%
2.3%
–
0%
0%
0%
–
0%
27.8%
39.8%
–
8.5%
58.6%
26.1%
–
Bush
point
Western open
mangroves
Open
mangroves
Saltpans
0%
5.1%
1.6%
Unshaded cells depict potentially suitable roost sites. Cells shaded dark grey depict flooded sites where roosting was impossible. Cells shaded
light grey depict other cases where climate, distance from tall cover or background colour were outside the thresholds of bounds models
(Rogers et al., in press). Percentages of radio-tagged birds found at specific roosts in different tide conditions are shown, with the number of
total cases given in parentheses in the first column.
230
B I O L O G I C A L C O N S E RVAT I O N
3.2.
Disturbance
Classifications of roost disturbance levels made through
opportunistic observations corresponded well with more rigorous data obtained through radio-telemetry or systematic
observation (Table 2), suggesting our assessment of relative
disturbance levels of the roosts is adequate. The most heavily
disturbed daytime roosts were beaches that are also the
roosts most easily and often visited by humans (pers. obs.).
In particular, Cable Beach (the most frequently used roost at
night) is a popular tourist resort and the lack of radio-records
from the site by day may have been due to near-continuous
human disturbance.
Of 105 cases of disturbance observed along the Northern
Beaches by day, most (24.8%) were caused by birds of prey:
Brahminy kite (Haliastur indus), whistling kite (H. sphenurus),
black kite (Milvus migrans), white-bellied sea-eagle (Haliaaetus
leucogaster), spotted harrier (Circus assimilis), nankeen kestrel
(Falco cenchroides) and Australian hobby (Falco longipennis). Raptors used a concealed approach when attacking shorebird
roosts, flying towards them behind the cover of dunes, cliffs
or trees. Attacks were abandoned if a shorebird flock became
airborne before any birds could be taken from the ground.
Roosting shorebirds were wary on the Northern Beaches and
often (21.9% of cases) took off in response to false alarms,
such as ospreys (Pandion haliaeatus), Caspian terns (Sterna caspia) or silver gulls (Larus novaehollandiae) flying low over roosts.
Ospreys were never seen attacking shorebirds and were generally ignored by them, so instances in which they flushed
waders were treated as false alarms. Many disturbances
(20.9%) were caused by humans, their dogs or their vehicles.
This measure probably underestimated the effect of human
disturbance, for unlike birds of prey, humans often remained
on beaches for some time after disturbing shorebirds, potentially preventing them from resettling. In 32.6% of cases we
could not identify the cause of disturbance.
3.3.
Disturbance costs
Total flight costs during a high tide for different roost sites
were plotted against the time spent in alarm flights. Results
for great knot from Fall Point (Fig. 2) were conceptually similar
to those for red knots, and for both species at other feeding
sites of northern Roebuck Bay (not presented here). Heavy
birds at departure mass incurred higher flight costs than lean
A
100
Bush Point
80
Salt Pans
60
Cable Beach
Open Mangrove
40
Northern Beaches
total flight cost (kJ)
small adjacent sea-stacks; only a small proportion of the
knots present could fit onto these sites, so their habitat
attributes were not included in the roost choice models.
Roosts on mudbanks on the intertidal flats of Roebuck Bay
were frequently used during neaps, but were submerged
and never used by shorebirds on tides >6 m. At night, knots
avoided sites that had nearby tall cover or had a dark background colour, one or both of these considerations making
them avoid roosts in mangrove clearings, Town Beach and
the Northern Beaches. As a result, distances flown from feeding areas to roosts were significantly greater at night than by
day, on both non-neaps (at night 6.69 ± 4.61 km, n = 655; by
day 1.72 km ± 1.59, n = 734, z = 26.313, Dunn–Sidak adjusted
P < 0.01) and on neaps (at night 2.66 ± 3.46 km, n = 136; by
day 1.89 km ± 2.87, n = 175, z = 2.095, Dunn–Sidak adjusted
P < 0.05).
Microclimate was similar at all sites at night. By day when
exposed to direct solar radiation, shorebirds were at risk of
heat stress, and only used roost sites with wet substrates or
shallow water, where counter-current exchange mechanisms
could be used to lower body temperature (Battley et al., 2003).
Suitably cool microclimates could be found along the wavewashed sand of beaches in all tide conditions by day. However, Cable Beach is next to a tourist resort and is often
unsuitable by day because of continuous human disturbance;
the Northern Beaches became unsuitable on the highest tides,
when the water-edge was too close to tall cover. In such tide
conditions, however, roosting options became available in
habitats that were otherwise too hot. Spring tides extended
far into the mangroves to form shallow lakes within some
large mangrove clearings. King tides flooded these clearings
so deeply that they became unsuitable for shorebirds, but in
these conditions the tide extended completely through the
mangroves to flood extensive lakes on the claypan systems
beyond. The claypans and mangrove clearings are also suitable for shorebirds when flooded by heavy rain.
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
20
0
B
200
Bush Point
Salt Pans
Open Mangroves,
Cable Beach
160
120
Northern Beaches
80
40
0
0
10
20
30
40
50
time in alarm flights (min)
Fig. 2 – Flight costs (kJ) per high tide of lean great knots
flying to different roosts from a feeding area at Fall Point,
assuming equal costs s1 for commuting and alarm flights
(Panel A) or that alarm flights are 3.58 times more costly
(Panel B). Grey-shaded areas indicate variation in flight costs
related to variation in body mass at Bush Point and the
Northern Beaches (upper boundary = costs for birds at
departure mass). Observed levels of disturbance at each
roost are indicated by black dots. Dotted lines indicate the
level of disturbance at the Northern Beaches above which
flying to Bush Point becomes a more economical option.
B I O L O G I C A L C O N S E RVAT I O N
birds, but the difference was relatively small, considerably
lower than the difference in costs between roosting at the
closest potential roost site or the most distant (Fig. 2). If short
alarm flights were assumed to be no more costly per time unit
than commuting flights, the Northern Beaches turned out to
be the most economical roost, provided the time spent in
alarm flights per high tide did not exceed 50 minutes
(Fig. 2A). However, the allometric equation of Nudds and Bryant (2000) predicts that costs of short flights in lean great knot
will be 3.58 times those of commuting flights, and following
this assumption, Bush Point (when undisturbed) turns out
to be a more economical roosting option than the Northern
Beaches if disturbance levels at the latter exceed 15.79 minutes (Fig. 2B). On average 30.17 ± 6.63 minutes (n = 233 scans)
were spent in alarm flights per high tide at the Northern Beaches, making that site a more expensive roost option than an
undisturbed Bush Point if short flights were 2.18 or more
times more costly than steady-state flight; this threshold factor was 1.84 for red knots at the same feeding site.
231
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
The relative amounts of energy allocated to different
activities at current levels of disturbance over a complete tidal
cycle did not appear to differ greatly between species or between feeding sites within northern Roebuck Bay (Table 5).
Foraging and digestion consumed more energy than other
activities. However, the additional costs of roosting were also
considerable. The combined costs of flying to roosts, and disturbance flights at roosts, ranged from 17.3% to 25.4% of the
total energy expenditure of great knot at different feeding
sites in northern Roebuck Bay (Table 5), and from 19.4% to
28.7% of the expenditure of the smaller red knot. In both species the cost of roost flights exceeded the amount of energy
expended when sleeping or when at active rest (i.e. awake,
but carrying out minimal activities such as vigilance or preening), although much more time was invested in these
activities.
Estimates of total energy expenditure during a complete
high tidal cycle increased with body mass. Energetic costs of
great knots at departure mass (of c. 240 g) were almost twice
Table 5 – Energy budgets of great knots (white background) and red knots (shaded grey) from four different feeding sites
(Fig. 1): (1) Fall Point; (2) Dampier Flats; (3) Town Beach; (4) Crab Creek Flats
Site 2
Site 3
Site 4
Site 1
Site 2
Site 3
Site 4
10.3%
11.6%
35.7%
22.6%
5.2%
14.6%
19.8%
8.7%
11.8%
33.2%
21.0%
6.6%
18.7%
25.4%
8.6%
12.4%
33.5%
21.2%
4.5%
19.7%
24.2%
10.7%
12.0%
36.8%
23.3%
2.3%
15.0%
17.3%
9.9%
10.6%
34.9%
22.1%
6.8%
15.8%
22.6%
8.2%
10.7%
32.1%
20.3%
8.5%
20.2%
28.7%
8.2%
11.3%
32.7%
20.7%
5.8%
20.3%
27.1%
10.4%
11.1%
32.7%
22.9%
2.9%
16.4%
19.4%
Average daily energy budget
Expenditure (kJ day1)
Expenditure/BMR
Daily requirement for pre-migratory mass gain (kJ day1)
336.2
4.53
386.2
362.3
4.88
412.3
358.0
4.83
408.0
326.7
4.40
376.7
230.4
4.36
271.3
250.6
4.75
291.6
246.2
4.66
287.2
221.8
4.20
262.7
Required intake rate to balance expenditure and fuelling
Intake (mg AFDM s1)
0.58
0.62
0.61
0.56
0.40
0.43
0.42
0.38
Relative cost of activity
Sleeping
Active rest
Foraging
Digesting
Commuting
Alarm flights
Total roost flights
expenditure per tide cycle (kJ)
1.1
10000
1.0
0.9
8000
0.8
0.7
6000
0.6
0.5
4000
0.4
0
10
20
30
40
requuired intake rate (mg AFDM s-1)
Site 1
50
time spent in alarm flights at Northern Beaches
(minutes)
Fig. 3 – Energy expenditure (solid lines) and extra requirement for mass gain (dashed lines) of 1.1 g day1 in great knot from
Fall Point over a full tidal cycle, plotted against the average duration of disturbance per high tide when roosting on the
northern beaches. Models for a lean great knot (147.5 g) are shown in black, for a fat great knot (240 g) in grey. The vertical line
indicates the disturbance levels found at the Northern Beaches in this study.
232
B I O L O G I C A L C O N S E RVAT I O N
as high as those at the usual non-breeding mass of 147.5 g
(Fig. 3). Costs were still higher in periods of pre-migratory
mass gain (Fig. 3), assuming mass-gain rates of 1.1 g day1
in great knots (linearly scaled up from red knot estimate of
0.9 g day1 at Roebuck Bay, Piersma et al., 2005). Energy
expenditure per tidal cycle was also sensitive to the amount
of disturbance on the Northern Beaches, although this roost
was only used on 25.9% of high tides. For example, the halfhour of alarm flight per high tide observed at the Northern
Beaches consumes almost as much energy per day as does
undertake pre-migratory mass gain at a typical rate (Fig. 3).
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
or otherwise makes them perceive night-roosts to be too dangerous for sleeping.
At Roebuck Bay the lack of vehicle access to the remote
saltpans should protect night roosts in this habitat for the
foreseeable future. Cable Beach is potentially more sensitive,
being close to the town of Broome; the roost there has serendipitously been protected from intrusion or illumination at
night because the dunes behind it are part of the Minyirr
Coastal Park, maintained for its cultural importance to
Aboriginal people.
4.2.
4.
Discussion
4.1.
Roosting options at night
At night on non-neap tides birds were prepared to pay a high
commuting price to roost in ideal conditions, most flying to
Cable Beach or the saltpans. Both sites were considerably
more distant than the roosts used on corresponding daytime
high tides. Use of different roost sites by day and night appears to be common in coastal shorebirds (Hockey, 1985; Handel and Gill, 1992; Smit and Visser, 1993; Sitters et al., 2001),
though it is by no means universal (Warnock and Takekawa,
1996; Van Gils and Piersma, 1999; Leyrer et al., 2006).
The roost choice models correctly predicted the observed
preferences for Cable Beach and the saltpans on night-time
neap high tides because the sites had pale backgrounds and
were distant from tall cover (the same applied to Bush Point,
but this site was rejected by the models as it was considerably
further away). Both attributes would increase the ease of
detecting approaching predators. In addition Cable Beach
and the saltpans happened to have the lowest levels of disturbance of the night-time roost sites (Table 3), suggesting they
were particularly ‘‘safe’’ roosts.
Although this reasoning is plausible, it is not entirely consistent with field observations. Shorebirds at Cable Beach at
night spent 87% of the high tide period asleep, and did not appear vigilant enough to detect predators; human observers
could walk to within 10 m of them as they slept, provided that
they moved quietly without using torchlight (pers. obs.). In
addition, Cable Beach is not free of predators; barking owls
(Ninox connivens) and house cats (Felis catus) have been observed hunting shorebirds there at night (pers. obs.).
Sleeping is the most energy-efficient activity possible for
shorebirds (Piersma et al., 2003a) and probably a physiological
necessity (Rattenborg et al., 1999); recent studies indicate that
birds are most predisposed to sleep in darkness (Rattenborg
et al., 2005). If there is a physiological requirement to spend
much of the night asleep, shorebirds may therefore select
night-time roosts perceived to have low levels of ‘‘danger’’
(i.e. the inherent probability of becoming a prey item if no
anti-predator measures are taken, Lank and Ydenburg,
2003). This consideration has received little consideration in
the disturbance literature (e.g. Davidson and Rothwell,
1993), but may be critical in urban shorebird habitats. Our repeated field experience at Roebuck Bay is that shorebirds
avoid roosting at sites where they are exposed to artificial
lighting such as streetlights or traffic. Possibly such lighting
makes roosting shorebirds too easily detected by predators,
Roosting options by day
Shorebirds at Roebuck Bay are more tolerant of disturbance by
day than at night, and on daytime high tides the most commonly used roosts, Northern and Town Beaches, were also
among the most heavily disturbed. Much of this disturbance
is natural, caused by birds of prey. However, it is now augmented by human activity, and the combined disturbance effects could reach the point at which the roosts become
unsuitable. This point may not be far away, given that alternative roosts in mangrove clearings and saltpans are preferred
when they become suitable on spring tides, or if flooded by
rains. In 2003, unseasonal rainfalls in May flooded large
salt-scolds on Roebuck Plains (Fig. 1) and before they dried
out in August, they were used in preference to the Northern
Beaches in all tide conditions.
Despite the high levels of disturbance at the Northern Beaches, they were the preferred roost on daytime high tides of
intermediate height (6.0–8.2 m). Our models indicate that this
is because knots roost on wet substrates with a relatively cool
microclimate; on tides of intermediate height the only alternative roosts for knots using feeding areas in the North of
Roebuck Bay are Cable Beach (frequently unsuitable due to
near-continuous human disturbance by day) and Bush Point
(about 25 km away). The combined commuting and alarm
flight costs of roosting on the frequently-used Northern Beaches exceed the costs of commuting to roost at the undisturbed Bush Point. Surprisingly though, Bush Point was not
used by day by any radio-tracked birds from feeding grounds
in northern Roebuck Bay (Rogers et al., in press). We suspect
this is because an uninterrupted flight of about 25 km in the
middle of the day could cause heat stress problems. Captive
studies indicate that the water efflux rate of flying knots increases rapidly with temperature, starting to exceed water influx rates somewhere between 15 and 23 C (Kvist, 2001).
Evidence that this critical water efflux rate is readily exceeded
in the tropical conditions of Roebuck Bay is provided by observations of panting in great and red knots; this heat loss
behaviour occurs regularly for a minute or so after short
flights (Battley et al., 2003). In cool climates where the costs
of flight are offset by the thermoregulatory advantages of
obtaining metabolic heat through locomotion (Bruinzeel and
Piersma, 1998), shorebirds can probably undertake longer
flights at high tide, an extreme example being a few sites
where intertidal shorebirds will spend an entire high tide on
the wing (Dekker, 1998; Hötker, 2000).
On present knowledge it is not possible to predict how
high disturbance levels can get on the Northern Beaches of
Roebuck Bay before shorebirds are forced to roost elsewhere
B I O L O G I C A L C O N S E RVAT I O N
in all tide conditions. The present abundance of shorebirds
there suggests that they can cope with the current levels of
disturbance. In future management of the site, it would be
prudent to ensure that disturbance levels do not increase
further.
4.3.
Energetic consequences of Roost choice
Our attempt to assess the energetic costs of roosting in Roebuck Bay is the first to use effective roost choice models to
predict local movements throughout a tidal cycle, taking into
account that shorebirds roost in different places according to
tide height and whether it is day or night. The overall energy
expenditure of knots in Roebuck Bay over a tidal cycle was
estimated to be 4.2–4.9 times as high as basal metabolism.
This is a high level of sustained expenditure, approaching
the inferred ‘metabolic ceiling’ of 4–5 times Basal Metabolic
Rate that was once considered to be found only in hard-working parent birds and growing animals (Weiner, 1992). However, high levels of energy expenditure appear to be typical
of shorebirds (Piersma, 2002; Piersma et al., 2003b). Our estimate is similar to the only direct measurements available of
field metabolic costs of non-breeding shorebirds (sanderling
Calidris alba), which ranged from 2.1 to 4.2 times Basal Metabolic Rate according to non-breeding area (Castro et al.,
1992). Field metabolic costs of shorebirds are higher in colder
climates (Castro et al., 1992; Wiersma and Piersma, 1994), and
it has been suggested that an advantage of migrating to warm
non-breeding grounds is the energetic saving of spending several months in sites where insulation costs are low (Wiersma
and Piersma, 1994). The estimates of energy costs in Roebuck
Bay suggest that the tropics are not necessarily ‘‘cheaper’’
non-breeding sites when the costs of activity (including roost
movements) are also considered.
The combined costs of flying to roosts, and at roosts because of disturbance, ranged from 17.3% to 28.7% of the total
energy budget of red and great knots in Roebuck Bay, a level of
expenditure that does not appear to be unusual. Commuting
flights accounted for 2.3–8.5% of the total tidal energy expenditure. In studies of red knot elsewhere, estimates of costs of
routinely made roost-flights (as a proportion of daily expenditure) were of similar scale: 12.2% at the Dee Estuary (Mitchell
et al., 1988) and 5.6% in the Dutch Wadden Sea (Piersma et al.,
1993; Rehfisch et al., 1996). The distances between feeding
sites and roosts in Roebuck Bay are also consistent with those
observed in previous studies, which range from 2.2 km in
western sandpipers Calidris mauri in San Francisco Bay (Warnock and Takekawa, 1996), to about 20 km or more for red
knots at estuaries in western Europe (Mitchell et al., 1988;
Van Gils et al., 2006). Comparison of disturbance levels with
other shorebird studies is difficult because different workers
have used different indices of disturbance. Disturbance levels
at the Northern Beaches were high, but the observed frequency of 3.36 alarm flights per hour is not unique. Similar
frequencies of disturbance incidents have been recorded on
the Dee Estuary (Kirby et al., 1993) and Tagus Estuary (Rosa
et al., 2006).
Energy expenditure over a tidal cycle was sensitive to the
amount of disturbance. For example, an average 30-min increase per tide in the amount of time spent in alarm flights
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
233
at the Northern Beaches (a site used on only 25% of high tides)
would increase the total energy expenditure by 13.3% in a
lean great knot (Fig. 3). Shorebirds may be able to compensate
for these costs to some extent by extending their food intake
but the extent to which they can do this will be finite; it will be
limited ultimately by digestive capacity or the prey available
at a site (Van Gils et al., 2005). Energy expenditure and required intake rates over a tidal cycle increase with body mass
(Fig. 3), and would therefore be expected to be highest in the
final stages of pre-migratory mass gain. The higher energy demands of heavier birds might be helpful in identifying situations where shorebirds are experiencing difficulty in meeting
the energetic costs of roosting, as such individuals may be obliged to select roosts with lower energy costs but presumably
higher risk levels. Such scenarios appear to have been observed by Handel and Gill (1992) and by Van Gils and Piersma
(1999), who described changes in roosting behaviour of dunlin
(Calidris alpina) and red knots, respectively, as they approached departure mass.
In one of the few detailed investigations of roost choice in
intertidal shorebirds, Rehfisch et al. (2003) remarked that ‘‘. . .
any change in roosting conditions is likely to be less detrimental than loss of feeding areas’’. While we agree that feeding areas are vital, we do not agree that loss of roosts should
not be considered a separate concept; feeding areas are only
of use to shorebirds if they are associated with acceptable
roosts (Dias et al., 2006). If the energetic costs of roosting
should increase expenditure to the point where shorebirds
cannot meet their energy requirements for maintenance,
moult and pre-migratory fuelling, then diminished survival
(Durell et al., 2005) and a loss of feeding areas are inevitable.
Our models demonstrate that within the scale of a naturally
occurring shorebird site, a relatively small increase in disturbance levels can result in a substantial increase in energy
expenditure. The capacity of shorebirds to compensate for
such increases will vary according to the feeding and roosting
options available at a site, but it is very likely that circumstances can develop where roost costs could drive the energy
budget into deficit. The adequacy of roost habitats should
therefore be considered carefully in management of coastal
shorebird sites.
Acknowledgements
Funding essential to our research was provided by the National Geographic Society (Washington, DC), a PIONIER grant
to TP from the Netherlands Organisation for Scientific Research (NWO) and a postgraduate scholarship to DIR from
Charles Sturt University. Vital fieldwork support came from
Broome Bird Observatory and the Western Australian Department of Conservation and Land Management (CALM). For
their help in unravelling the roost choice story in Roebuck
Bay, we are most grateful to P. Battley, K. Rogers, J. Van Gils,
A. Boyle, G. Pearson, P. De Goeij, J. Van de Kam, A. Dekinga,
E. Gilbert, A. Koolhaas, M. Russell, H. Sitters, B. Spaans, A.
Dunn, J. Sparrow and J. Schoenjahn. We thank J. Van Gils, M.
Rehfisch, K. Rogers, I. Taylor and an anonymous referee for
comments on previous drafts of the paper and D. Visser for
preparing the figures. This research was approved by the
234
B I O L O G I C A L C O N S E RVAT I O N
Ethics sub-Committee for Experimentation on Animals, Griffith University, and carried out under appropriate permits
from the Conservation and Land Management Agency, Western Australia.
R E F E R E N C E S
Battley, P.F., Dekinga, A., Dietz, M.W., Piersma, T., Tang, S.,
Hulsman, K., 2001. Basal metabolic rate declines during
long-distance migratory flight in great knots. Condor 103,
838–845.
Battley, P.F., Rogers, D.I., Piersma, T., Koolhaas, A., 2003.
Behavioural evidence for heat-load problems in great knots in
tropical Australia fuelling for long-distance flight. Emu 103,
97–104.
Battley, P.F., Piersma, T., Rogers, D.I., Dekinga, A., Spaans, B., Van
Gils, J.A., 2004. Do body condition and plumage during fuelling
predict northwards departure dates of great knots Calidris
tenuirostris from North-west Australia? Ibis 146, 46–80.
Bruinzeel, L.W., Piersma, T., 1998. Cost reduction in the cold: heat
generated by terrestrial locomotion partly substitutes for
thermoregulation costs in knot Calidris canutus. Ibis 140,
323–328.
Castro, G., Myers, J.P., Ricklefs, R.E., 1992. Ecology and
energetics of sanderlings migrating to four latitudes.
Ecology 73, 833–844.
Davidson, N.C., Rothwell, P., (Eds.), 1993. Disturbance to waterfowl
on estuaries. Wader Study Group Bulletin 68, special issue.
Dekker, D., 1998. Over-ocean flocking by dunlins, Calidris alpina,
and the effect of raptor predation at Boundary Bay, British
Columbia. Canadian Field Naturalist 112, 694–697.
Dias, M.P., Granadeiro, J.P., Lecoq, M., Santos, C.D., Palmeirim, J.M.,
2006. Distance to high-tide roosts constrains the use of
foraging areas by dunlins: Implications for the management of
estuarine wetlands. Biological Conservation 131, 446–452.
Durell, S.E.A.Le.V. dit, Stillman, R.A., Triplet, P., Aulert, C., Biot,
D.O. dit, Bouchet, A., Duhamyl, S., Mayot, S., Goss-Custard, J.D.,
2005. Modelling the efficacy of proposed mitigation areas for
shorebirds: a case study on the Seine Estuary, France.
Biological Conservation 123, 67–77.
Giese, M., 1998. Guidelines for people approaching breeding
groups of Adélie penguins (Pygoscelis adeliae). Polar Record 34,
287–292.
Hambly, C., Pinshow, B., Wiersma, P., Verhulst, S., Piertney, S.B.,
Harper, E.J., Speakman, J.R., 2004. Comparison of the cost of
short flights in a nectarivorous and a non-nectarivorous bird.
Journal of Experimental Biology 207, 3959–3968.
Handel, C.M., Gill Jr., R.E., 1992. Roosting behaviour of
pre-migratory dunlins (Calidris alpina). Auk 109, 57–72.
Higgins, P.J., Davies, S.J.J.F. (Eds.), 1996. Handbook of Australian,
New Zealand and Antarctic Birds. snipe to pigeons, vol. 3.
Oxford University Press, Melbourne.
Hockey, P.A.R., 1985. Observations on the communal roosting of
African black oystercatchers. Ostrich 56, 52–57.
Hötker, H., 2000. When do dunlins spend high tide in flight?
Waterbirds 23, 482–485.
Kirby, J., Clee, C., Seager, V., 1993. Impact and extent of
recreational disturbance to wader roosts on the Dee Estuary:
some preliminary results. Wader Study Group Bulletin 68,
53–58.
Kvist, A., 2001. Water and heat loss of red knots flying at different
ambient temperatures. In: Kvist, A. (Eds.), Fuel and fly:
adaptations to endurance exercise in migrating birds. PhD
Thesis, Lund University.
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
Kvist, A., Lindström, Å., Green, M., Piersma, T., Visser, G.H., 2001.
Carrying large fuel loads during sustained bird flight is
cheaper than expected. Nature 413, 730–732.
Lank, D.B., Ydenburg, R.C., 2003. Death and danger at migratory
stopovers: problems with ‘‘predation risk. Journal of Avian
Biology 34, 225–228.
Leyrer, J., Spaans, B., Camara, M., Piersma, T., 2006. Small
home range sizes and high site fidelity in red knots (Calidris
c. canutus) wintering on the Banc d’ Arguin, Mauritania.
Journal of Ornithology 37, 238–244. doi:10.1007/s10336-0050030-8.
Luı́s, A., Goss-Custard, J.D., Moreira, M.H., 2001. A method for
assessing the quality of roosts used by waders during high
tide. Wader Study Group Bulletin 96, 71–74.
Mitchell, J.R., Moser, M.E., Kirby, J.S., 1988. Declines in midwinter
counts of waders roosting on the Dee estuary. Bird Study 35,
191–198.
Newton, I., 1998. Population limitation in birds. Academic Press,
London.
Nudds, R.L., Bryant, D.M., 2000. The energetic costs of short flights
in birds. Journal of Experimental Biology 203, 1561–1572.
O’Connor, R.J., Brown, R.A., 1977. Prey depletion and foraging
strategies in the oystercatcher Haematopus ostralegus.
Oecologia 27, 75–92.
Piersma, T., 2002. Energetic bottlenecks and other design
constraints in avian annual cycles. Integrative and
Comparative Biology 42, 51–67.
Piersma, T., Cadée, N., Daan, S., 1995. Seasonality in basal
metabolic rate and thermal conductance in a long-distance
migrant shorebird, the knot (Calidris canutus). Journal of
Comparative Physiology B 165, 37–45.
Piersma, T., Dekinga, A., Van Gils, J.A., Achterkamp, B., Visser,
G.H., 2003a. Cost-benefit analysis of mollusc eating in a
shorebird. 1. Foraging and processing costs estimated by the
doubly labelled water method. Journal of Experimental Biology
206, 3361–3368. doi:10.1242/jeb.00545.
Piersma, T., Hoekstra, R., Dekinga, A., Koolhaas, A., Wolf, P.,
Battley, P., Wiersma, P., 1993. Scale and intensity of intertidal
habitat use by knots Calidris canutus in the western Wadden
Sea in relation to food, friends and foes. Netherlands Journal
of Sea Research 31, 331–357.
Piersma, T., Lindström, Å., Drent, R., Tulp, I., Jukema, J., Morrison,
R.I G., Reneerkens, J., Schekkerman, H., Visser, G.H., 2003b.
High daily energy expenditure of incubating shorebirds on
High Arctic tundra: a circumpolar study. Functional Ecology
17, 356–362.
Piersma, T., Rogers, D.I., González, P.M., Zwarts, L., Niles, L.J., de
Lima Serrano do Nascimento, I., Minton, C.D.T., Baker, A.J.,
2005. Fuel storage rates in red knots worldwide: facing the
severest ecological constraint in tropical intertidal conditions?
In: Greenberg, R., Marra, P.P. (Eds.), Birds of two worlds: the
ecology and evolution of migratory birds. Johns Hopkins
University Press, Baltimore, pp. 262–274.
Rattenborg, N.C., Lima, S.L., Amlaner, C.J., 1999. Half-awake to the
risk of predation. Nature 397, 397–398.
Rattenborg, N.C., Obermeyer, W.H., Vacha, E., Benca, R.M., 2005.
Acute effects of light and darkness on sleep in the pigeon
(Columba livia). Physiology and Behaviour 84, 635–640.
Rehfisch, M.M., Clark, N.A., Langston, R.H.W., Greenwood, J.J.D.,
1996. A guide to the provision of refuges for waders: an
analysis of 30 years of ringing data from the Wash, England.
Journal of Applied Ecology 33, 673–687.
Rehfisch, M.M., Insley, H., Swann, B., 2003. Fidelity of
overwintering shorebirds to roosts on the Moray Basin,
Scotland: Implications for predicting impacts of habitat loss.
Ardea 91, 53–70.
Rogers, D.I., 1999. What determines shorebird feeding distribution
in Roebuck Bay? In: Pepping, M., Piersma, T., Pearson, G.,
B I O L O G I C A L C O N S E RVAT I O N
Lavaleye, M., (Eds.), Intertidal sediments and benthic animals
of Roebuck Bay, Western Australia. NIOZ-report 1999–3, pp
145–174. Netherlands Institute for Sea Research (NIOZ),
Texel.
Rogers, D.I., 2003. High-tide roost choice by coastal waders. Wader
Study Group Bulletin 100, 73–79.
Rogers, D.I., Battley, P.F., Piersma, T., Van Gils, J.A., Rogers, K.G., in
press. High tide habitat choice: insights from modelling roost
selection by shorebirds around a tropical bay. Animal
Behaviour.
Rogers, D.I., Piersma, T., Lavaleye, M., Pearson, G.B., De Goeij, P.,
2003. Life along Land’s Edge: Wildlife on the shores of Roebuck
Bay, Broome. Western Australian Department of Conservation
and Land Management, Kensington WA.
Rosa, S., Encarnação, A.L., Granadeiro, J.P., Palmeirim, J.M., 2006.
High water roost selection by waders: maximising feeding
opportunities or avoiding predation? Ibis 148, 88–97.
Sitters, H., González, P.M., Piersma, T., Baker, A.J., Price, D.J., 2001.
Day and night feeding habitat of red knot in Patagonia:
profitability versus safety? Journal of Field Ornithology 72,
86–95.
Smit, C., Visser, G.M., 1993. Effects of disturbance on
shorebirds: a summary of existing knowledge from the
Dutch Wadden Sea and Delta area. Wader Study Group
Bulletin 68, 6–19.
Triplet, P., Stillman, R.A., Goss-Custard, J.D., 1999. Prey abundance
and the strength of interference in a foraging shorebird.
Journal of Animal Ecology 68, 254–268.
Tulp, I., De Goeij, P., 1994. Evaluating wader habitats in Roebuck
Bay (North-western Australia) as a springboard for
northbound migration in waders, with a focus on Great knots.
Emu 94, 78–95.
1 3 3 ( 2 0 0 6 ) 2 2 5 –2 3 5
235
Van Gils, J.A., Dekinga, A., Spaans, B., Vahl, W.K., Piersma, T., 2005.
Digestive bottleneck affects foraging decisions in red knots
(Calidris canutus). II Patch choice and length of working day.
Journal of Animal Ecology 74, 120–130.
Van Gils, J., Piersma, T., 1999. Day- and nighttime movements of
radiomarked knots, Calidris canutus, staging in the western
Wadden Sea in July-August 1995. Wader Study Group Bulletin
89, 36–44.
Van Gils, J.A., Piersma, T., 2004. Digestively constrained predators
evade the cost of interference competition. Journal of Animal
Ecology 73, 386–398.
Van Gils, J.A., Schenk, I.W., Bos, O., Piersma, T., 2003. Incompletely
informed shorebirds that face a digestive constraint maximize
net energy gain when exploiting patches. American Naturalist
161, 777–793.
Van Gils, J.A., Spaans, B., Dekinga, A., Piersma, T., 2006. Foraging
in a tidally structured environment by red knots (Calidris
canutus): ideal, but not free. Ecology 131, 1189–1202.
Warnock, S.E., Takekawa, J.Y., 1996. Wintering site fidelity and
movement pattens of western sandpipers Calidris mauri in the
San Francisco Bay estuary. Ibis 138, 160–167.
Weiner, J., 1992. Physiological limits to sustainable energy budgets
in birds and mammals: ecological implications. Trends in
Ecology and Evolution 7, 384–388.
Wiersma, P., Piersma, T., 1994. Effects of microhabitat, flocking,
climate and migratory goal on energy expenditure in the
annual cycle of red knots. Condor 96, 257–279.
Zharikov, Y., Skilleter, G.A., 2003. Depletion of benthic invertebrates
by bar-tailed godwits Limosa lapponica in a subtropical estuary.
Marine Ecology Progress Series 254, 151–160.
Zwarts, L., 1988. Numbers and distribution of coastal waders in
Guinea-Bissau. Ardea 76, 42–55.
Chris Hassell
P O Box 3089 ~ Broome, WA. 6725 ~ Australia
Work Phone (08) 9192 8585
E-mail [email protected]
Dear Shire
I am writing to you to suggest strongly that ‘Area E’ is an unsuitable location for the location
of the new tip.
I will address some points from the Talis document below but the most important issue with
‘Area E’ would be that it will bring huge numbers of birds of prey (BOPs)(mostly Black Kikes
Milvus migrans and Whistling Kites Haliastur sphenurus) close to the internationally
protected migratory shorebird roosts on the northern shores of Roebuck Bay.
Please take time to peruse the attached documents. BOPs are the major source of
disturbance to shorebird roosts in Roebuck Bay. Small amounts of disturbance from Whitebellied Sea-Eagle Haliaeetus leucogaster and Brahminy Kite Haliastur indus are a natural
issue but constant disturbance from other BOPs brought in to the area by a tip facility are
not.
It is unacceptable to relocate the tip 3-5km from these internationally important and
protected species. Not to mention the detriment to the tourism opportunities that the bird
watching at Roebuck Bay provides.
The environmental approvals for this site will be onerous.
Roebuck Bay is a Ramsar site, not a RAMSAR site as the document reads a number of times.
It gives me little faith in the consultant when such a simple thing is incorrect.
The document makes a number of statements that I will respond to directly below.
However, it must be done in a manner that minimises the impacts on the local and global
environment.
This will not be the case. Over 1,000 BOPs can be found at the current tip and there is
nothing in the new plan to suggest this will change. No mention of covering the tip as is
done at other facilities in Australia.
The initial phase of the process involved defining Site Selection Criteria based on
environmental, social and planning factors
I had a meeting with Leah Pearson, Kandy Curran and a Sydney-based consultant in April
2011 and mentioned the very same points I am mentioning again here. So they don’t seem
to have been considered very carefully?
Site Selection Criteria shown in Table 1 were developed prior to any site investigations. They
consider a range of environmental, social and planning factors
See above.
Preferably a distance of 9km to aerodrome (Talis normally adopts this international
standard of 9km)
From the maps supplied it would appear that the new tip will be only about 5km from the
airport when it is relocated. The huge numbers of BOP”s plus gulls, corellas, crows and ibis
that will be present at the new tip is not exaggerated. Anyone who has visited the current
tip will attest to this. Those reading this letter are no doubt well aware of it themselves.
Minimum separation distance of 100m from Surface Water bodies.
During wet season flooding Area E will be very close to the Dampier Creek floodplain
(probably more than 100M) and during big rain events and huge tides the possibility of
contamination of Dampier Creek and the Ramsar-listed Roebuck Bay will be very real.
Preferably located less than 2km from a sealed road catering for heavy vehicle movements.
From the maps supplied it appears the tip will be more than 5km from the sealed road.
Preferably site not located within the following:

RAMSAR Wetland;
A tip at area E will probably bring about 1,000 BOPs close to the internationally protected
Ramsar wetland of Roebuck Bay. This will lead to increased disturbance of protected species
(JAMBA, CAMBA, ROKAMBA).
I would be very happy to meet with any Shire or Talis staff to discuss this letter.
Chris Hassell
Global Flyway Network
Australasian Wader Studies Group.
Chris Hassell
P O Box 3089 ~ Broome, WA. 6725 ~ Australia
Work Phone (08) 9192 8585
E-mail [email protected]
18 November 2014
Dear Shire
I am writing to you as a stakeholder in relation to the new tip facility.
I hope you do not find this impertinent. I was not invited to the stakeholders meeting but having
lived in Broome and been researching the migratory shorebirds of Roebuck Bay since March 1996 I
consider myself a stakeholder in this issue, particularly in relation to Area E.
I have had various meetings and dealing with the shire over the 18+ years I have been here in
relation to the bay including a meeting in April 2011 with Leah Pearson and a Sydney-based
consultant on this very matter. I was surprised and disappointed that I was not invited to the
meeting.
My response is quite brief (see attached) but this is due to the unfair timeframe given to comment
in. I will be away with a team of 9 people as of Tuesday at Anna Plains/80 Mile Beach (counting
migratory shorebirds in a project supported by DPaW) and then counting for 2 days in Roebuck Bay
and tomorrow (Monday) I will be busy preparing for this fieldwork.
As it says in my attached letter I would be very happy to meet with any Shire or Talis staff to
discuss this matter.
Chris Hassell

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