Independant Study Contract N395

Transcription

ALCOA OF AUSTRALIA
No. 37
THREATENED FAUNA SPECIES
MANAGEMENT PLANS
FOR ALCOA’S BAUXITE MINING OPERATIONS
IN THE JARRAH FOREST
V. L. STOKES
M. A. NORMAN
June 2010
ISSN 1320-4807
TABLE OF CONTENTS
LIST OF FIGURES................................................................................................................. 2
INTRODUCTION ................................................................................................................... 3
1. WESTERN QUOLL (Dasyurus geoffroii) ......................................................................... 5
1.1 Conservation status ......................................................................................................... 5
1.2 Description and taxonomic relationships ........................................................................ 5
1.3 Species biology and ecology ........................................................................................... 6
1.4 Distribution and preferred and critical habitat ................................................................ 8
1.5 Key threats..................................................................................................................... 10
1.6 Management actions ...................................................................................................... 13
1.7 Recommendations ......................................................................................................... 17
2. QUOKKA (Setonix brachyurus)....................................................................................... 19
2.1 Conservation status ....................................................................................................... 19
2.2 Description and taxonomic relationships ...................................................................... 19
2.3 Species biology and ecology ......................................................................................... 20
2.4 Distribution and preferred and critical habitat .............................................................. 22
2.5 Key threats..................................................................................................................... 25
3. BAUDIN’S BLACK COCKATOO (Calyptorhynchus baudinii) and FOREST REDTAILED BLACK COCKATOO (Calyptorhynchus banksii naso) .................................... 34
3.2 Description and taxonomic relationships ...................................................................... 34
3.5 Key threats..................................................................................................................... 43
4. NOISY SCRUB-BIRD (Atrichornis clamosus) ............................................................... 50
4.2 Description and taxonomic relationships ..................................................................... 50
4.5 Key threats..................................................................................................................... 56
ii
5. PEREGRINE FALCON (Falco peregrinus) ................................................................... 63
5.5 Key threats..................................................................................................................... 69
6. CARPET PYTHON (Morelia spilota imbricata) ............................................................. 73
6.5 Key threats..................................................................................................................... 76
SUMMARY AND PRIORITY OF RECOMMENDED ACTIONS FOR
MANAGEMENT OF THREATENED FAUNA ................................................................ 81
REFERENCES ...................................................................................................................... 85
iii
LIST OF FIGURES
Fig. 1.
Alcoa of Australia’s mineral lease in south-western Western Australia and the operational
bauxite mine sites at Huntly and Willowdale. ................................................................... 4
Fig. 2.
The western quoll, distinguished from other Dasyurus species by having no spots on the
tail, five toes on the hind feet and granular foot pads (Groves 2005). .............................. 6
Fig. 3.
Chuditch occupy the jarrah forest and woodland zone and have scattered distribution
(black dots) in the wheatbelt zone of south-west Western Australia (adapted from Serena
et al. 1991). ...................................................................................................................... 10
Fig. 4.
A fauna habitat returned to post-mining rehabilitation, constructed from piles of logs,
rocks and soil. .................................................................................................................. 15
Fig. 5.
A female Quokka (Rottnest Island Authority 2007). ....................................................... 20
Fig. 6.
Distribution of the Quokka as of 2000. Stars indicate known occurrence while open
circles are possibly extinct populations. The filled area shows the area of occupancy
while the solid line shows the extent of occurrence. The 700 mm (dotted) and 1000 mm
(short dashed line) annual rainfall isohyets are shown (Hayward 2002). ....................... 23
Fig. 7.
Location of five known quokka populations at Chandler, Hadfield, Kesners, Rosella Road
and Victor Road in the northern jarrah forest (Hayward et al. 2004). ............................ 24
Fig. 8.
Baudin’s black cockatoo: male (left) and female (right) (Johnstone and Storr 1998)..... 36
Fig. 9.
Female Forest Red-tailed black cockatoo (photo by Tony Kirkby)................................. 37
Fig. 10.
Distribution map of Baudin’s cockatoo (Chapman and Massam 2005). ......................... 41
Fig. 11.
Distribution map of the three sub-species of Forest Red-tailed Black Cockatoo (modified
from Johnstone and Storr 1998). ..................................................................................... 42
Fig. 12.
The Noisy Scrub-bird (Atrichornis clamosus) (Chapman 2007). .................................... 51
Fig. 13.
Former (open boxes) and existing (closed boxes) distribution of the Noisy Scrub-bird
(Danks et al. 1996)........................................................................................................... 54
Fig. 14.
Adult Peregrine Falcon, Falco peregrinus (www.nationalgeographic.com.au) ............... 64
Fig. 15.
Distribution of the major types of nest site used by peregrine falcons prior to 1982: a)
Stick nests (n=55); b) Tree hollows (n=43); c) Cliff sites (n=234) (Olsen 1982). ......... 68
Fig. 16. Webcam footage of a breeding pair of peregrine falcon and their chick at a man-made nest
box at Alcoa Anglesea in Victoria................................................................................... 72
Fig. 17.
Morelia spilota (Groves 2005). ........................................................................................ 74
2
INTRODUCTION
Alcoa of Australia presently operates two bauxite mines at Huntly and Willowdale
within the northern jarrah (Eucalyptus marginata) forest of the Darling Range of
south-west Western Australia (Fig. 1). Most of the bauxite reserves lie in a 4200 km2
area within State forest to the south-east of Perth (Elliott et al. 2001). Approximately
600 ha of forest are cleared and rehabilitated annually. Bauxite pits range from
between 2 and 100 ha in size and form a mosaic of varying aged rehabilitation and
unmined forest across the landscape. Alcoa is committed to minimising the impacts of
mining on fauna and creating rehabilitated forest that maximises fauna return postmining.
In 2005, Alcoa developed an Environmental Improvement Plan (EIP) in conjunction
with members of the community, non-government organisations, universities, state
government representatives and environmental regulators. The EIP sets clear targets
and actions for improvement in all areas of Alcoa’s operations. One of the EIP
commitments is to minimise impacts on fauna species which inhabit areas
surrounding mining operations and to maximise recolonisation of fauna into areas
rehabilitated following mining. This includes managing rare and threatened species
that occur within Alcoa’s mining region.
The purpose of this document is to describe the threatened species that occur within
Alcoa’s mining lease and outline the broad management actions Alcoa has
implemented to minimise the impact of its operations on these species and fauna in
general. Ongoing research by Alcoa and its affiliated partners is described. Specific
actions are then recommended for managing each of the identified threatened species
within Alcoa’s mining lease. These species include:
Those
1950:
•
•
•
•
•
listed as ‘Threatened’ under Western Australia's Wildlife Conservation Act
Western Quoll, Dasyurus geoffroii
Quokka, Setonix brachyurus
Noisy Scrub-bird, Atrichornis clamosus
Baudin’s Black Cockatoo, Calyptorhynchus baudinii
Forest Red-tailed Black Cockatoo, Calyptorhynchus banksii naso
Those listed as ‘Specially Protected’ under Western Australia's Wildlife Conservation
Act 1950:
• Peregrine Falcon, Falco peregrines
• Carpet Python, Morelia spilota imbricata
3
Fig. 1. Alcoa of Australia’s mineral lease in south-western Western Australia and the
operational bauxite mine sites at Huntly and Willowdale.
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1. WESTERN QUOLL (Dasyurus geoffroii)
1.1 Conservation status
The western quoll (Dasyurus geoffroii) is given special protection under Western
Australia's Wildlife Conservation Act 1950. It is listed as "Declared Threatened
Fauna: Schedule 1 - Fauna that is rare or is likely to become extinct". The western
quoll is listed as vulnerable under the federal Environment Protection and
Biodiversity Conservation (EPBC) Act 1999. It has a ranking under World
Conservation Union criteria of “Vulnerable C1: population number of less than
10,000 individuals and an observed, estimated, inferred or suspected reduction of at
least 10% over the last 10 years or three generations” (last updated in 1994; IUCN
2007). Based on the ICUN’s criteria the western quoll could now be down-listed to
Lower Risk (Conservation Dependent - Johnson 1999; K. Morris unpublished data,
2000).
1.2 Description and taxonomic relationships
The western quoll (Dasyurus geoffroii Gould 1841), also commonly known as the
chuditch, is the largest carnivorous marsupial in Western Australia. There are five
other species in the genus Dasyurus: the Northern quoll (D. hallucatus) of the Pilbara,
Kimberley, Northern Territory and Queensland; the Eastern quoll (D. viverrinus) of
Tasmania; the Tiger quoll (D. maculates) of eastern Australia; and D. albopunctatus
and D. spartacus of Papua New Guinea (Serena et al. 1991). Genetically, the western
quoll is most closely related to D. spartacus in New Guinea (Firestone 1999). The
Noongar people from the south-west of Western Australia called the species ‘djutytch’ and the term ‘chuditch’ was derived by early settlers (Smith et al. 2004). Quolls
are related to marsupial mice (Antechinus spp.) and the Tasmanian devil (Smith et al.
2004).
The western quoll (herein referred to as chuditch) is reddish-brown to grey in colour
with distinctive white spots and a long tail with a black brush on the distal half (Fig.
2) (Van Dyck and Strahan 2008). They have large rounded ears, a pointed muzzle and
toes with rough fleshy pads that assist with climbing trees. The front paw has five toes
each with a long claw, while the back paw has a very small clawless first toe and four
larger toes with long claws. They have a non-hopping gait, sharp teeth and keen
senses of sight, hearing and smell (Serena et al. 1991). Females are smaller than
males, weighing 900 g on average compared to 1300 g for males (Anon 2007). Body
length averages 360 mm in males and 310 mm in females, while the tail length is 305
mm in males and 275 mm in females.
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Fig. 2. The western quoll, distinguished from other Dasyurus species by having no spots on
the tail, five toes on the hind feet and granular foot pads (Groves 2005).
1.3 Species biology and ecology
1.3.1 Lifespan, breeding and behaviour
The lifespan of chuditch in the wild is generally two to four years, although they can
live up to five years in captivity (Soderquist 1988; Serena et al. 1991). Both females
and males are sexually mature and able to breed in their first year. Chuditch are
seasonal breeders and mating commences in late April when females enter oestrous. A
female may mate with several different males for the duration of her oestrous
(approximately four to ten days) (Stead-Richardson et al. 2001). Gestation is between
17 – 18 days after which time females give birth to up to six young. Births occur
between May and September, and in the jarrah forest generally occur in June or July
(Soderquist and Serena 1990). At birth, young are blind, hairless, about 7 mm in
length and less than one gram in weight. They crawl into the rudimentary pouch and
attach to a teat, where they will remain for about 60 days before exiting the pouch to
live in the den in late August to early October (Serena et al. 1991). When first left in
the den, young weigh less than 15 g and are blind and poorly insulated by fur.
Juveniles begin exploring outside the den in October and November at the age of 17
weeks. They are out of the den for only short periods in the early evening, followed
by rest inside the den or near its mouth. The time spent foraging and the distance
travelled from the den rapidly increase in the initial three weeks of juvenile
exploration (Soderquist and Serena 2000). The juveniles explore and learn to hunt
6
without their mother and after 22 -24 weeks are fully weaned and spending most of
the night alone outside of the den. At this time juveniles may venture more than 500
m each night (Soderquist and Serena 2000).
Juvenile departure from the maternal home range may take over a week following the
initial separation from the mother. By 25 weeks, male juveniles have generally
covered long distances (>10 km), while most females settle in areas adjacent to or
share the maternal home range (Soderquist and Serena 2000). Sharing of home ranges
by relatives is apparently amicable, yet females will shift core home ranges to reduce
overlap with other females where possible. Home ranges of males overlap extensively
with those of both females and other males. Once settled in an area, chuditch are
unlikely to shift home ranges and transient animals are very rare (Serena and
Soderquist 1989). The home ranges are large; males have a home range of 15 km2
and females have a home range of 3-4 km2. Within these home ranges, there is a
smaller core area defined by den locations of 4 km2 for males and 0.9 km2 for females.
Core home ranges of females are largely distinct and are marked with scent, implying
active territoriality (Serena and Soderquist 1989).
Chuditch are solitary, nocturnal animals and sleep in dens during the day. They have
a short, sharp guttural call, which is an aggressive sound used to defend food
resources or when threatened by a predator (Serena 1987). Males are often injured
during the breeding season because of fighting over territories and mates. Wild
juveniles have been observed to wrestle, which potentially facilitates social cohesion
amongst the litter and may be practice for fighting techniques used in adult life to
defend territories and secure mates (Soderquist and Serena 2000). The population sex
ratio of males and females of juveniles and adults in the jarrah forest is roughly equal
(Orell and Morris 1994).
1.3.2 Diet
Chuditch are opportunistic, mainly carnivorous feeders and have a wide taxonomic
diversity of prey as well as a relatively wide range of prey size (Soderquist and Serena
1994). Although chuditch commonly eat vertebrates (small mammals, birds and
lizards), their diet is predominately large invertebrates. At Batalling forest,
invertebrate remains comprised 66% of scats and a similar result was found for
chuditch in the Dwellingup area (Morris and Orell 1994). Invertebrate prey includes
large centipedes, beetles, cockroaches and termites (Soderquist and Serena 1994). In
the jarrah forest, vertebrate prey includes medium-sized mammals (Southern Brown
Bandicoot: Isoodon obesulus and the European Rabbit: Oryctolagus cuniculus), small
mammals (Yellow-footed Antechinus: Antechinus flavipes, Brush-tailed Phascogale:
Phascogale tapoatafa and the House Mouse: Mus musculus) and birds (Splendid
Wren: Malurus splendens and the White-breasted Robin: Eopsaltria georgina). The
remains of the numbat were found in chuditch scats at Batalling forest, and failure of
7
attempts to re-establish a numbat population may partly result from chuditch being a
significant predator of this species (Morris and Orell 1994). Small fruits, flower parts
and the red pulp surrounding zamia (Macrozamia riedlei) seeds are also consumed
(Serena et al. 1991; Soderquist and Serena 1994). The diet of chuditch probably
varies significantly between different habitats (Soderquist and Serena 1994) and
potentially across seasons in response to resource availability. Food is limited during
the colder months between June and August (Orell and Morris 1994).
Chuditch primarily forage on the ground, digging into soil, searching through leaf
litter and probing crevices with the forepaws (Orell and Morris 1994). They are agile
with their forepaws, having been observed grabbing moths mid-air (Soderquist and
Serena 1994). They are also able to climb trees to obtain prey or escape from
predators, although Soderquist and Serena (1994) noted that chuditch are not adept
climbers and probably only obtain a limited amount of prey arboreally. Chuditch
rarely drink, generally obtaining sufficient fluid from their diet. They are able to eat
large amounts of food in short periods, for example 12% of their body weight in 15
minutes (Soderquist and Serena 1993). Chuditch are known to forage along roads and
to feed on carrion, making them vulnerable to road traffic.
1.4 Distribution and preferred and critical habitat
The chuditch formally occurred over approximately 70% of Australia and was one of
the most widespread Australian marsupials, present in every mainland state and
territory (Orell and Morris 1994). The geographical range of the chuditch contracted
dramatically following European settlement and they now occupy only 5% of their
former range, presently restricted to the south-west of Western Australia (Serena et al.
1991). The last specimens were collected in NSW in 1841, Victoria in 1857,
Queensland in 1907, and South Australia in 1931 (Orell & Morris 1994). They
disappeared from the central arid zone of Australia around the mid-1950’s (Finlayson
1961), are thought to have disappeared from the Swan Coastal Plain by the 1930’s and
had declined to 6,000 confined to the south-west of Western Australia by the 1970’s
(Fig. 3; Orell and Morris 1994). Chuditch now predominately occur in varying
densities in jarrah (Eucalyptus marginata) forest and there are only occasional records
in the drier woodlands and mallee shrublands of the wheatbelt and goldfields where it
persists in very low numbers (Fig. 3; Fletcher and Morris 2003). In 1994-1995, only
one chuditch was trapped in the wheatbelt, despite over 10,000 trap nights. Occasional
sightings and road kills indicate chuditch are still present in the wheatbelt and south
coast areas, but at very low densities. Around 94% of the original vegetation in the
wheatbelt region has been cleared, whereas the south-west forests are relatively intact,
making them an important refuge for populations (Burrows and Christensen 2002).
Chuditch have never been recorded in pure karri (Eucalyptus diversicolor) forest
(Orell and Morris 1994).
8
In the 1990’s, chuditch numbers in Western Australia had increased to 8,000,
seemingly in response to fox control efforts (Elsegood 1997). In 2000, following
ongoing fox control and animal translocation programs, it was estimated that there
were approximately 12,500 chuditch in the jarrah forest and 2,000 in the wheatbelt (K.
Morris, unpublished data 2000). Known populations of chuditch in Western Australia
occur in the jarrah forest (Batalling, Kingston, Perup, Hills Forest and the Northern
Jarrah forest), the hills district (Mundaring and Julimar Conservation Park), the
wheatbelt (Lake Magenta), Kalbarri and the southern coastal district (Mt Lindsey and
Cape Arid). The extent of occurrence in Western Australia now covers a roughly
triangular area from Moora in the north, Cape Arid in the east and Cape Leeuwin in
the south, covering an area of 360,000 km2 (K. Morris, unpublished data 2000) (Fig.
3). Recently, chuditch have also been sighted near Perth Airport, Midland, Gnangara
and Moore River, indicating a widespread return to the Swan Coastal Plain (Johnson
1999). Sightings of a chuditch at Wandi, a southern suburb of Perth, were confirmed
in June 2009 by an officer of the Department of Environment and Conservation
(DEC) (R. Dawson, pers. comm.). In 2007, a high density chuditch population (0.6
chuditch per km2) was identified 30 km south-east of Dwellingup by researchers at the
DEC Dwellingup Research Centre (IACRC 2007).
The former range of chuditch suggests they occupied a wide variety of habitats
including woodland, dry sclerophyll forests, beaches and deserts (Burbidge et al.
1988). Chuditch currently inhabit most kinds of wooded habitat within its current
range including eucalypt forest (primarily jarrah), dry woodland and mallee
shrublands (Serena & Soderquist 1995). In the jarrah forest, highest densities of
chuditch have been found in riparian vegetation, where the higher cover potentially
affords protection against predators and provides more reliable food resources (Orell
and Morris 1994).
Preferred dens of chuditch are located in horizontal hollow logs or earth burrows
(Orell and Morris 1994). Generally to be suitable as den sites, logs must have a
diameter of at least 30 cm but usually greater than 50 cm, with a hollow diameter of 720 cm. The den is typically 1 m or more from the entrance (Orell and Morris 1994).
Most earth burrows are located beneath surface features such as trees, stumps, logs
and rock outcrops. These provide increased protection from predators and/or supply
pre-existing channels or cavities for den construction (Serena et al. 1991). Nearly
70% of burrows examined in the jarrah forest were associated with either living trees
or their derivatives such as stumps, logs and the cavities created when trees are
uprooted or their stumps decompose (Serena et al. 1991). Chuditch have been
recorded sheltering in crevices among rocks in the south-west and arid inland (Morris
2000). An adult female will utilise an estimated average of 66 logs and 110 burrows
within her home range over a year (Orell and Morris 1994).
9
Fig. 3. Chuditch occupy the jarrah forest and woodland zone and have scattered distribution
(black dots) in the wheatbelt zone of south-west Western Australia
(adapted from Serena et al. 1991).
1.5 Key threats
Chuditch declined dramatically in number and distribution after European settlement.
Threats contributing to their decline include: land clearing and habitat alteration;
predation by, and competition with foxes and feral cats; changing fire regimes;
disease; and direct human impacts such as poisoning, illegal shooting and road kill.
Chuditch have a short average life span and are distributed patchily at low densities
within their present range, making them vulnerable to these threats and stochastic
events.
10
1.5.1 Feral animals
The European Red Fox (Vulpes vulpes), introduced to Australia from Europe in the
1930s, is a major threat to chuditch as a predator and competitor for food (Serena et
al. 1991). Circumstantial evidence that fox presence influences chuditch density is
revealed in long-term trends in capture rates of chuditch at the Perup jarrah forest, 50
km north-east of Manjimup. When monitoring commenced in 1974 prior to fox
control, the mean annual chuditch capture rate was 0.1%, which increased to 2.5% in
the 1990s following intensive, broad-scale fox control (Burrows and Christensen
2002). Generally, pre-fox control trap success at various locations in south-west
Western Australia varied from 0-0.7%, which increased to 1.5-8% in 1999 after the
introduction of fox control in the early to mid 1990’s (K. Morris, unpublished data
2000). A recent study by DEC researchers in and adjacent to forest within Alcoa’s
mining lease, has shown that while chuditch is patchily distributed across the
landscape, densities are on average higher in areas of fox control compared with
unbaited forest (A. Glen, unpublished data 2008). The introduced feral cat (Felis
catus), the dingo (Canis lupus dingo) and birds of prey also potentially impact
chuditch populations as predators and competitors for prey resources.
1.5.2 Habitat loss
Most habitat loss has resulted from forest clearing for agriculture, forestry, mining and
residential development. Clearing of forest results in removal of logs and other
suitable den and refuge sites (Orell and Morris 1994), and declines in availability of
prey such as small mammals, lizards, birds and invertebrates that rely on structural
forest components for habitat. It also results in the fragmentation of vegetation, which
may negatively influence the movements and foraging of chuditch given they have
large home ranges, and contribute to the patchiness of populations. In the jarrah forest,
land is managed for multiple purposes including timber harvesting, prescribed
burning, water catchment management, bauxite mining and recreation. Despite these
activities, chuditch have survived in the jarrah forest whilst declining elsewhere (Orell
and Morris 1994). In the wheatbelt where greater than 90% of vegetation has been
cleared, populations are very low and highly fragmented and are likely to remain so
until considerable area is revegetated (K. Morris, pers. comm.).
1.5.3 Prescribed burns
The fire ecology preferred by chuditch is poorly understood and is difficult to
investigate given their large home ranges and low population densities (Serena et al.
1991). Hot fires that decimate ground litter layers and woody debris are likely
detrimental for chuditch, because they result in dramatic declines in both biomass of
litter invertebrates (a primary component of the chuditch diet) and logs that are
suitable dens. Cool spring burns, which result in patches of unburnt vegetation
remaining, are probably preferable for chuditch because den logs are generally not
11
destroyed and invertebrate fauna recover more quickly. Indeed chuditch are able to
survive the current prescribed burning regimes (generally a five to seven year rotation)
undertaken in much of the jarrah forest and will utilise burnt areas for at least several
months following fire (Orell and Morris 1994). Similarly, Burrows and Christensen
(2002) noted that time since fire had no discernible impact on the capture rate of the
chuditch over 26 years of trapping at a jarrah forest site, with trends in capture rates
independent of burning.
1.5.4 Road kill, poisoning and illegal shooting
Road traffic is a current threat to chuditch populations, because individuals will forage
on live prey and carrion around road verges and camping areas, and will use dirt roads
to traverse their large home ranges (Morris et al. 2003). Based on the fates of radiocollared chuditch, being hit by motor vehicles at night is one of the major causes of
death at Lane Poole Conservation Reserve, and probably in other forest areas (Serena
et al. 1991). Regular road kills of chuditch in and around Alcoa’s mining lease are
reported on Alcoa’s ‘Fauna Sighting Record Sheet’, which is distributed across both
minesites for employees to record sightings of fauna. The most common occurrence of
road kill is along the access road into the Huntly mine, with 9 deaths reported in the
past 5 years. Most of the road kills result from staff driving to work for the evening
shift change.
Historically, chuditch have been persecuted in agricultural and rural regions because
as opportunistic predators they have exploited poultry as a food resource.
Consequently, they have been subject to poisoning, trapping and illegal shooting
(Morris et al. 2003). The present continuation of these practices is unknown. Shooting
and poisoning as a side effect of targeting other species, particularly rabbits
(Oryctolagus cuniculus), foxes and cats, probably also contributed to declines of
chuditch in some areas (Morris et al. 2003). Current baiting programs to control foxes
and dingoes use meat baits laced with the toxin 1080. Although present doses (4.5 mg
per 120 g of fresh meat) are considered to not be fatal to healthy adult chuditch,
ingestion may cause sickness and sterility, ingestion by young individuals may be
fatal, and toxins passed through milk can kill pouch young (Serena et al. 1991).
1.5.5 Disease
The limited and patchy distribution of viable chuditch populations leaves the species
vulnerable to decline due to disease (Serena et al. 1991). There is a widely held belief
that an epidemic disease caused a significant decline in all the large dasyurids early
last century (Belcher 2004), though this has not been substantiated.
12
1.6 Management actions
In 1992, the Chuditch Recovery Plan (Orell and Morris 1994) commenced with the
support of the Department of Environment and Conservation (DEC), Perth Zoo, the
World Wide Fund for Nature (WWF), Environment Australia and Alcoa. Over a ten
year period until 2001, $1.4 million was spent on recovery actions. Alcoa supported
the Chuditch Recovery Plan from 1992 – 1994 through grants provided to WWF,
contributing $42,900 in 1994 (Morris and Orell 1994). The recovery plan achieved its
objective to down list the chuditch from endangered to vulnerable in 2001.
1.6.1 Feral animal control
In 1996, the Department of Environment and Conservation (DEC) commenced a
large-scale feral predator control program called ‘Western Shield’. The program is
now applied to nearly 3.5 million hectares of land (primarily in national parks, nature
reserves and state forest), mostly in the south-west of Western Australia. The primary
aim of the program is to sufficiently reduce numbers of feral foxes through poison
baiting to allow affected native fauna to survive and recover. The baits are sausage
meat injected with 4.5 mg of sodium monofluoroacetate (1080), from the native genus
Gastrolobium. Native fauna tolerate the poison, while introduced predators that have
not evolved with the flora containing the poison are susceptible. Feral cats are also
targeted by the program, although control efforts have been hindered by lack of
efficient control techniques and limited reliability of available indices to accurately
assess changes in abundance. Additional aims of the Western Shield program are to
develop cost-effective and efficient fox and cat control mechanisms, communicate the
program to the public, and develop partnerships with groups and organisations for
implementation. Broad-scale baiting occurs at a rate of 5 baits/km2 four times per
year. The annual cost of the program is $1.25 million. Operation Foxglove was the
precursor to the Western Shield program and provided essential information for largescale operational baiting programs. It involved aerial baiting of foxes over 544,000 ha
of the northern jarrah forest to determine the optimal frequency of poison baiting
(unbaited versus 2, 4 and 6 baitings per year; de Tores 1999).
Alcoa contributes financially to feral predator control in the jarrah forest through
DECAFE (Department of Environment and Conservation/Alcoa Forest
Enhancement), which funds projects that enhance nature conservation, recreation,
landscape or heritage values of the northern jarrah forest. Through DECAFE, Alcoa
was a major supporter of the initial predator control program, Operation Foxglove,
providing funding of $140,000 per year. Alcoa continues to support Western Shield
with annual funding of $123,000 which is projected to increase to $135,000 in
2010/11. The program covers Alcoa’s entire mining lease in the northern jarrah forest
and includes an unbaited control section south-east of the Orion crusher region.
13
1.6.2 Habitat conservation
The return of fauna habitats in rehabilitated sites following mining operations in the
jarrah forest is an important component of Alcoa’s restoration process. Rehabilitated
areas are a young developing ecosystem and lack large woody debris required as den
sites for chuditch. To overcome this limitation, log piles are constructed in newly
rehabilitated areas using wood residue and rocks, creating potential habitat for
chuditch and other mammals, reptiles and invertebrates (Koch 2007). Following
clearing, some of the waste timber and rock boulders are left on the forest edge of
mine pits to be used for construction of fauna habitats after mining is complete.
Habitats are placed evenly throughout rehabilitated pits and are of various sizes and
shapes with suitable openings for fauna, constructed from large and small diameter
logs, tree stumps, rock and soil (Fig. 4). Alcoa’s completion criteria and working
arrangements with DEC require one constructed habitat per two hectares, however
Alcoa aims to exceed the government requirements and have an internal standard of
one constructed habitat per hectare. Alcoa first introduced habitats in rehabilitated
sites specifically for chuditch, however their use by chuditch has never been
measured.
Alcoa has a long-term fauna monitoring program (LTFMP) that was established in
1992 to monitor the effectiveness of restoration as it ages in providing habitat for
fauna including chuditch. It involves the monitoring of 20 sites for mammals, birds,
reptiles and ants every three years in healthy forest, dieback affected forest,
streamzones and rehabilitated areas at Huntly and Jarrahdale (mine closed and
returned to the management of the State Government). There has only been one
chuditch trapped in the history of the LTFMP, which was at Huntly at a dieback forest
site in 2001 (EMRC 2006). It is likely the generic trapping methods used are not
reliable for the census of chuditch, which being a highly mobile predator ideally
requires large trap spacing and a meat bait. The potential inadequacy of the trapping is
further supported by the frequency of chuditch sightings reported by employees at
Huntly on Alcoa’s ‘Fauna Sighting Record Sheet’. Other animal trapping programs
have recorded chuditch in unmined forest at Huntly (one chuditch at Chipala Road in
1999 and three at Yalara Road in 2005); rehabilitation at Willowdale (three chuditch
in 2007); and pre-mined forest at McCoy (five chuditch in 1998) (EMRC 1998; 2006;
2007). Alcoa undertakes pre-mining fauna surveys before entering new mining
regions to identify any rare or protected species and determine if certain habitat areas
should be avoided in the construction of infrastructure such as haul roads and
conveyer alignments. Alcoa is presently investigating ‘wildlife underpasses’ for safe
fauna movement across mining haul roads (Harris 2007).
14
Fig. 4. A fauna habitat returned to post-mining rehabilitation, constructed from piles of logs,
rocks and soil.
Cooler spring burns resulting in patches of unburnt vegetation are probably preferable
for chuditch compared with wildfires that will result in higher mortality of individuals
and greater loss of den habitat and invertebrate food resources. Alcoa has 15 years of
research on fire in restored areas that demonstrates when rehabilitation can be
integrated with prescribed burning of surrounding unmined forest. The most
appropriate prescribed fire regime is low to moderate intensity spring burns when
restoration is 13-15 years old and all components of the ecosystem are able to recover
post burning (Grant et al. 2007). Alcoa provides funding as part of the Alcoa/DEC
Associated Works program for DEC to undertake mine protection prescribed burns in
the mosaic of rehabilitation and unmined forest within the mine lease. Forest is burnt
on an 8-15 year rotation to reduce fuel loads and the likelihood of an area carrying an
intense wildfire. Riparian vegetation along streams is protected from fire where
feasible, and this may provide valuable unburnt habitat for chuditch within the forest
mosaic of varying time since burn. In a study of the impacts of fire on mammals at
Alcoa’s Jarrahdale mine-site, captures of chuditch were too low to elucidate the
impacts of fire on this species (EMRC 2004).
1.6.4 Community awareness
The chuditch is a unique looking animal that has appeal to the community. Perth Zoo
plays an important role in raising awareness of the chuditch within the community and
gaining support for its conservation. Perth Zoo led a community involvement
15
program, which Alcoa contributed to in 1995 by donating $25,000 (Morris and Orell
1995). Friends of the Chuditch (Inc.) also raise community awareness through the
circulation of ‘The Chuditch Chat’ newsletter, public information displays, and talks
to primary and secondary schools in Perth and country areas. Raising community
awareness of the vulnerable status of chuditch will hopefully result in a decline in
illegal shootings, particularly given their status may not be known broadly within the
community.
1.6.5 Animal breeding and translocation
Many areas of apparently suitable habitat within the south-west of Western Australia
lack populations of chuditch (Serena et al. 1991). The Native Species Breeding
Programme (NSBP) at Perth Zoo involved captive breeding of chuditch sourced from
the jarrah forest (Fletcher and Morris 2003). The breeding program ran from 1990 –
2000 and was an action under the Chuditch Recovery Plan, supported by DEC, Alcoa,
World Wide Fund for Nature (WWF) and the Australian Nature Conservation
Agency. The goal of the NSBP was to provide animals for release to the wild, to
conduct scientific research into the reproductive biology of the species and to increase
public awareness through the Zoo’s Education Programme (Fletcher and Morris
2003). Since the captive breeding programme began at Perth Zoo, 311 chuditch have
been bred for release into habitat under predator control (Fletcher and Morris 2003).
Translocations from wild populations were not considered feasible due to the low
densities (Serena et al. 1991).
Translocation sites include Julimar Conservation Park (north-east of Perth), Lake
Magenta (wheatbelt), Mt Lindesay (near Denmark), Cape Arid National Park (200 km
east of Esperance) and Kalbarri National Park. In 1992, Julimar Conservation Park
was the first translocation site, and populations are now well established (Johnson
1999). The first translocation to the wheatbelt site of Lake Magenta occurred in 1996,
with a total of 81 chuditch released there over a couple of years (Johnson 1999).
Breeding at Lake Magenta has occurred and in 2000 the trap success rate had
stabilised at 3.8-4.8% (K. Morris, unpublished data 2000). In 1998, 40 chuditch were
released into Cape Arid National Park, which contains a mixture of coastal and semiarid vegetation. Breeding at Cape Arid has also occurred, however trap rates varied
between 1.4 – 5.5% and did not indicate a population increase (K. Morris,
unpublished data 2000). Translocations occurred in a variety of different habitat types
to study the species survival and breeding in each and increase the number of
population sources to safe guard against natural environmental events.
Considerable research was required to successfully breed chuditch in captivity. In
1994, a MSc research project investigated physiological changes associated with
reproductive changes through the annual cycle to discover when the chuditch was
most likely to reproduce, which helped make the Perth Zoo breeding programme so
16
successful (Elsegood et al. 1997). The breeding for release programme at Perth Zoo
ceased in 2000 following the chuditch being down listed from endangered to
vulnerable status.
1.6.6 Research initiatives
From 2006 to 2009, Alcoa established long-term experimental trials to identify
optimum densities and spatial arrangement of coarse woody debris in post-mining
forest rehabilitation to encourage fauna return. The trial will help determine the
optimum density of fauna habitats to maximise return and use of rehabilitation by
chuditch and the value and persistence of fauna habitats through time. The trial will
be monitored for the next 15 years to measure animal recolonisation and
establishment as rehabilitation matures. Recent research on the effect of wildfire on
fauna habitats determined that fauna habitats do persist through a hot summer wildfire
(A. Grigg, unpublished data 2007). Generally, there was an overall reduction in the
number of logs but very few were completely consumed, with stumps and rocks
remaining intact. The cooler prescribed burns that occur in rehabilitated sites should
have only a minor impact on the habitat value of the log piles, though their persistence
over time and through multiple burns needs to be determined.
1.7 Recommendations
The following actions are recommended for managing chuditch in Alcoa’s mining
lease:
 Develop and implement a chuditch specific monitoring program to obtain
reliable measures of chuditch distribution and density within the mining lease
and monitor mining impacts. This should be incorporated into the LTFMP.
 Collaborate with DEC to research chuditch return into rehabilitation and their
use of fauna habitats relative to habitat use in surrounding unmined forest.
 Encourage and educate Alcoa staff and contractors to remove fresh road kill
from the mine access roads, so that carrion is not on the road attracting
chuditch. This will hopefully reduce the incidence of road kill of chuditch on
the mine-sites.
 Determine from Alcoa’s Fauna Sighting Records and road kill monitoring
where chuditch road kills commonly occur in Alcoa's mine lease and erect
warning signs to alert motorists to the occurrence of chuditch.
 Use LTFMP and fauna research data, and invertebrate biomass studies to
compare prey availability for chuditch in rehabilitation and unmined forest.
 Research the effect of prescribed burning and wildfires (where opportunity
arises) on den availability for chuditch in rehabilitation and unmined forest.
 Continue financial support for feral predator control in the northern jarrah
forest through continued contribution to the Western Shield program.
17
 Train Alcoa staff and consultants in accurate identification of chuditch to
increase reliability of sighting records on Alcoa’s ‘Fauna Sighting Record
Sheet’.
18
2. QUOKKA (Setonix brachyurus)
The quokka is listed as "Declared Threatened Fauna: Schedule 1 - Fauna that is rare or
is likely to become extinct" under Western Australia's Wildlife Conservation Act
1950. The quokka was listed as vulnerable under the federal Environment Protection
and Biodiversity Conservation (EPBC) Act 1999 in July 2000. It has a ranking under
World Conservation Union criteria of “Vulnerable C1: population reduction in the
form of an observed, estimated, inferred or suspected reduction of at least 10% over
the last 10 years or three generations” (IUCN 2007).
The quokka (Setonix brachyurus Quoy & Gaimard 1830), also known as the scrubwallaby is a nocturnal, medium-sized macropod that is endemic to the mesic, southwestern corner of Australia. The name "quokka" was given to the animal by the
Aboriginal people living in the Augusta and King George Sound area of the southwest of Western Australia. The first written description of the species came from
Dutchman Samuel Volckertzoon in 1658 who described it as “a wild cat resembling a
civet-cat but with browner hair” (Kitchener 1995). In 1696, de Vlamingh described
the quokka as "a kind of rat as big as a common cat" during his discovery of Rottnest
Island. The island was named 'Rotte nest' (meaning 'rat's nest' in Dutch), which was
eventually adapted to 'Rottnest'.
The quokka is the only member of the genus Setonix. It is considered sufficiently
different from kangaroos and other wallabies in the genus Macropus to be placed in
its own genus and is thought to have diverged early from the evolutionary lineage that
gave rise to the browsing marsupials (Van Dyck and Strahan 2008). Quokkas weigh
between 1.7 - 4.2 kg, with a body length range of 40-54 cm and tail length of 25-30
cm (ZPGPB 2004). The fur is thick, coarse and grey-brown with lighter underparts
(Fig. 5). They have rounded ears and a short, broad head with a dark stripe on the
forehead. The quokka has strongly developed hind legs enabling it to hop. Quokkas in
the northern jarrah forest exhibit sexual dimorphism with males being significantly
larger than females (Sinclair 1998; Hayward et al. 2003). There is a general trend for
animal size to decrease with latitude (Sinclair 1998). There is seasonal variation in tail
circumference, indicating quokkas possess caudal fat deposits (Hayward et al. 2003).
19
Fig. 5. A female Quokka (Rottnest Island Authority 2007).
Quokkas can live for over ten years in the wild (Holsworth 1967; Nowark 1999).
Mainland quokkas breed throughout the year, with lowest numbers of births occurring
in summer when female body weight drops and nutritional status of females affects
their reproductive performance. Island quokkas breed seasonally with the majority of
births occurring between February and April (Shield 1964; Hayward et al. 2003).
Quokkas begin breeding at one to two years of age. Females have a gestation period of
26 to 28 days and in the northern jarrah forest can wean two to three young per year,
although there is a high rate of pouch mortality with only 40% recruitment rate of
pouch young to adult (Hayward et al. 2003). On Rottnest Island females only
successfully produce one young per year. Young remain in the pouch for the first 25
weeks and then on-foot continue to suckle from the mother for a further 10
weeks. Young can associate with their mothers up to two years of age, sharing the
same rest sites or using an adjacent one (Kitchener 1972). The population in the
northern jarrah forest is comprised of 50% adults, 25% juveniles and 25% pouch
young (Hayward et al. 2003).
Females are polyestrous, having more than one breeding cycle (Shield and Woolley
1960). After young are born, the female mates and goes into embryonic diapause,
20
where the embryo is dormant. If the young in the pouch die within five months, the
embryo in diapause resumes development. If the young lives, the embryo degenerates
when the female enters anoestrous. When conditions are good the second embryo can
resume development after the first young is raised.
Quokkas have a well developed social organisation composed of family groups in
which adult males are dominant and adult females and juveniles have no social rank
(Kitchener 1972). Males form a linear hierarchy in which the older adults rank higher
than the younger. The social rank has a low number of reversals resulting in a stable
hierarchy (Kitchener 1972). Long-term individual associations occur between male
and female adult quokkas. The quokka is mostly nocturnal, sleeping during the day
amongst dense vegetation at permanent chosen rest sites (Nicholls 1971; Kitchener
1972; Hayward 2005), although mainland quokkas tend to rest near to where they
ceased their nocturnal activities rather than a regular rest site (Hayward et al. 2004).
Male quokkas defend territory, particularly in the vicinity of their rest sites. Defensive
behaviour includes chasing, biting or striking with the paws and feet (Kitchener
1972). Quokkas become active at night, when up to 150 individuals gather to feed.
The distance of movement from the rest site to feeding areas varies from 50 to 600 m
on Rottnest Island (Nicholls 1971). They have been observed to climb trees up to 1.5
meters, an unusual behaviour for macropods, and are also strong swimmers (White
1952).
2.3.2 Diet
Quokkas are generalist browsing herbivores and feed on native grasses, leaves, seeds
and roots (Hayward 2005). They swallow their food and later regurgitate the cud to
chew. Like ruminants, they have bacteria in the digestive system to digest cellulose
and starch (Moir et al. 1956). On Rottnest Island, feed plants include Acacia
rostellifera, Carpobrotus aequilateris, Thomasia cognata, Rhagodia baccata, Gahnia
spp., Scaevola spp. and the succulent swamp species Arthrocnemum halocnemoides
(Holsworth 1967; Nicholls 1971; Kitchener 1972). In the northern Jarrah forest, diet
of quokkas varies seasonally and spatially. Localised extinctions have been attributed
to poor dietary diversity at sites that lack the preferred recently burnt forest within a
habitat mosaic of long unburnt forest (Hayward 2005).
Quokkas have relatively high water requirements. Quokkas on Rottnest Island can
lose up to 240 mL of water per day during the summer (Storr 1964a) and so succulent
plants provide an important source of water. Quokkas have been observed to dig for
water, however they can go for months without water due to their ability to internally
reuse some of their waste products.
21
Quokkas were once wide-spread across mainland Western Australia, with fossil
deposits suggesting that they originally occupied an area of approximately 49,000 km2
over a distribution of 116,000 km2 (Hayward 2002). Prior to the 1930’s, quokkas
were plentiful and ubiquitous, commonly seen grazing in pastures (White 1952; de
Tores et al. 2007). In fact they were considered vermin and were regularly hunted
commercially (Government Gazette of Western Australia 1933; Prince 1984). They
were thought to have occurred from the Moore River north of Perth to Esperance on
the south coast (Shortridge 1909), covering the Swan Coastal Plain, Jarrah forest,
Warren and possibly Esperance biogeographical zones (Thackway and Cresswell
1995). Since the 1950s, the mainland area occupied by the quokka has declined by
45% and since 1990 by an additional 29% of its original range (Hayward et al. 2002).
Today, quokkas occupy 20,000 km2 and occurrence is now generally restricted to
swamp thickets in forest or coastal shrublands in south-western Western Australia
(deTores et al. 2007). Present populations appear fragmented and are considered to be
in a state of collapse with the localised extinction rate exceeding the colonisation rate.
For example, quokkas were locally extinct or on the verge of localised extinction at
four of the eight swamps with known quokka populations in the northern jarrah forest
(Hayward et al. 2003). The isolation of populations and reduced gene flow may be
contributing to the high incidence of decline on the mainland. Presently the quokka
extends from south of the Perth metropolitan area to Collie in isolated patches within
the northern jarrah forest. Populations are widely scattered up to 40 km apart, occur
within small and isolated patches of suitable habitat, and are low in number ranging
from 1 to 36 individuals (Hayward et al. 2003). This is below the minimum viable
population size (50), often speculated as delineating genetic problems such as
inbreeding depression and loss of heterozygosity (Caughley 1994). The overall
quokka population size in the northern jarrah forest may be as low as 150 adult
individuals (Hayward et al. 2003). Quokkas appear to be discontinuous from Collie to
Nannup, and then extend through the southern jarrah, marri and karri forests (Nannup
to south of Northcliffe) to the south coast (Fig. 6). Populations within the southern
forest region appear to be more contiguous than those in the northern jarrah forest.
Isolated mainland populations are known from east of Albany (Waychinicup National
Park), several locations within the Stirling Range National Park and from Green
Range (de Tores et al 2007). Quokkas also occur on Bald Island and in high numbers
on Rottnest Island. They are thought to no longer occur on the Swan Coastal Plain (de
Tores et al. 2007).
Rottnest Island is the only place where quokkas occur at high density. It supports a
population which has temporarily high numbers of up to 10 000 to 12 000 individuals
(Dickman 1992; O’Connor 1999) but seasonally falls to a much lower population size
in late summer (P. deTores, pers comm.) due to the harsh environmental conditions
that cause weight loss, anaemia and heat-stress among individuals (Kitchener 1972).
22
Rottnest Island is thought to have separated from the mainland approximately 7,000
years ago. Despite this there is no evidence the island quokka population differs
genetically from mainland conspecifics (Sinclair 2001), other than reduced genetic
diversity (Alacs 2001). It appears environmental differences between the mainland
and Rottnest Island have influenced the relative success of populations, namely the
absence of the fox on the island (deTores et al. 2007). Rottnest Island supports harsh
and highly disturbed habitats of cleared vegetation and has a limited supply of fresh
water, suggesting that quokkas can be habitat adaptable in the absence of feral
predators.
Fig. 6. Distribution of the Quokka as of 2000. Stars indicate known occurrence while open
circles are possibly extinct populations. The filled area shows the area of occupancy while
the solid line shows the extent of occurrence. The 700 mm (dotted) and 1000 mm (short
dashed line) annual rainfall isohyets are shown (Hayward 2002).
The northern jarrah forest of Western Australia is the northern limit of quokka
distribution on the mainland. Five known populations of quokkas occur in the
northern jarrah forest at Chandler, Hadfield, Kesners, Rosella Road and Victor Road
(Fig. 7). They occur in peppermint (Taxandria linearifolia), bullich (Eucalyptus
megacarpa) and paperbark (Melaleuca rhaphiophylla) swamps. Peppermint swamps
are tall, closed shrublands dominated by T. linearifolia, with Leptospermum
tetraquetrum, Gahnia decomposita and Astartea fasicularis in the sedge-dominated
understorey. Bullich swamp forests occur as small fragments within the swamps and
are dominated by a canopy of E. megacarpa and an understorey of T. linearifolia,
23
Hypocalymma cordifolium and Boronia molloyiae. Paperbark (M. raphiophylla)
swamps occur as pockets within the peppermint swamps. Surrounding all three types
of swamp is open forest dominated by bullich and blackbutt (E. patens) with a shrub
understorey of Bossiaea aquifolium, Mirbelia dilatata and Thomasia species. This
gives way to typical jarrah (E. marginata) and marri (Corymbia calophylla) forest on
the lateritic slopes and ridge tops of the Darling Plateau (Hayward et al. 2005).
Quokkas show a distinct preference for peppermint swamps and do not inhabit the
forests surrounding the swamps (Hayward et al. 2005). The peppermint swamp
patches occur in the upper reaches of creek systems and are separated from each other
by at least a few hundred metres. The home range of the quokka is 6.39 ha with a core
range of 1.21 ha. Given the linear nature of the quokkas preferred riparian habitat, the
average home-range size equates to 600 m along the swamp and 100 m across it.
There appears no movement of individuals between swamp populations (Hayward et
al. 2004).
Fig. 7. Location of five known quokka populations at Chandler, Hadfield, Kesners, Rosella
Road and Victor Road in the northern jarrah forest (Hayward et al. 2004).
24
The quokka populations in the northern jarrah forest occur in swamps supporting a
complex mosaic of recently burnt and long unburnt areas. They have a preference for
swamps that have recently (<10 years) been burnt by fire, probably related to the
abundant availability of fresh foliage within foraging reach (Hayward et al. 2005).
While feeding occurs in recently burnt areas, quokkas may not be resident there for at
least a year until vegetation cover develops and provides refuge while foraging.
Additionally, the persistence of older, unburnt habitat within (<100 m) or adjacent to
foraging areas in recently burnt swamps provides important, potentially vital, refuge
habitat (Hayward et al. 2005). Quokkas have been observed foraging within burnt
swamps less than three months after fire, reaching peak abundance in swamps that
were burned less than 12 years previously, and then deserting the habitat after 15 years
(Christensen and Kimber 1975).
2.5 Key threats
Invasive predators are a key threat to quokkas, contributing directly to declines and
local extinctions of populations, as well as to quokka reliance on swamp habitats.
Loss of preferred habitat through disturbance, clearing and changes in fire regimes of
swamplands has also contributed to increasing fragmentation and declines in quokka
populations throughout the jarrah forest, although in the absence of feral predators
quokkas may be able to take advantage of other more open vegetation types. Clearing
of habitat for urban development was likely a large contributor of quokka declines on
the Swan Coastal Plain.
2.5.1 Feral animals
One of the major threats to quokkas is the European Red Fox (Vulpes vulpes),
introduced to Australia from Europe in the 1930’s. The initial dramatic reduction in
the quokka population during the 1930’s corresponds closely in time with the
introduction of the fox (White 1952). The quokka, weighing 1.6 to 4 kg, falls within
the critical weight range (35 g – 5.5 kg) of native mammal that is most susceptible to
predation by the fox (Burbidge and McKenzie 1989). Evidence of direct impacts of
foxes due to predation can be seen in prey responses to fox control. While there is no
direct quantifiable response by quokkas to fox control (Hayward et al., 2003) (likely
due to the fragmented nature of populations), the occurrence of fox control does
appear to be an important predictor of the presence of quokkas in the northern Jarrah
forest (Hayward et al., 2007). There is also anecdotal evidence to suggest that quokka
numbers have increased elsewhere in response to fox control (P. Collins, J. Friend,
pers. comm.).
The quokka’s present restriction to swamps on the mainland is probably not because
adjacent forests and farmlands are unfavorable (these areas were commonly used by
quokkas prior to the introduction of the fox), rather predation risks and predation
25
events are higher in these more open habitats. Sub-lethal effects of foxes such as
altered foraging behaviour of quokkas (Sinclair et al. 1998), as well as direct
predation likely contributed to present fragmentation of populations across
swamplands. Furthermore, by suppressing population booms that are required to drive
dispersal and maintain metapopulation dynamics, fox predation likely continues to
maintain and exacerbate the fragmented status of the quokka (Hayward et al. 2004).
Feral cats (Felis catus), also a potential predator of quokkas, are not considered to be a
driving factor behind the dramatic decline of the quokka as they generally prey on
smaller mammals (<1 kg) (Dickman 1996). Additionally, there is no clear evidence
that cats prey on quokkas. For example, prior to the 1980’s when cats were common
on Rottnest Island, there was no observable effect on quokka numbers. However,
populations on Rottnest Island are atypically high and it is possible that low rates of
predation by cats may push small isolated populations such as those on the mainland
into rapid decline (Sinclair et al., 1998), particularly given cats likely prey on
juveniles, aged and sick individuals. Feral cats also indirectly cause deaths through the
transmission of diseases such as the protozoan, parasitic disease toxoplasmosis
(Hayward 2002).
Feral pigs have the potential to indirectly affect quokkas through destruction of habitat
caused by digging in swamps. Pigs disturb large tracts of land by removing vegetation
and leaf litter and disturbing the upper soil profile in their search for food (Laurance
1997). This disturbance likely reduces food availability for quokkas and results in the
creation of pathways in the vegetation that reduce available cover and facilitate access
of dense vegetation for foxes (Meek and Saunders 2000). It has been suggested that
swamp habitats that previously supported quokkas, are no longer habitable after the
disturbance of these areas by pigs (P. de Tores, J. Hampton, pers. com.). The role of
pigs in the decline of native fauna has not been examined and is likely underestimated.
2.5.2 Habitat loss
Much of the coastal heath and shrubland habitats in the south-west of Australia where
quokkas once occurred have been cleared for urban development. The coastal plain
from north of Perth to Busselton has very few pockets of undisturbed vegetation
remaining, with remaining fragments small and highly susceptible to invasion by
predators (Hayward 2002) and it is these factors that are likely responsible for quokka
absence from these areas.
The northern jarrah forest is subject to forestry, mining and forest clearing for rural
and agricultural development, all of which result in some level of disturbance of
quokka habitat or adjacent forest. Forestry and mining are not likely to have direct
impacts on quokka habitat because of legislated requirements to maintain a minimum
26
50 m of buffer vegetation around stream and swamp areas (the preferred habitat of
quokkas). This is because stream zone vegetation is classified as informal
Comprehensive, Adequate and Representative (CAR) reserves of high conservation
value by the Commonwealth of Australia and the State of Western Australia’s
Regional Forest Agreement 1999, and disturbance requires special approval. Also,
mining does not encroach on swamp areas because economically viable deposits of
bauxite ore do not occur in valleys within the jarrah forest, but in upland forest.
Alcoa’s mining operations do cause direct disturbance of stream zone vegetation when
haul roads are required to cross stream zones to gain access to areas of ore. Also, past
mining operations (prior to 1999 and before quokka populations in the northern jarrah
forest were first identified) involved damming streams for the life of the mine to
provide a water supply. These operations would have impacted some quokka
populations. For example, in the late 1980s, the Chandler swamp quokka population
at Jarrahdale was likely disturbed when Alcoa constructed a dam to supply water to
the bauxite mine, which flooded a large portion of the swamp. The decommissioning
of the dam in 2000 was carefully planned to release water in stages over
summer/autumn to minimise flooding and siltation of the swamp. The quokka
population at Rosella Road swamp at Jarrahdale, and the population at Wild Pig
swamp at Huntly may have inadvertently been disturbed when haul road crossings
were built prior to 1999. The quokka population at Kesners swamp near Del Park and
North Spur Roads, adjacent to Alcoa’s Del Park mine, has a conveyor belt through the
upper-most section of the swamp and land has been cleared. Clearing and the
conveyor noise may inhibit quokka movement, and several areas adjacent to the
swamp have been mined (Hayward 2002). Presently, local populations may be
affected by the large-scale clearing operations adjacent to swamp habitats and the
resulting fragmentation of the jarrah forest, which may impede quokka dispersal and
colonisation of potentially suitable habitat. There are four known quokka populations
in the northern jarrah forest localised around Alcoa’s Jarrahdale and Huntly mining
regions.
Despite forest clearing for forestry, mining and agriculture, peppermint swamps
remain common in the northern jarrah forest and thus habitat availability is not likely
limiting the population growth of the quokka in this region (Hayward et al. 2005).
However, these activities do disturb forest habitats adjacent to swamps and stream
zones and as such may facilitate the movement of feral animals such as foxes and pigs
into areas of preferred quokka habitat. All quokka populations in the jarrah forest are
well below the carrying capacity of each site (Hayward et al. 2003) and the precise
causes of this are unknown. The high numbers of quokka that occur in the seasonally
arid and harsh environment of Rottnest Island, suggest that the quokka is adept at
successfully inhabiting areas other than dense, moist vegetation, and that
combinations of clearing, feral predators and fire are threats for mainland populations.
27
Within the northern jarrah forest, a mosaic of long unburnt areas and recently burnt
areas (burnt within the previous 10 years) is considered important for the persistence
of quokkas (Hayward et al. 2007). Historically, low intensity burns were undertaken
by Aboriginal people for hunting purposes and sections of swamps were directly
ignited to flush animals into the open. Vegetation was burnt every three to four years.
These small-scale burns contrast with the less frequent, but larger scale, prescribed
burns that are undertaken today. Broad scale burns do not create a mosaic of seral
vegetation stages favoured by the quokka (Hayward et al. 2005). Additionally, many
stream and swamp areas are presently not subject to prescribed burning so as to
protect these areas as habitat for the Noisy Scrub-bird, a threatened species that is
highly susceptible to the effects of fire (see page 35). The upper limit of the long
unburnt component of the habitat mosaic required by quokkas is unknown, as is the
configuration of the mosaic.
2.5.4 Phytophthora cinnamomi
Fauna such as the quokka, which is dependent on complex forest structure for food,
shelter and protection from predators, is potentially threatened by dieback caused by
the soil-borne pathogen Phytophthora cinnamomi. While swamp and stream-zone
vegetation in the northern jarrah forest is less impacted by P. cinnamomi, adjacent
jarrah forest can be devastated by the pathogen which can cause massive tree and
under-storey death. This opening of the forest structure can inhibit dispersal of
quokkas to new stream habitat and can facilitate access of feral animals such as foxes
and pigs.
2.5.5 Disease
Disease has not been demonstrated as an important factor in the decline of the quokka,
but has been implicated as responsible for the death of individuals (de Tores et al.
2007). Potential disease threats include Salmonella infection, thought to be common
on Rottnest Island (Hart et al. 1986), and Toxoplasmosis observed in populations of
quokka (Gibb et al. 1966). Quokkas have previously been shown to react to a pox
virus (Papadimitriou and Ashman 1972) and there is recent concern that quokkas
could become infected with the canary pox virus, the basis for the vaccine for equine
influenza virus, used extensively in 2007 to protect the horse industry from outbreaks
of equine influenza (D. G. A. Gibb, pers. comm.). The small size and physical
isolation of mainland populations means they are at risk of local extinction due to
disease outbreaks (Sinclair 2001).
28
2.5.6 Climate Change
Mainland quokkas are largely confined to streams and swamps in areas that receive
greater than 700 mm of annual rainfall (de Tores et al. 2007). This is probably linked
with reliance both for green digestible vegetation and water. In south-west Western
Australia, rainfall has been predicted to decline by as much as 20% from rainfall
recorded for the period 1960-1990 (Hennessy et al. 2007). Such drying effects are
likely to have direct and indirect impacts on quokka populations, including
contraction of swamp and riparian habitats and subsequent reductions in food
availability and predation refuges.
In 2008 a management plan for the quokka was drafted by the Research Division of
the Department of Environment and Conservation (DEC) and is currently under
review by members of the Recovery Team. An active adaptive management
framework is recommended, using fox baiting to control predators and fire to enhance
the preferred habitat of the species. Known populations of quokkas in the northern
jarrah forest should be managed as separate entities rather than a metapopulation until
structure is restored and connectivity of populations can be facilitated (Hayward et al.
2003). Population monitoring and reporting is necessary to determine conservation
gains or management changes required against the target outcomes. Currently, known
quokka populations are generally not monitored in a consistent manner, if at all (de
Tores et al. 2003).
Alcoa contribute to fox control in the northern jarrah forest through annual DECAFE
(DEC/Alcoa Forest Enhancement) funding of the Western Shield program
implemented by DEC (see page 10). Baiting of feral predators is increased in and
around sites known to support populations of quokkas because of concerns about the
stability and persistence of these potentially isolated populations. Typically baiting
with 1080 poison is conducted four times a year, but occurs monthly at a higher
intensity of one bait every 100 m around the five known quokka populations in the
jarrah forest. Alcoa has provided funding through the Alcoa/DEC Associated Works
program of $4,000 - $8,000 per year since 2001 towards the monthly hand-baiting of
known populations of quokkas at Jarrahdale and Huntly. The Alcoa/DEC Associated
Works program funds work such as fire protection, forest access and fauna protection.
Despite fox baiting, populations of quokkas in the northern jarrah forest have not yet
shown a measurable increase in size (Hayward et al. 2003), though populations have
not been recently monitored to determine the long-term benefits of more intensive
control around quokka swamp habitats.
29
Prescribed burns on a 5- to 10-year-rotation are required to facilitate conservation of
the quokka (Hayward et al. 2005). The fires should be patchy, to ensure that a finescale mosaic of refuge and foraging habitat is available for surviving quokkas, and
small scale to minimise direct mortality (Hayward et al. 2005).
Alcoa provides funding as part of the Alcoa/DEC Associated Works program to
undertake mine protection control burns. Forest is burnt on an 8-15 year rotation to
reduce fuel loads and the incidence of wildfire. The burns are undertaken by DEC,
generally in large blocks of forest. Fire management of swamps with quokkas is
managed separately. Presently, quokka swamps are generally excluded from control
burns because of uncertainty about the fire tolerance of this species and concerns
about negatively impacting their required habitat. An opportunity exists to enhance
potential quokka habitat by tailoring burns to create fine-scale mosaics of seral
vegetation stages. However, the preferred spatial configuration and relative proportion
of each burn seral stage is unknown. The maximum period of time without fire in the
long-unburnt component of the mosaic is also unknown. It is recommended that the
existing Taxandria swamps are stratified according to time since fire in combination
with spatial analyses of existing, historic and potential quokka sites to determine if
swamps can be better managed through the use of fire to support quokka populations.
Burning of small patches should also be trialled to determine the logistics of this
management practice.
In the northern jarrah forest, many apparently suitable patches of peppermint swamp
remain unoccupied by quokkas. It is possible that with predator control and an
associated increase in quokka densities, individuals may colonise these patches and
establish viable populations. This should be facilitated by conserving adequate habitat
patches with connecting corridors for dispersal (Sinclair 2001). Alcoa is investigating
possibilities to reduce habitat fragmentation from haul road construction by installing
fauna underpasses. These will potentially provide quokkas with a safe means of
traversing roads so habitat utilisation and genetic exchange can be maintained (Harris
2007). Today, operations around the known quokka populations are managed to
minimise disturbance but the absence of information on the location of any additional
quokka populations is a limiting factor for conservation efforts.
Alcoa’s long-term fauna monitoring program (LTFMP) and ‘Fauna Sighting Record’
system may help identify new quokka populations or quokka movements away from
known swamp habitats. Quokka sightings were recorded at Huntly and Larego in 2006
and 2008 (EMRC 2006). It is important the quokka habitats identified at Larego are
protected as the new mining region develops. Sightings of quokka and road kill have
30
been reported by Alcoa staff near Kesners swamp and at a swamp along the Huntly
access road (potential new population).
Perth Zoo is running a successful captive breeding program for the quokka that may
provide sources of individuals for translocation to uninhabited swamps in the jarrah
forest. Such ex situ conservation programs are important for ensuring the conservation
of unique genotypes, particularly given the risk of local extinctions of small isolated
populations (Alacs 2001). Translocation of individuals between large highly
differentiated populations is not recommended as it can result in the loss of local
adaptations and lead to out-breeding depression. However, the priority should be to
identify and monitor existing populations and manage adjacent habitat to facilitate
dispersal, because translocated populations will face the same issues of isolation
current populations do and in all likelihood will not be viable without appropriate
management of the habitat. Fire could be used firstly to create the quokkas preferred
habitat in unoccupied swamps, after which quokkas that have been bred ex situ are
translocated to initiate new populations.
Quokkas on Rottnest Island were extensively studied during the 1960s and 1970s due
to the ease of capture and handling. The mainland populations have only recently been
studied with efforts hampered by low population densities, low capture probability
related to trap shyness and difficulties accessing quokka habitat (Sinclair 1998;
Hawyard et al. 2003). In 2001, Alcoa provided $15,000 to support research by DEC at
Dwellingup on quokkas in the northern jarrah forest, which led to the identification of
5 quokka populations and information on their preferred habitat and requirements for
recently burnt swamp habitat.
PhD research on the southern mainland populations around Manjimup and Walpole
commenced in January 2007 by Karlene Bain (DEC). This is the first time quokka
populations in the south-west forests will have been studied in detail. The research
aims to identify: 1) whether reliable estimates of quokka abundance can be obtained
from indicators of activity including scats, tracks and runnels; 2) whether landscape
features such as topography and geomorphology can be used to predict the occurrence
of quokkas; 3) the distribution and abundance of quokkas in the region and how this is
influenced by fire history and the presence of feral pigs; and 4) whether subpopulations constitute a functional meta-population.
Alcoa, DEC and the Serpentine-Jarrahdale Community Landcare Group have recently
discussed forming a partnership to work collaboratively on quokka research and
conservation in the northern jarrah forest. DEC and the Serpentine-Jarrahdale
31
Community Landcare Group submitted a Caring for our Country (CfoC) application,
but it was unsuccessful. Any future collaboration will focus on using the information
available on the northern jarrah forest quokka populations to form an adaptive
management plan to implement at Jarrahdale. The response of the quokka
populations will be monitored to determine the most effective approach, which may
then be applied to other regions including Huntly. The partnership also aims to initiate
further research that will build on existing knowledge, such as: i) testing the
metapopulation hypothesis by undertaking further genetic analysis of populations
(Alacs 2001); and ii) assessing pig damage to quokka habitat.
2.7 Recommendations
The following actions are recommended for managing the quokka in Alcoa’s mining
lease:
 Continue annual financial support for intensive fox baiting around known
quokka populations at Huntly as part of the Alcoa/DEC Associated Works
program.
 Conduct targeted quokka surveys in suitable swamp/stream vegetation as part
of pre-mining fauna surveys within new mine regions at O’Neil, Larego and
Myara; particularly areas proposed as sites for haul road stream crossings.
Investigate rapid and reliable survey options for identifying quokka presence in
streams and swamps, such as motion sensitive cameras and/or DNA analysis
of scats/hairs.
 Map locations of new and known quokka populations on Alcoa’s GIS and use
this information to manage mining impacts and protect quokka habitat through
informed planning of haul road construction at stream crossings and
consideration of haul-road fauna underpasses.
 Install a haul road fauna underpass at a stream crossing and monitor its
effectiveness in facilitating movement of quokkas and other fauna up and
down the stream. Design and construction should be based on the
recommendations of a desktop study (Harris 2007).
 Likewise investigate quokka use of standard culverts under haul roads at
stream crossings and trial drift fences encouraging fauna to cross under rather
than over roads.
 Collaborate with DEC scientists and operational staff to manage known
quokka populations through prescribed burn planning and modelling preferred
seral ages since fire.
 Contribute to efforts to understand mechanisms for ongoing low numbers of
quokka despite fox control by supporting research of pig impacts on quokkas
and their habitat.
32
 Determine from Alcoa’s Fauna Sighting Records and road kill monitoring
where quokka road kills commonly occur in Alcoa's mine lease and erect
warning signs to alert motorists to the occurrence of quokkas.
 Train Alcoa staff and consultants in accurate identification of quokkas and
their preferred habitat, to increase reliability of sighting records on Alcoa’s
‘Fauna Sighting Record Sheet’.
 Liaise with DEC to organise an Alcoa representative on and subsequent
contribution to the quokka recovery team.
33
3. BAUDIN’S BLACK COCKATOO (Calyptorhynchus baudinii) and FOREST
RED-TAILED BLACK COCKATOO (Calyptorhynchus banksii naso)
Baudin’s black cockatoo, also known as the white-tailed black cockatoo or long-billed
black cockatoo, and the Forest Red-tailed black cockatoo are both endemic to the
south-west of Western Australia. The total population of Baudin's cockatoo is
estimated to be 10 000 to 15 000 birds (Higgins 1999). The current population of
Forest Red-tailed black cockatoos is also estimated to be approximately 15 000 birds
based on surveys and observations (Abbott 1998a; Johnstone & Kirkby 1999). Both
black cockatoo species are given special protection under Western Australia's Wildlife
Conservation Act 1950 and are listed as "Declared Threatened Fauna: Schedule 1 Fauna that is rare or is likely to become extinct". Both species are also listed as
Vulnerable under the Commonwealth Environment Protection and Biodiversity
Conservation (EPBC) Act 1999. The Forest Red-tailed black cockatoo has only
recently been listed in 2009. Baudin’s black cockatoo has an additional ranking under
World Conservation Union criteria of “Endangered” due to a “continuing decline,
observed, projected, or inferred, in numbers of mature individuals” and because only
10% of individuals make up the breeding population (IUCN 2007). The Forest Redtail is given a status of “Least Concern” (IUCN 2007). BirdLife International 2007
also lists Baudin’s cockatoo as Endangered (BirdLife International 2007).
Carnaby’s black cockatoo (Calyptorhynchus latirostris) is another species of black
cockatoo that uses the northern jarrah forest but this species is only a transitory user of
the forest, spending most time on the swan coastal plain and in the wheatbelt and
stopping to feed in the jarrah forest as it moves between the two. Like the other two
species Carnaby’s is listed under both state and federal legislation (listed as
endangered). This species is not specifically addressed in this management plan, but
threats to this species are similar to those of the other two species and recommended
actions will equally benefit Carnaby’s black cockatoo.
There are five species of cockatoos of the genus Calyptorhynchus endemic to
Australia (Cale 2003). Baudin’s Cockatoo Calyptorhynchus baudinii was named in
honour of the French commander Captain Thomas Nicolas Baudin (1754-1803) by
Lear in 1832 (Ackermann and Lear 1832). There are two species of white-tailed black
cockatoo in south-west Western Australia that are closely related, the long-billed
Baudin’s cockatoo and the short-billed Carnaby’s cockatoo (Calyptorhynchus
latirostris). The cockatoos were initially recognised as two subspecies of C. baudinii
(Serventy and Whittell 1948; Saunders 1974) until Johnstone and Storr (1985)
34
classified them as separate species. Given the mobility of the birds and the continuity
of the forest habitat, it is unlikely that discrete sub-populations of the two species
occur (DEWR 2007). The two species are very similar in appearance and can be
difficult to distinguish. The main difference is the upper mandible, which on Baudin’s
cockatoo is longer and finer at the tip compared with Carnaby’s cockatoo. Baudin’s
cockatoo also has a wider and higher adult skull compared to Carnaby’s cockatoo
(Saunders 1974). The two species also differ in their distribution, calls, and feeding
behaviour. Baudin’s cockatoo has a wide range of calls including a distinctive,
shortened whistle ‘we-ow’, in contrast to the Carnaby’s longer drawn-out ‘whee-loo’
call (Chapman and Massam 2005). When feeding on marri nuts, Baudin’s cockatoo
pulls the seeds out of the fruit with its long culmen, doing very little damage to the
rim of the capsule, while Carnaby’s cockatoo breaks the rim open with its shorter
culmen to access the seed (Saunders 1974).
Baudin’s cockatoo is a large cockatoo 50-60 cm in length, with a wingspan of 110 cm
and weight of 560-770 g (Johnstone and Storr 1998). The adults are mostly brownish
black with feathers edged with dusky white giving a scalloped appearance. They have
large, rounded patches (white to yellowish-white in the female and dusky-white to
brownish-white in the male) on the ear coverts, and rectangular white panels on the
inside of the tail (Fig. 8). This species has a large bill (with a very elongate upper
mandible) that is black on the male and whitish-grey with a black tip on the female; a
dark brown iris surrounded by a reddish-pink eye-ring on the male and a grey eye-ring
on the female; a short, rounded, erectile crest; and grey feet (Higgins 1999; Johnstone
and Storr 1998). Juvenile birds are like the adults in appearance, but with a grey
instead of white patch on the ear coverts. The bill of the juvenile male is like that of
the adult female and begins to darken after the second year (Johnstone and Storr
1998).
There are three sub-species of the red-tailed black cockatoo in Western Australia and
they vary in size, colouring and distribution. The Forest Red-tailed black cockatoo
(Calyptorhynchus banksii naso) is slightly larger, with a heavier bill and a more
brightly coloured female than the inland red-tailed black cockatoo (C. b. samueli). The
northern red-tailed black cockatoo (C. b. macrorhynchus) is similar in appearance to
the forest sub-species, but has longer wings, a larger bill and the female's tail is barred
with yellow, not red. They were all originally named Psittacus banksii from a
specimen collected at Endeavour River in Queensland (Higgins 1999). The south-west
subspecies, Calyptorynchus banksii naso, was first recognised and described by Gould
in 1836 (1836).
35
Fig. 8. Baudin’s black cockatoo: male (left) and female (right) (Johnstone and Storr 1998).
The Forest Red-tailed black cockatoo (C. banksii naso) is 55–60 cm in length and
570–870 g in weight (Higgins 1999). Male and female birds are mostly glossy black
with a pair of black central tail feathers, a crest, robust bill and bright red or orange
barring in the tail (Higgins 1999). Males have a dark brown iris, dark grey eye-ring,
broad red tail panels and black legs. The female is distinguished by yellow spots on
the feathers of the head and upper wing coverts, yellow or orange barring on the tips
of the feathers of the throat, breast, belly and under-tail coverts and a light grey bill
with a dark grey tip (Johnstone & Storr 1998) (Fig. 9). Their tail feathers are bright
red and orange, grading to yellow on the inner margins.
The juvenile is similar to the adult female but has a white eye-ring (Higgins 1999;
Johnstone & Storr 1998). Their cry is a loud 'Karee' or 'Krar-raak' (Johnstone & Storr
1998).
36
Fig. 9. Female Forest Red-tailed black cockatoo (photo by Tony Kirkby).
3.3.1 Lifespan and breeding
Individuals of both species have a lifespan of 25-50 years, begin breeding at four years
of age, and are monogamous with pairs generally mating for life (Smith and Saunders
1986; Sindel and Lynn 1989; Johnstone 1999). Baudin’s black cockatoos breed in late
winter and spring, from August to December (Gould 1972; Saunders 1974; Saunders
et al. 1985; Johnstone 1997). Adults nest in solitary pairs and usually in the same
hollow each breeding season. Prior to the eggs being laid, males have been observed
to bring pine and Banksia cones to the nest, which the female chews up to make a nest
base (Bohner 1984). Females usually lay two eggs, but generally only one egg is
incubated and fledged at 28 days. The female rears the chick, leaving the nest to feed
and returning daily to feed the chick. The chick remains in the nest for up to 16 weeks
(Bohner 1984) and even after it has left the nest the young bird is fed for up to 18
months by the female (R. Johnstone, pers. comm.). The cockatoos seen today are part
of an ageing population with little recruitment. The interval between generations is
thought to be seven years (Storr 1991) and adults generally breed every second season.
Breeding success is estimated at only 0.6 per pair (Johnstone and Storr 1998). Only
around 10% of the population breeds each year, and in years where marri seed
production is poor the birds may fail to raise any young at all (Chapman and Massam
2005).
37
Baudin's cockatoo is usually seen in groups of three (comprising the adult pair and a
single dependent young) or in small flocks of up to 50 birds, but will occasionally
gather in large flocks of up to 300 birds during the non-breeding season, usually at
sites where food is abundant (Higgins 1999; Storr 1991).
Forest Red-tailed black cockatoos breed in October and November each year and
sometimes in March and April in years with good autumn rainfall (Johnstone 1997).
One or sometimes two eggs are laid, but only one chick fledges (Johnstone and Storr
1998). The female incubates the egg and during the incubation period (29-31 days) the
male feeds with the flock and flies back to the nest to feed the female and chick once
or twice a day (Johnstone and Kirkby 1999). The young are fed by the parents for 3–4
months after fledging (Lendon 1979; Sindel and Lynn 1989) and juvenile birds may
take up to a year to learn how to extract seed from marri fruits, during which time they
are fed by both parents (Johnstone and Kirkby 1999). Similar to Baudin’s, it is
estimated that less than 10% of the forest red-tailed population are capable of breeding
in any one year and birds may only breed every 2–3 years (Johnstone and Kirkby
2005). Data collected in 2007 suggests that breeding success for the sub-species is low
because from 60 nests that were monitored, only one pair raised a chick successfully
(R. E. Johnstone 2008, pers. comm).
Flocks of up to 50 individuals spend the night roosting in trees and leave at sunrise,
splitting into smaller family groups, of around 10 birds, and moving into adjacent
forest (Abbott 1998b). After a short period of preening and basking in the sunlight
they feed for 10–12 hours before moving off to creeks or dams to drink. On dark, they
return to their roosts (Johnstone and Kirkby 1999).
3.3.2 Diet
In forest areas, Baudin’s cockatoo feed mainly in the canopy on seed and flowers of
marri (Corymbia calophylla) trees, which comprises 80% of their diet (R. Johnstone
pers. com.). They have also been observed to eat jarrah (Eucalyptus marginata)
seeds, and Proteaceous species such as Banksia, Hakea and Persoonia (Saunders
1974; Wilcox 2005). Marri flowers during February and March, although old trees
may carry blossoms up to July or August (Robinson 1960). A heavy crop of blossom
in one year is generally followed by very little the following year. Baudin’s cockatoo
can consume large quantities of honey from the marri blossom (Robinson 1960). In
general, there is a good crop of marri seed every three years (Mawson 1995), although
with changes in rainfall in the south-west of Australia, seed production has been
inconsistent in recent years. Each fruit develops up to three seeds in a tough protective
woody casing, and the cockatoos spend significant effort extracting the seeds.
Although marri seeds take longer to extract than other available foods, the return of
energy per unit of foraging time is high (Cooper et al. 2002). As soon as the marri
fruit has reached a stage where the seeds have developed, the cockatoo will attack it,
38
even if immature, dropping the fruit if it is unsatisfactory. Baudin’s cockatoo show a
preference for certain marri trees for feeding (“feed trees”), leaving adjacent marri
trees and fruit untouched (“non-feed trees”). Birds occasionally forage on the ground,
taking seed from fallen fruits, and extracting insect larvae from beneath the bark of
fallen trees (Saunders 1979). They also strip bark from dead trees in search of insects,
mainly beetle and borer larvae. Feeding generally occurs in the morning between 0730
and 1000 (Cooper 2000).
Baudin’s cockatoo have also been observed to feed on seeds of apples (particularly
red-skinned varieties), pears and grapes from orchards when the natural food source is
scarce. Heavy marri blossom means less trouble from cockatoos in the orchards
(Robinson 1960). Cockatoos are very adaptable at exploiting new foods in a changing
environment. In a study on captive cockatoos, they were able to remove seeds from
all food items offered even if they are very rarely or never used as a food source in the
wild (Cooper 2000). They have also been observed eating seeds of Pinus species in
Kelmscott and Bottlebrush on the Swan Coastal Plain in Armadale and Kelmscott
(Robinson 1960; Johnstone 2005).
Baudin’s cockatoo has a powerful bill that enables them to extract seeds from woody
capsules of native trees. When feeding on marri nuts, the cockatoo removes seeds
from their capsules by inserting its upper mandible into the capsule and then hooking
and pulling the seed out (Cooper 2000; Saunders 1974). Seeds are taken from apples
and pears by using the long culmen to push in along the stem and hook the seeds out
through the entry hole the same way that marri fruit are attacked, leaving the fruit
dropped and undamaged or split in two (Saunders 1974; Higgins 1999).
Around 90% of the diet of the Forest Red-tailed black cockatoo is made up of the
seeds from marri and jarrah fruits (Johnstone and Kirkby 1999). Other species they
feed on include blackbutt (E. patens), Albany blackbutt (E. staeri), sheoak
(Allocasuarina fraseriana), Snottygobble (Persoonia longifolia) and the nonindigenous native spotted gum (E. maculata) and Cape Lilac (Johnstone and Kirkby
1999; Johnstone and Storr 1998). A detailed study of the feeding behaviour of the
Forest Red-tailed black cockatoo at Bungendore Park and Jarrahdale between 1996
and 1999 revealed that birds feed on marri throughout the year but switch to jarrah
and other foods in March and June when marri fruits are less abundant (Johnstone and
Kirkby 1999). Birds also appeared to return daily to individual trees to feed, until the
supply of fruit was exhausted (Johnstone and Kirkby 1999). Additionally birds appear
to select marri trees with nuts that contain high seed numbers and high seed weight
(Cooper et al. 2003). Given that marri trees take three years to recover a high fruit
yield, birds must assess the seed yield of the fruits from individual trees each year they
fruit. The method by which birds determine which trees have the highest seed yield is
unclear (Cooper et al. 2003).
39
Baudin’s cockatoo are found in temperate forests and woodlands dominated by the
eucalypts jarrah, marri and karri in the extreme south-west of Western Australia (Fig.
10). The range of the species, which is generally bounded by the 750 mm isohyet,
extends from Albany northward to Gidgegannup and Mundaring (east of Perth), and
inland to the Stirling Ranges and near Boyup Brook (Davies 1966; Saunders 1974,
1979; Saunders et al. 1985; Storr 1991). The extent of occurrence is estimated at
40,000 km2, while the area of occupancy is estimated at 2,000 km2 (Garnett and
Crowley 2000). Area of occupancy can vary substantially between the breeding and
non-breeding seasons. Breeding is generally in the far south of the range, in an area
extending from Nornalup northward to near Bridgetown, or sometimes further north
to Lowden and Harvey (Higgins 1999; Saunders 1979; Storr 1991). Breeding adults
probably return to the same nesting areas each year (Saunders 1979). At the end of the
breeding season, birds move in response to changing food resources and can move to
the central and northern Darling Range and the eastern margin of the Swan Coastal
Plain (Johnstone and Storr 1998). Baudin’s cockatoo occurs as a single, contiguous
population and has disappeared from 50% of its range over the past 50 years (Garnett
and Crowley 2000).
Baundin’s cockatoos nest in hollows in mature karri (Eucalyptus diversicolor), jarrah,
marri and wandoo (E. wandoo) trees, with the average age of nest trees calculated as
233 years (Johnstone 2003). Some nest trees have been estimated to be between 300500 years of age. The birds have an association with very large diameter (>1.5 m)
marri trees (BirdLife International 2005). Baudin’s cockatoo requires a tree hollow of
at least 30-40 cm diameter at the base and more than 30 cm deep (Saunders 1974;
Saunders et al. 1982). Hollow formation in south-western hardwoods, such as jarrah,
marri, karri, wandoo, tuart (E. gomphocephala) and salmon gum (E. salmonophloia),
is a very slow process relying on a myriad of fungi and invertebrates such as termites
to decompose and excavate the heartwood. Hollows generally only appear when a
branch or top of the main trunk snaps off, or the tree is damaged by fire. Hollow
entrances are more common in larger stems and branches because damage is less
likely to be occluded by growth of external sapwood (Marks et al. 1986). This
extremely slow process, combined with the fact that hardwoods live up to 500 years,
means that hollows can be quickly lost but not easily replaced.
40
Fig. 10. Distribution map of Baudin’s cockatoo (Chapman and Massam 2005).
The Forest Red-tailed black cockatoo only occurs in the south west of Western
Australia, mainly in the hilly forests of the Darling Range and in the same habitats as
Baudin’s cockatoo. They largely inhabit jarrah, karri and marri forests receiving more
than 600 mm average rainfall annually (Saunders et al. 1985; Saunders and Ingram
1995) but are also known to use wandoo woodland mixed with jarrah and marri (WA
CALM 2006). Habitat in which the Forest Red-tailed black cockatoo occurs at
Bungendore Park and Jarrahdale, have an understorey of Bull banksia (Banksia
grandis), Snottygobble, sheoak and Dryandra spp., with scattered blackbutt and
wandoo (Johnstone and Kirkby 1999).
The Forest Red-tailed black cockatoo has declined in range by 25–30% as a result of
clearing of the margins of the forests for agriculture in the early 1900s (Mawson and
Johnstone 1997). The former distribution in the 1900s, was around 80 843 km² and
the current distribution is approximately 52 198 km². There is no data available on the
area of occupancy of the Forest Red-tailed black cockatoo however it is likely to be
less than the extent of occurrence (WA CALM 2006). Formerly they occurred from
Albany to as far north along the Swan Coastal Plain as Dandaragan and east to
Toodyay, Wandering and Kojonup (Johnstone 1997). Presently they occur as far north
as Perth and east to Mount Helena, Christmas Tree Well, North Banister, Mt
Saddleback, Rocky Gully and the upper King River (Johnstone 1997) (Fig. 11). Now
41
they are rare on the Swan Coastal Plain except for small isolated breeding populations
and movement of birds into the area to feed during the fruiting season of Cape Lilac
(Melia azederach) (Stranger 1997; WA CALM 2006).
The Forest Red-tailed black cockatoo is unlikely to have a fragmented population
because they are highly mobile birds and they inhabit vegetation that is fairly
continuous due to the connectivity of the state forest timber reserves. The birds have a
predicted home range of about 116-187 ha (Abbott 2001). However, there are several
small isolated populations on the Swan Coastal Plain and in some eastern parts of its
range (WA CALM 2006).
Similar to Baudin's Cockatoo, the Forest Red-tailed black cockatoo nests in large
hollows of marri, jarrah and karri (Johnstone and Kirkby 1999). They have also been
sighted nesting in wandoo and bullich (E. megacarpa) (WA CALM 2006). The
species has a particularly strong association with nesting in very large (greater than
1.5m diameter) and old (230-300 years) marri trees (pers. comm. T. Kirkby).
Fig. 11. Distribution map of the three sub-species of Forest Red-tailed Black Cockatoo
(modified from Johnstone and Storr 1998).
42
3.5 Key threats
The population status of Baudin’s and Forest Red-tailed black cockatoos is of
increasing concern because of the seemingly dramatic decline in numbers in recent
years with their range contraction. Conservation of these species requires reducing
their major threats: loss of feeding and breeding habitat, illegal shooting by
orchardists and the competitive impact of the feral European bee (Johnstone 2005).
3.5.1 Habitat loss
Loss of habitat, in particular eucalypt forests and woodlands, has dramatically reduced
the range occupied by black cockatoos. Over the past century, almost 90% of the
original vegetation has been cleared for agriculture, meat production, dairy farming,
hobby farms, orchards, vineyards, pine plantations, bauxite and other mining, timber
and wood chipping, cities and towns. Habitat loss and degradation also occurs from
indirect sources such as climate change and dieback due to the soil-borne pathogen
Phytophthora cinnamomi. At present, extensive tracts of uncleared land only remain
in the larger nature reserves and forest reserves and even these are disturbed to varying
degrees. These changes across the landscape have greatly affected the distribution and
the prospects for future persistence of Baudin’s cockatoo and the Forest Red-tailed
black cockatoo because they have resulted in mass loss of feeding and nesting trees
(Johnstone 2005).
Veteran trees (over 200 years of age) and stag trees (ancient dead trees) are critical for
the long-term survival of black cockatoos, particularly marri, jarrah, karri, salmon
gum and white gum trees. In many forest areas, these age classes of tree are missing
because of historical logging in the forests in the south-west of Western Australia and
continued selective thinning of mature trees for sawlog production. This has led to a
lack of trees with suitable hollows in forest sites, and cockatoos have to compete
among themselves and with other species for available hollows. Black cockatoos are
highly dependent on hollows for breeding and require hollows of a size that is
relatively rare in the jarrah forest (Whitford and Stoneman 2004).
Continued loss of forest to mining in some areas is also an issue, since revegetation
will have no impact on conservation outcomes within the lifespan of this species. The
rate of hollow formation depends on the species of tree, its location and history but in
general more than 100 years are needed for hollow development (Hussey 1997).
3.5.2 Changing fire regimes
Changes in fire regimes over time have also had an impact on available nest sites and
food resources for black cockatoos. Intense wildfires can fell large old trees and lead
to loss of suitable habitat by destroying tree canopies and nest hollows. Hollowingout of the butt of the tree by fire and subsequent breakage of the tree is the most
43
frequent cause of tree fall (Whitford and Stoneman 2004). Fires that reach the tree
canopy also remove the food source for a couple of years until the trees re-sprout and
produce another flower crop.
3.5.3 Competition for nest hollows
The European honey bee (Apis mellifera) is a major threat to the future conservation
of Baudin’s cockatoo and the Forest Red-tailed black cockatoo. The bee is an exotic
species that was introduced to Australia over 170 years ago. In the past ten years the
honey bee has invaded native vegetation from the original hives kept for commercial
honey production, and has become a feral pest. It is thought that the increase in canola
production has provided a high-energy diet that has led to the bee population
explosion. In addition, the warming climate of the region has allowed the bees to
extend their range of occupancy. The bees compete for hollows with black cockatoos,
forming long-term hives in the nests. In some cases, the bees invade occupied hollows
and can kill the young developing chick with bee stings. Around 20% of hollows used
by Baudin’s cockatoos in research study areas have been taken by bees (Johnstone
2003). In some trees there are up to six bee hives and in a survey of 3-4 km of
creekline in the Wungong catchment, 175 bee hives were recorded (Water
Corporation 2007).
The rapid expansion of some native species in response to landscape changes, and the
introduction of some exotic pest species have also proved a threat. Galahs (Cacatua
roseicapilla) and corellas (Caacatua spp.) have extended their range because the
removal of woodland and the spread of agriculture have provided more of their
preferred grassland habitat (Jupp 2000). These species remove eggs and chicks of
Baudin’s cockatoo from hollows or kill chicks in the hollows. The expansion of the
Australian Wood Duck (Chenonetta jubatta) and Australian Shelduck has also
resulted in hollow competition. Possums have also been noted eating eggs and chicks
of Baudin’s cockatoo.
3.5.4 Shooting by orchardists
The cockatoos damage commercial apple and pear orchards by severing fruit from
trees and extracting the seeds. They may also damage branches of fruit trees by
chewing. Shooting by orchardists has been illegal since 1996 but still occurs despite
heavy penalties.
3.5.5 Poaching of chicks and eggs from the wild
Black cockatoos are a desirable bird in the illegal wildlife trade and chicks and eggs
have sold for high prices locally or overseas on the black market after being poached
from the wild. Compared to other native black cockatoos, Baudin’s cockatoo is
44
relatively difficult to poach from the wild as the nests are 30-50 m above the ground
and difficult to reach (Jupp 2000).
Conserving feeding, roosting and nesting habitat is a priority for management of
habitat required by black cockatoos. For mining operations, retaining habitat trees at
an individual level is generally not possible as it is for silvicultural operations,
therefore areas of importance along stream zones and in unmined forest need to be
identified and protected.
Alcoa undertakes pre-mining fauna surveys before entering a new mining region and
fauna surveys are conducted at proposed haul road stream crossings to identify forest
areas with rare or protected species and high value habitat trees. These surveys
provide opportunity to protect habitat trees, roost sites and potential nest sites. For
haul road crossings through CAR reserve (stream zones) a report with
recommendations (including recommendations based on fauna surveys) of the
suitability of the haul road alignment is given to Alcoa and the Mining Operations
Group (MOG - a group comprised of representatives from various government
organisations) for review. The clearing of sections of CAR reserves is strictly
controlled. Alcoa endeavours to avoid identified habitat trees with hollows and may
re-align haul roads accordingly.
Alcoa does not mine old growth forest within its lease, therefore preserving virgin
jarrah and marri trees with good potential for hollows that were not logged during
early European settlement of the region. The number of hollows borne by jarrah and
marri trees increases as the size and age of the tree increases, and trees with large
crowns bear more hollows than trees with small crowns (Whitford and Stoneman
2004). Only three hectares of old growth forest has been identified within Alcoa’s
current mining regions and these have been protected from adjacent clearing with a
100 m buffer zone of vegetation. Trees were injected with phosphite in August 2007
to improve protection against dieback.
Sightings of black cockatoos within Alcoa’s mine lease that are recorded as part of the
‘Fauna sighting’ system are collated and given to the Western Australian Museum to
add to their species distribution database. During Alcoa’s long-term fauna monitoring
survey in 2006, Baudin’s cockatoo and Forest Red-tailed black cockatoos were
recorded at Jarrahdale, Karnet and Huntly (EMRC 2006).
45
Implementation of prescribed burns to reduce forest fuel loads will help avoid the
devastating effects of summer wildfires and the potential loss of nest and roost trees.
Alcoa develops annual and rolling five year burn plans in conjunction with DEC for
forest within its mining areas. Forest is burnt on an 8-15 year rotation to reduce fuel
loads and the likelihood of an area carrying an intense wildfire. Rehabilitated sites are
generally burnt in spring after 12-15 years of age because research has shown that low
to moderate intensity burns at this time are beneficial for the successional
development of rehabilitated areas.
3.6.3 Regeneration of native vegetation
Eucalypt regeneration is urgently required because veteran and stag trees are in serious
decline in many areas, especially farmlands, with very few seedlings being recruited.
Habitat enhancement through the creation of native corridors and the protection of
remnant bushland with large trees will help preserve habitat for black cockatoos.
Alcoa has been a major sponsor of the Swan-Alcoa Landcare Program (SALP) for the
past 10 years, providing funds for community groups involved in on-ground
revegetation and rehabilitation projects within the Swan and Canning catchments.
Alcoa provided $750,000 over three years (2007-2009) to the program. Projects
involve linking existing native vegetation corridors, enhancing remnant native
vegetation with weed control and in-fill planting, and planting tree shelter belts on
farm properties.
Alcoa made a commitment under the revised Wagerup Environmental Review and
Management Program (ERMP) in 1978 to rehabilitate dieback affected areas adjacent
to its mining operations, irrespective of the cause of the infection. The aim of the
program, known as dieback forest rehabilitation (DFR), is to improve forest value by
re-establishing forest structure and biomass at severely degraded sites. Disturbance of
the existing vegetation is minimised and old stag trees which may provide nest sites
for cockatoos are left standing. Large dead trees are just as likely as live trees to bear
potentially usable hollows and it has been found that 65% of all potentially usable
hollows are in dead wood (Whitford and Stoneman 2004). Each year, Alcoa commits
up to $300,000 to DEC to undertake the on-ground operations. Affected forest is
planted with jarrah and marri seedlings and seeded with a legume understorey mix.
Alcoa also has a research program in collaboration with DEC that aims to maximise
tree establishment on severely impacted DFR sites as they are often harsh
environments for plant growth.
46
3.6.4 Artificial nest boxes
Where old, hollow trees no longer exist, artificial nest boxes may facilitate the
cockatoo’s to return to the area to nest. The appropriate sized entrance hole for a nest
box for black cockatoos is 25 cm diameter (Hussey 1997). PVC tubes with a top entry
hole, wooden ladder down the side and sacrificial chewing timber blocks inside are
attached to trees to provide artificial nest sites (Hussey 1997). Feral bees don’t appear
to like the PVC as a nest material, and competitor birds, such as the corella, prefer a
bottom entry hollow. Alcoa has trialled nest boxes in rehabilitated sites in the past,
but these were not designed for the requirements of black cockatoos.
3.6.5 Feral bee eradication
The WA Museum is documenting the location of feral bee hives during field
monitoring of black cockatoo nest sites. They record hive locations, what species of
tree they are found in, and the number of hives in each tree. The WA Museum
continues to research effective methods of feral bee eradication and control as no
successful method of permanent hive removal has been identified to date. Once the
bees in a hive have been killed, it takes around 18 months for the hive to decay and be
cleaned out by birds so the hollow can be used again (R. Johnstone, pers. com.).
3.6.6 Community awareness
The black cockatoos of the south-west forests are popular and eye-catching species
due to their large size, colouration, cheeky nature and distinctive calls. As such, they
receive special attention from the public and a lot of interest has been shown in
conservation initiatives. Raising awareness in the community is important so local
landholders know the endangered status of the birds and the importance of
maintaining existing nest hollows (especially veteran and stage trees) and feeding
habitats. The Western Australian Museum and the Water Corporation has operated the
‘Cockatoo Care Program’ since 2001 that encourages community awareness and
conservation of the birds, including raising awareness among orchardists of the
protected status of Baudin’s cockatoo and that shooting is illegal. They provide
advice on non-lethal methods for managing cockatoo damage in orchards such as
exclusion netting and methods of scaring the birds from the orchards.
Western Australian Museum
A joint initiative between the Western Australian Museum, the Water Corporation and
the Tourist Commission involves ongoing research that is monitoring nests of
Baudin’s cockatoo throughout the southern jarrah forests and nests of Red-tailed black
cockatoos within the Wungong catchment. Other State and local government
47
departments are also involved, including Bungendore Park Management Committee
and Serpentine-Jarrahdale LCDC. The aim of the research is to gain knowledge of the
cockatoos breeding biology (including clutch size, incubation period, fledging period,
and timing of nest attempts), nest areas, nest trees, and breeding behaviour. This
information is vital for ensuring the survival and recovery of cockatoo populations.
Feeding and distribution is also recorded at many locations in the south-west,
including Mundaring, Armadale, Kelmscott, Wungong, North Dandalup, Pinjarra,
Serpentine Hills, Samson Brook, Collie, Nannup, Manjimup and Walpole. Winter or
non-breeding roosts of Baudin’s cockatoo were monitored at Mundaring, Stoneville,
Carmel, Wungong and Araluen during 2005. In 2006-07, the field program was
expanded with greater emphasis on finding nest sites of the species and controlling
feral bees.
Alcoa of Australia
Alcoa recently supported a three year (2006 – 2008) collaborative research programme
with Edith Cowan University (ECU) and DEC to study Baudin’s cockatoo, Forest
Red-tailed black cockatoo and Carnaby’s cockatoo. The aim of the study was to
establish which landscape elements affect the distribution of cockatoos and identify
factors affecting the likelihood of Baudin’s cockatoo’s feeding in orchards (Weerheim
2008). The study also investigated if post-mining rehabilitated sites are used by
cockatoos.
Most records of Baudin’s cockatoos were in areas of the landscape associated with
orchards, including forest adjacent to orchards, orchards themselves and surrounding
paddocks. They were recorded infrequently in continuous jarrah forest (Karnet) or
previously mined and rehabilitated forest (Wungong). Sightings within the Wungong
area were always associated with small blocks of pine trees or creeks within mature
unmined forest, leading to the conclusion that they are unlikely to utilise rehabilitated
forest, either pre-1988, when pines and eastern state eucalypts were planted, or post1988 rehabilitation of jarrah and marri. While individuals were never observed
feeding on apples in the orchards (92% of recorded diet was marri seeds), their strong
association with parts of the landscape containing apple orchards and their seasonal
movements into the area when apples were ready for harvesting, suggests apples are
an important food source for Baudin’s cockatoos in combination with marri seeds.
Orchardists reported flocks of cockatoos feeding on apples in the orchards at sunrise
and feeding behaviour at this time of day was not measured as part of the study, likely
resulting in under-representation of the use of apples as a food source by this species.
The study supported others (e.g. Higgins 1999) in showing that the majority of
Baudin’s cockatoos do not breed in the northern jarrah forest, with significant
movement of birds into the area during the non-breeding season. In contrast, the
Forest Red-tailed black cockatoos were found to occur in high numbers year round in
both unmined jarrah forest and mined areas. They were never recorded in young
48
rehabilitation less than 6 years old. As shown in previous studies, birds appeared to
selectively feed on particular marri trees. The study was only conducted over one year
and relative use of components of the landscape may change from year to year in
response to changes in resource availability.
3.7 Recommendations
The following actions are recommended for managing black cockatoos within Alcoa’s
mining lease:
 Incorporate expert surveys of black cockatoo nest and roost sites along
proposed haul road alignments into pre-mining fauna surveys. Map areas of
critical habitat on Alcoa’s GIS for use in informing infrastructure
planning/development.
 Investigate, trial and test the value of feasible options for return of tree hollows
or alternatives (e.g. artificial nest boxes) as nesting habitat for black cockatoos
to replace tree hollows lost due to forest clearing.
 Use research and monitoring data to develop predictive models for identifying
high conservation value feeding and breeding habitat for black cockatoos in
Alcoa's mine lease.
 Research and compare feeding rates of black cockatoos in rehabilitation and
unmined forest (using feeding residues) to determine the value of
rehabilitation as feeding habitat for black cockatoos.
 Develop methods through research to improve the health and survival of
veteran marri and jarrah trees to conserve tree hollows, and roost and feed
trees. One possibility is to expand the DFR program to include protection of
veteran trees on dieback affected sites through use of phosphite plugs for
jarrah and nutrient plugs for marri.
 Research the impacts of tree thinning in rehabilitation on tree development,
particularly: fruit/seed yield as food for black cockatoos; and crown and
hollow development as roost and nest habitat.
 Contribute funding to research into feral bee management/eradication.
 Raise awareness of Baudin's cockatoo status among local neighbouring
orchardists and promote non-lethal control methods.
 Provide resources/support to the Black Cockatoo Rescue Centre through action
grants and donations.
49
4. NOISY SCRUB-BIRD (Atrichornis clamosus)
The Noisy Scrub-bird (Atrichornis clamosus) is given special protection under
Western Australia's Wildlife Conservation Act 1950. It is listed as "Declared
Threatened Fauna: Schedule 1 - Fauna that is rare or is likely to become extinct". It is
also listed as Vulnerable under the Commonwealth Environment Protection and
Biodiversity Conservation (EPBC) Act 1999. It has a ranking under World
Conservation Union criteria of “Vulnerable D2: population very small or restricted to
number fewer than 1000 mature individuals, and population with a very restricted area
of occupancy (typically less than 20 km2) or number of locations (typically five or
fewer) such that it is prone to the effects of human activities or stochastic events
within a very short time period in an uncertain future, and is thus capable of becoming
Critically Endangered or even Extinct in a very short time period” (IUCN 2007).
BirdLife International 2007 lists the species as Vulnerable (BirdLife International
2007).
The Noisy Scrub-bird (Atrichornis clamosus Gould 1844) is from the small endemic
monogeneric family of song birds, the Atrichornithidae. There is only one other
species in this family in Australia, the Rufous Scrub-bird, A. rufenscens which lives in
the rainforests of northern New South Wales and southern Queensland (Portelli 2004).
Phylogenetic analysis has shown the Atrichornis genus is sister to the Menura genus
(the lyre-birds), and these two taxa are closely related (Chesser and ten Have 2007).
The Noisy Scrub-bird was first discovered at Drakes Brook in the Darling Range of
Western Australia in 1842 by pioneer naturalist John Gilbert.
The Noisy Scrub-bird is a small finely-barred brown bird about 20 cm long (of which
10 cm is tail) with a strong pointed bill, powerful legs, graduated tail and short round
wings (Fig. 12; Danks et al. 1996). The males have a white throat, black upper breast
and buff-brown abdomen. The female lacks the black breast marking (Slater 1974).
The upper mandible of the bill is reddish-brown, while the lower mandible and the
legs are pinkish-white (Slater 1974). The dorsal and ventral feathers are extremely
dense (Bock and Clench 1985). Females have a mean weight of 34.6 g while males
are larger and have a mean weight of 51.8 g (Danks et al. 1996). Chicks have a dense
line of grey down from the crown to the rump, with small thin patches on the
shoulders and thighs. Fledglings have a plumage similar to that of the female but with
bright rufous patches on the forehead, chin and throat (Bock and Clench 1985).
Juveniles obtain a full adult plumage in their second year.
50
Fig. 12. The Noisy Scrub-bird (Atrichornis clamosus) (Chapman 2007).
Noisy Scrub-birds are semi-flightless and can fly for only a few metres. They have
reduced appendages compared with many other passerine groups, and these
modifications are associated with the reduction of flight and increased terrestrial
movement (Raikow 1985). They use their short wings frequently to assist with
moving through thick vegetation and also to climb up small shrubs and leap from one
bush to another.
The males have a territorial song that easily distinguishes the Noisy Scrub-bird from
other birds, while the females do not sing but give alarm calls only. The male songs
are powerful, ringing and metallic, with a ventriloquil quality. The songs are
exceedingly loud and shrill and “produce a ringing sensation in the ears” (Robinson
and Smith 1976). Territorial males sing throughout the year, however the song output
increases in April, reaches a peak in May to June and begins to decrease in October
(Smith and Forrester 1981). Maximum song output is in the two to three hours after
sunrise (Smith and Robinson 1976). The vocalisation is used for counter-singing
interactions between neighbouring males (Portelli 2004). The song has a role in
territorial defence, and may play a role in attracting females during the breeding
season (Portelli 2004). The territorial song of the male can be accompanied by a tail
display, where the tail assumes a wide fan-shape and is drawn up over the back. The
territorial song comprises a number of phrases. During a bout of singing, individual
males alternate the song types in their repertoires and rarely repeat the same song type
in succession (Portelli 2004). Generally, a bird sings his full repertoire after singing a
51
relatively small number of songs (i.e. 20), typically within a single bout of singing
(Portelli 2004). Noisy scrub-birds are capable of mimicry but very rarely use it
(Robinson and Smith 1976). Males start giving a full territorial song in their second
year.
4.3.1 Lifespan and breeding
The lifespan of the Noisy Scrub-bird is 10 years in captivity and indeterminate in the
wild (Danks et al. 1996). The social behaviour and organisation of the Noisy Scrubbird, particularly its social mating system, is poorly known (Portelli 2004). Noisy
scrub-birds are usually monogamous (Smith and Robinson 1976) although males may
be opportunistically polygamous (Danks et al. 1996). The breeding season extends
from April to October (Smith and Robinson 1976). Females begin breeding when one
year old, while males first breed when at two to three years of age (Danks et al. 1996).
The female occupies a small nesting area at the edge of the male’s territory and the
male rarely visits this area. The female tends to build the nest in the same area year
after year, often within five metres of the previous year’s nest (Smith and Robinson
1976). The nest takes between two to three weeks to build, can be up to 18 cm in
diameter and is made with pliable broad-leafed sedges such as Lepiosperma species
on the inside and leaves of Agonis and Eucalypt species on the outside. The nest is
dome-shaped with a small side entrance. Nests are usually built close to the ground in
a clump of rushes or tangle of shrubs, which support the nest. The nest is lined with a
cardboard-like substance from rotten wood (Danks et al. 1996). The female will wait
for around a week after the nest is completed before laying an egg to allow the lining
to firm and the nest to remain damp but not wet. Eggs are laid from late May to early
September with peaks in late June and late August (Smith and Robinson 1976). If the
egg is lost the female may build another nest and re-lay. Eggs are an average size of
28.5 x 19.8 mm and have a dull, pale buff surface with blotches of orange brown
(Smith and Robinson 1976). Eggs are incubated for around 30-40 days. Nest
sanitation is maintained by the female, who removes the faecal sacs and deposits them
in a stream or bush away from the nest (Smith and Calver 1984). The nestling fledges
when three to four weeks old around late October. The chick may stay with the female
for some time after fledging, with chicks having been observed in the company of an
adult female up to six months after fledging (Danks et al. 1996). The female bird
builds the nest, incubates the single egg and feeds the nestling with no help from the
male. The slow reproductive rate (one egg per year) and long incubation and fledgling
periods of chicks may be important factors contributing to their decline (Bock and
Clench 1985).
52
4.3.2 Diet
The Noisy Scrub-bird largely forages in leaf litter on the ground, but will also forage
in low shrubs, bases of clumps of rushes and in decayed wood (Smith and Calver
1984). They are predominantly terrestrial insectivores, flushing insects from the litter
and turning over leaves with a flick of the head to expose prey. They have strongly
developed cervical muscles that may be associated with the use of the head to clear
leaf litter when feeding (Bock and Clench 1985). They have also been observed
feeding on dead grasstrees (Xanthorrhoea spp) and fallen logs. Ants, beetles and
spiders comprise 76% of all prey eaten (Danks and Calver 1993). The diet of the
adult and nestling Noisy Scrub-birds differ (Danks and Calver 1993), with the female
feeding the nestling a wide variety of invertebrates and the occasional small
vertebrate. A minimum of 19 taxa are potential prey items for nestlings, including
prey from the Araneida, Orthoptera, Blattodea, Chilopoda, Hymenoptera and
Oligochaeta families and larvae (Smith and Calver 1984). Spiders and crickets
comprise 80% of the nestling diet by number but only 16% of the diet of adults
(Danks and Calver 1993). Frogs (Crinea spp.) and small lizards (Phyllodactylus spp.)
have also been observed as prey items fed to nestlings (Smith and Calver 1984). The
availability of specialist foods is not essential to the survival of the Noisy Scrub-bird
given their generalist insectivore foraging habits.
In 1842-1889, the Noisy Scrub-bird was found in several localities around the southwest coast of Western Australia, including Waroona, Augusta, King George Sound,
Torbay, Margaret River, Albany and Mount Barker (Robinson and Smith 1976; Smith
and Robinson 1976; Smith and Forrester 1981). It is hypothesised that these
populations were relics of a more widespread and abundant ancestral meta-population,
probably dating back to the Early Tertiary (Bock and Clench 1985). Dramatic
population declines in the first 60 years after European settlement is thought to be
caused by the increased use of fire and clearing of the forest habitat (Smith and
Forrester 1981). The Noisy Scrub-bird was rediscovered at Two Peoples Bay, 40 km
east of Albany in 1961 after 72 years of presumed extinction (Fig. 13; Webster 1962,
Danks et al. 1996). The rugged terrain and poor soils at Two Peoples Bay made the
area unsuitable for agriculture or pastoral development and allowed the survival of a
small population. The topography of the area also protected the species, with the
passage of fire naturally limited by granite ridges, although all major gullies have been
burnt at some stage. This fortuitous combination of geographic features is not repeated
elsewhere in the bird’s former range (Danks et al. 1996) and searches in the other
former ranges have failed to locate other populations (Smith 1985). The Two Peoples
Bay area was reserved as an ‘A’ Class Nature Reserve for the Conservation of Fauna
in 1967 to protect the Noisy Scrub-bird and its habitat. The reserve is 4745 ha and is
53
recognised as the most important area for ensuring the conservation of the Noisy
Scrub-bird as it contains the largest and most genetically diverse populations (Orr et
al. 1995).
Fig. 13. Former (open boxes) and existing (closed boxes) distribution of the Noisy Scrub-bird
(Danks et al. 1996).
54
The primary habitat of the Noisy Scrub-bird is the wetter areas of the jarrah
(Eucalyptus marginata) forest where there is some break in the canopy, such as along
streams and on the margins of swamps (Robinson and Smith 1976). Common plant
species associated with these vegetation communities include bullich (E. megacarpa),
tea-tree (Leptospermum spp.) and rushes (Lepidosperma spp.) (Smith and Robinson
1976). At Two Peoples Bay, the birds inhabit coastal forest that occurs within steep
heavily vegetated valleys and along damp soakage lines that drain seawards in the area
of Mt Gardner (Smith and Robinson 1976; Smith and Forrester 1981). The birds are
found around springs, the base of rock faces, inter-dune swales and overgrown
swamps. The Noisy Scrub-bird also inhabits gullies in very thick heathland at Two
Peoples Bay, though this was not a common habitat when the bird was more
widespread (Robinson and Smith 1976). The preferred habitat is long unburnt
vegetation with a dense lower stratum that provides protective cover and an ample
invertebrate food supply (Orr 1995). The habitat is also usually wet or a moisturegaining site and the vegetation is characterised as low forest (5-15 m high) (Danks et
al. 1996). More open areas with thick litter accumulation are required for feeding
habitat, making ideal Noisy Scrub-bird habitat areas of very dense cover interspersed
with small open areas (Danks et al. 1996).
The species small size, elusiveness and preference for dense habitat make it difficult
to carry out a visual count of the Noisy Scrub-bird population (Smith and Forrester
1981). Conventional individual marking methods that rely on recapturing or
resighting marked individuals are of limited use (Portelli 2004). Instead, the
distinctive loud and penetrating territorial song of the male, which is heard from 1.5
km on a calm day, is the only practical means of detecting the presence of the species.
The male population at Two Peoples Bay was estimated at 40-50 individuals between
1970 and 1973 (Smith and Robinson 1976). In 1983, the number had increased to 138
males, probably due to the absence of fire from the area since 1970 (Smith 1985).
Since 1975, the population has extended out of the headland to the south-west of Two
Peoples Bay to form a subpopulation around Lake Gardner (Smith 1985). In 1994, the
population along the south coast (the Albany Management Zone), including
translocation sites, numbered 474 males (Danks et al. 1996), which equated to
approximately 1100 Noisy Scrub-birds (Orr et al. 1995). This is based on the
calculation of 2.5 birds for every singing male (Danks et al. 1996). The Albany
Management Zone covers 4330 ha over 50 km of coastal and near coastal country
south and east of Albany (Danks et al. 1996). Populations in this area now occur at Mt
Gardner, Mt Manypeaks, Mermaid, Waychinicup, Angove-Normans, Mt Taylor, Mt
Martin and Bald Island (Fig. 9). In 1999, 586 singing males were recorded in the
Albany Management Zone. In 2002, the total population in south-west Western
Australia was estimated at 1,200 individuals, including several new small populations
translocated to areas within the Darling Range. In the summer of 2004/2005 there
was a wildfire at Mt Manypeaks. However, despite the fire the number of territorial
singing males increased from 32 to 61 between 2005 and 2006, and many of these
55
were unexpectedly recorded in the area that was burnt (Tiller 2007). The wet winter of
2005 immediately after the wildfire promoted rapid regeneration of some of the
affected area, likely making the area suitable for continued habitation.
Noisy Scrub-birds can have long-term territories that are occupied continuously for at
least ten years if they have a good food source and suitable breeding habitat (Smith
and Forrester 1981). Male core territories are 0.75-2.25 ha in size and are separated
from neighbouring male core territories by 200 – 500 m (Smith 1985). The territory
area is best approximated by the length of the territory because most are confined to
gullies or linear patches of eucalypts. On this basis, size varies between 100 and 300
m (Smith and Robinson 1976). While the male spends most of his time in one or two
small core areas, which probably have the best reserves of food, they may have larger
home ranges that vary from 6-9 ha (Smith and Robinson 1976; Smith 1985). Young
males establish ephemeral territories on the outer limits of existing territories, with the
weak being chased off by dominant males. Males will replace and defend a vacant
territorial area, with replacement being within very short time periods (days) (Danks et
al. 1996).
4.5 Key threats
4.5.1 Fire
Fire is potentially the most serious threat to the continued survival of existing
populations of the Noisy Scrub-bird. The disappearance of the Noisy Scrub-bird from
most of its former range is thought to be due to the change in fire regime from that of
Aboriginal practices to Europeans (Danks et al. 1996). It appears that 10-12 years of
vegetation growth is required after fire before the habitat is suitable for the Noisy
Scrub-bird (Orr et al. 1995), although in some cases re-colonisation has been recorded
one to four years post-fire (Smith 1985; Tiller 2007). Recovery of invertebrate food
supply rather than nesting requirements is thought to drive re-colonisation after fire
because nesting areas close to swamps and streams remain relatively intact through
fire. It is unknown how long unburnt forest will remain a suitable habitat, although it
is thought from records of the fire history that at least 40 years is acceptable (Smith
1985). At Two Peoples Bay, males are defending sites with a post-fire vegetation age
of more than 50 years (Orr et al. 1995). The Noisy Scrub-bird population at Two
People’s Bay near Albany has a fire exclusion management regime, with no
prescribed burning planned unless continued research and monitoring indicates the
habitat is becoming unfavourable and prescribed burning is recommended (Orr et al.
1995).
56
4.5.2 Predators
The eggs and chicks of the Noisy Scrub-bird are vulnerable to predation due to the
nest’s placement close to the ground. The Yellow-footed Antechinus (Antechinus
flavipes), the Southern Bush-rat (Rattus fuscipes), the introduced black rat (Rattus
rattus) and the chuditch (Dasyurus geoffroii) are possible predators (Smith and
Robinson 1976; S. Comer pers. comm.). Predation from reptiles is largely avoided due
to inactivity of reptiles during the timing of the breeding season of the birds (Orr et al.
1995). The introduced fox (Vulpes vulpes) and cat (Felis catus) appear to be less of a
threat due to the dense habitat birds occupy along the south coast. Additionally,
population increases at Two People’s Bay were recorded prior to the implementation
of the fox control program in 1988 (Orr et al. 1995). It is likely that populations
translocated to the more open jarrah-marri forest will be more at risk from predators
such as foxes and cats. Feral pigs, while not a predator of the birds, also impact on
Noisy Scrub-birds through habitat disturbance. They dig extensively in swamps and
dramatically reduce available leaf litter and likely food sources associated with the
litter layer.
4.5.3. Habitat loss
Loss of habitat due to land clearing for agriculture and urban development have also
likely contributed to the declines and range contractions of the Noisy Scrub-bird. They
are highly dependent on habitat for food resources and nest locations, and their
dependence on ground leaf litter and associated invertebrate prey means that loss of
habitat leads to rapid and long-term loss of populations from areas they previously
occupied. Also, due to the patchy distribution of populations over past decades,
populations have probably become increasingly isolated limiting the potential for recolonization of habitats that have been suitably restored.
4.5.4 Disease
The soil-borne pathogen, Phytophthora cinnamomi (cause of Phytophthora dieback)
may pose an indirect threat to the Noisy Scrub-bird as dieback affected areas may
have reduced habitat quality and plant availability. However, it has been hypothesised
that the colonisation of dieback resistant rush and sedge species in affected forest may
favour the Noisy Scrub-bird due to their nesting requirements. Most of the reserve at
Two People’s Bay near Albany is affected by dieback, yet the population of the Noisy
Scrub-bird has continued to increase (Orr et al. 1995).
57
A Noisy Scrub-bird Recovery Team was established in 1992 to prepare and oversee
the implementation of a recovery plan for the Noisy Scrub-bird. The team comprises
officers from the Department of Environment and Conservation (DEC), the Shire of
Albany, Commonwealth Scientific and Industrial Research Organisation (CSIRO),
Australian Nature Conservation Agency (ANCA) and volunteer representatives (Orr et
al. 1995). Management of the Noisy Scrub-bird has occurred since 1986 under the
formal management plan ‘CALM’s Wildlife Management Program No. 2: the Noisy
Scrub-bird’ (Burbidge et al. 1986). An updated plan ‘CALM’s Wildlife Management
Program No. 12: Noisy Scrub-bird Recovery Plan’ (Danks et al. 1996) ran from 1993
– 2002 and aimed to increase the number of subpopulations and individuals until
intensive management is no longer necessary for its survival. DEC began drafting the
‘South Coast Threatened Birds Recovery Plan’ in 2004, which will cover four
threatened taxa, one of which will be the Noisy Scrub-bird. Once finalised and
approved by DEC, the recovery plan will then be submitted to the Commonwealth for
adoption under the Environmental Protection and Biodiversity Conservation Act
1999. The South Coast Threatened Birds Recovery Team presently meets
approximately twice a year and an Alcoa representative from the Research
Department is invited.
Fire exclusion is presently the major habitat management strategy for conserving the
dense habitats and associated invertebrate food supply required by the Noisy Scrubbird (Orr et al. 1995). Complete fire exclusion is in contrast to the jarrah forest fire
management regime, where prescribed burns are undertaken on an 8-15 year rotation
to reduce fuel loads and the likelihood of wildfire. Alcoa provides funding as part of
the Alcoa/DEC Associated Works program to undertake mine protection control burns
within its mining lease. The burns are undertaken by DEC and the fire management of
swamps with Noisy Scrub-birds is managed separately. These swamps are excluded
from control burns as a precautionary management action to minimise impact on their
habitat. However, tailoring a fire regime to suit the habitat requirements of the NoisyScrub bird is recommended. This is currently being investigated for another threatened
species with specific fire seral stage requirements, the quokka (Setonix brachyurus)
(see page 26). A disadvantage of fire exclusion is the resultant build-up of fuels that
may lead to more extensive and damaging wildfires. However the Noisy Scrub-bird
area of occupancy is small (~2 ha core territory size) and generally limited to narrow
strips of swamp vegetation. Risks of wildfire can be minimised by creating fire-breaks
and appropriate buffers through adjacent forest fuel reduction burning (Harris 2007).
58
There have been no Noisy Scrub-birds recorded in the history of Alcoa’s long-term
fauna monitoring program (LTFMP). DEC has however reintroduced Noisy Scrubbirds to the northern jarrah forest into swamp and stream zone areas, some of which
occur within Alcoa’s mine lease. During a pre-mining survey of Larego (a planned
mine region to the south of Willowdale) in 2006, it was discovered that a conveyor is
planned to pass a translocation site with Noisy Scrub-birds near Samson Brook
(EMRC 2006). These birds were translocated between 1997 and 2001. The proposed
conveyor alignment is also close to suitable colonisation areas to the north, south and
west that may enable population expansion (EMRC 2006). While the conveyor is
planned to only cross a narrow section of the wetland and may not form a physical
barrier to movement, the noise and general disturbance of the region may have an
impact on birds by affecting mating and breeding success and ultimately continued
establishment of a viable population. Special consideration should be given to the
management of this population.
Noisy Scrub-birds translocated to the northern jarrah forest require intact riparian
vegetation as habitat and to disperse. Corridors of vegetation connecting existing
populations to suitable habitat nearby will facilitate dispersal (Orr et al. 1995). In
Alcoa’s bauxite mining areas there are occasions where there is direct disturbance of
stream zone vegetation due to the requirement of haul roads and conveyors (such as
that at Larego) to cross stream zones to gain access to areas of ore. Stream zone
vegetation is classified as informal Comprehensive, Adequate and Representative
(CAR) reserves of high conservation value by the Commonwealth of Australia and the
State of Western Australia’s Regional Forest Agreement 1999, and disturbance
requires special approval. Where disturbance is unavoidable, Alcoa is investigating
installing fauna underpasses that will link the vegetation on either side of the road and
provide potential Noisy Scrub-bird populations and other fauna with a safe means of
traversing the road. In 2007 Alcoa approached Aprasia Wildlife Services to conduct a
desktop review of fauna friendly underpasses and to recommend types of underpass
structures that would facilitate the movement of native fauna, specifically the Noisy
Scrub-bird, within its operation areas at Larego. Internal structures, such as a brushed
fenced area, timber runs and branches were suggested for placement within the
underpass to provide protection and encourage fauna movement (Harris 2007).
It has been reported that young post-mining rehabilitated sites support a bird
community more similar to that of stream zones than upland jarrah forest (Christensen
1997; Craig unpublished). There may be potential for use of young rehabilitated sites
by the Noisy Scrub-bird adjacent to stream zone areas where birds are known to occur.
59
Animal translocation can be an important management practice that secures species
against further loss due to threats such as wildfire. The Noisy Scrub-bird population at
Two People’s Bay provides a source of birds for translocation to other areas, with 125
birds translocated as of 1994 to seven areas over an 11 year period (Orr et al. 1995;
Danks et al. 1996). A captive breeding program was established in 1975 at the
CSIRO’s Helena Valley Research Station, however it proved difficult and expensive,
and was short-lived (Danks et al. 1996). The first translocations occurred in 1983 and
1985 to Mt Manypeaks east of Two People’s Bay. From 1990 to 1996, translocations
to Gull Rock National Park, Waychinicup National Park, Bald Island and Torndirrup
National Park were implemented, resulting in a scattering of small populations in the
area between Albany and Cheyne Beach on the south coast of Western Australia
(Danks et al. 1996). More distant translocations to Walpole-Nornalup National Park
150 km west of Two Peoples Bay failed within a couple of years, possibly due to siterelated factors (Danks et al. 1996). In 2006, eight male Noisy Scrub-birds were
translocated from the Mermaid-Waychinicup area near Cheynes Beach to karri forest
in Porongurup National Park (Comer 2007). Prior to release, vegetation suitability
and leaf litter invertebrate food supplies were sampled. Birds were fitted with radio
transmitters to assist with population monitoring.
From 1997 to 2003, DEC reintroduced the Noisy Scrub-bird to eight areas within the
northern Darling Range, some of which occur within Alcoa’s mine lease. A total of 60
males and 20 females were released into habitat assessed as suitable for Noisy Scrubbirds (Table 1). Males were introduced to a new area and if successful, females were
introduced the following season (Harris 2007). In 1998, Alcoa contributed $20,000
towards the monitoring of the Darling Range translocation program, specifically to fit
released birds with radio transmitters. Until recently, DEC undertook annual
monitoring of survival and breeding. Only a small number of the birds released in the
Darling Range have persisted. In 2000, approximately five of the 23 males released at
Upper Harvey were recorded singing. In 2006, only one of the six males released at
Sixty-One Form and only one of the four released at Samson West were surviving. It
is thought the male at Sixty-One Form is a new individual, indicating that breeding
may have occurred in the Darling Range (Comer and Rule 2007). DEC researchers are
currently compiling a review of the Noisy Scrub-bird translocation program in the
Darling Range and investigating possible causes for the lack of successful bird
establishment.
Habitat quality seems to be a vital determinant of successful translocation as birds
tend to stay close (200 – 800 m) to their release site (Danks et al. 1996; Comer 2007).
Extensive research and site surveys are conducted prior to release to determine the
best location for reintroduction. Experience has shown that the creation of a thriving
60
population by translocation may take ten years after the initial release (Danks et al.
1996).
Table 1. Releases of male (M) and female (F) Noisy Scrub-birds from 1997-2003 in the
Darling Range (DEC, unpublished data 2007).
Release area
Samson Brook
Upper Havey
Falls Brook
Sixty-One Form
King Jarrah West
Chasede Road
Samson West
Tiger Road
Total
1997
M
F
6
7
1998
M
F
4
8
1
5
1999
M
F
8
2000
M
F
3
2001
M
F
2002
M
F
1
5
5
2
1
1
1
5
4
5
13
0
13
5
8
3
10
1
14
1
1
1
1
3
2
4
2003 Total
M
F
10
28
5
11
2
1
9
5
1
6
6
0
0
4
80
While feral predators, the fox and cat, are not considered a major threat to existing
populations in the south-coast around Two Peoples Bay, individuals translocated into
the more open habitats of the northern jarrah forest of the Darling Range may be at
risk. DEC manages habitat around all Noisy Scrub-bird release sites in the Darling
Range with fox baiting and feral pig control (Comer and Rule 2007). A primary goal
of the “Western Shield” predator control program (formerly Operation Foxglove) is to
provide large areas of fox controlled forest habitat suitable for translocation of
threatened species considered locally extinct within the northern jarrah forest, such as
the Noisy Scrub-bird (de Tores 1999). One of these was the secure conservation area
of Lane Poole Reserve, where Noisy Scrub-bird translocations have been carried out.
Alcoa’s continued financial contribution to the “Western Shield” program is important
for management of the Noisy Scrub-bird in mining leased forest (see page 10 for more
detail).
Rodents such as the native bush rat (Rattus fuscipes) and feral black rat (R. rattus)
may be more important predators of eggs and chicks of the Noisy Scrub-bird. While
this has not been substantiated, studies reveal rodents to predate on eggs and chicks of
ground nesting birds (Atkinson 1985; Garnett and Crowley 2000). In the Albany
Management Zone, predators such as the southern bush rat are considered a threat to
the persistence of local Noisy Scrub-bird populations and so are targeted for control
using chicken egg baits injected with 1080 poison. In the northern jarrah forest within
Alcoa’s mining lease, mammals have been monitored at stream zones as part of
Alcoa’s long-term fauna monitoring program (LTFMP). Bush rats have never been
61
recorded over the past 16 years of monitoring, but feral black rats have been
consistently recorded, particularly around stream zones since 1992 (EMRC, 2006).
Predation by black rats may be one of many factors contributing to the poor
translocation success of Noisy Scrub-birds in the northern jarrah forest. Subsequently,
control programs of introduced rodents should be considered at translocation sites.
The long-unburnt vegetation requirements of the Noisy Scrub-bird in the jarrah forest
is seemingly related to the provision of an ample invertebrate supply in the
undisturbed litter layers, while the dense rush riparian vegetation of streams provide
cover for nesting. Alcoa has research projects investigating the presence of
invertebrate species in rehabilitated sites in comparison with unmined forest sites and
the effect of fire on invertebrate populations.
4.7 Recommendations
The following actions are recommended for management of the Noisy Scrub-bird in
Alcoa’s mining lease:
 Liaise with DEC about the outcome of the Darling Range noisy scrub-bird
translocation program and future translocation options following review of the
program.
 Contribute funding toward control of likely Noisy Scrub-bird
predators/disturbers such as rats, foxes and pigs through the Alcoa/DEC
Associated Works or DECAFE programs if further translocations are
implemented.
 Investigate management options (including a fauna underpass) for the Noisy
Scrub-bird population at Samson Brook in response to the conveyor alignment
for the new Larego mining region if DEC and/or Alcoa monitoring reveals
birds are persisting in the area.
62
5. PEREGRINE FALCON (Falco peregrinus)
The Peregrine Falcon, Falco peregrinus, is given special protection under Western
Australia's Wildlife Conservation Act 1950. It is listed as "Specially Protected Fauna:
Schedule 4 - Fauna that is in need of special protection despite not being declared as
rare or likely to become extinct". It is not listed under the federal Environment
Protection and Biodiversity Conservation Act 1999 (EPBC Act). It is listed as “Least
Concern” on the World Conservation Union (IUCN) 2007 Red List of Threatened
Species (last assessed 2004; IUCN 2007) because “world populations appear to be
stable and the species is not believed to approach the thresholds for the population
decline criterion (declining more than 30% in ten years or three generations)”.
The Peregrine Falcon is a large, powerful bird of prey that has a near global
distribution, breeding on all continents except Antarctica (Ratcliffe 1993). It shows
morphological variation across its range, with 20 recognised sub-species based on
distinct colouration and size (Brown and Amadon 1989; White 1987). In Australia,
non-migratory populations of Falco peregrinus macropus occur along the eastern twothirds of the continent. This sub-species is replaced by Falco peregrinus
submelanogenys along the coast of Western Australia (Pruett-Jones et al. 1981a).
In Australia, adult peregrine falcons (Falco peregrinus macropus) are monotypic in
plumage (Marchant and Higgins, 1993; Olsen, 1995) and their colouring camouflages
them against being seen by potential prey. In both sexes, the head and cheeks are
covered in a black hood with yellow skin around the eye and on the cere (the skin at
the base of the beak covering the nostrils). The chin, throat, chest and underparts are
creamy white or yellow-cream with fine black barring from the breast to the tail (Fig.
14). The chest is heavyset due to well-developed pectoral muscles for flight. The back
and wings are slate-blue with darker barring. The wings taper to a pointed tip and have
a straight trailing edge in flight. The tail is relatively short. The upper legs are covered
in barred feathers while the lower legs and feet are yellow. While the sexes are similar
in colouration, they differ markedly in size, with females significantly larger than
males (Baker-Gabb, 1984). Indeed, male and female adults do not overlap in any of
the common morphometric characteristics including weight, wing length and culmen
length. Sexual dimorphism is evident as early as the latter stages of the nestling period
(35-40 days) (Olsen 1995; Boulet et al. 2001). Peregrines have a body length within
the range 35–50cm and a broad based wingspan of 80–105cm. Female adults weigh
about 900g and males 600g (Marchant and Higgins 1993).
63
The Peregrine Falcon is the fastest bird in the world, reaching speeds of up to 300 km
per hour when swooping on prey. It has been a symbol of speed and power for
centuries, particularly among the ancient Egyptians and Chinese who practiced
falconry as long ago as 2000 BC.
Peregrines give a loud scream or “kee-kee-kee-kee” when communicating with their
mate. They switch between short and long duration calls when alarmed, in defence of
the nest, when returning to the nest with prey, when displaying over food and when in
flight stooping on an intruder (Marchant and Higgins 1993; Jurisevic 1998).
Fig. 14. Adult Peregrine Falcon, Falco peregrinus (www.nationalgeographic.com.au)
64
Peregrine Falcons, like other birds of prey, are relatively long lived (15-20 years in the
wild), with low reproductive rates and low population density. These factors
combined with being at the top of the food chain and limited by prey makes them
particularly vulnerable to human impact.
Peregrine Falcons usually occur in pairs or singly. Pairs generally mate for life and
maintain a home range of about 20 to 30 km2 throughout the year (Olsen 1995). They
do not build nests; rather eggs are laid in recesses of cliff faces, tree hollows or in the
large abandoned stick nests of other birds. Peregrines nest between August and
November with females usually laying one to five eggs (mean clutch size of 2.9)
(Olsen 1982). The female incubates the eggs and is fed by the male on the nest. After
an incubation period of 33 days, the young emerge over two to three days. The young
then spend another 39 days in the nest before they are fully fledged but still remain
dependent on parents until they learn hunting skills. Prey is brought back to the nest
by predominately the male (85% of prey items) and is fed to the nestlings by the
female (Olsen et al. 1998). Young Peregrine Falcons disperse widely, but often return
to their original home area to breed when mature.
As for many bird species, latitude and consequently photoperiod are involved in the
timing of the egg-laying season for Peregrine Falcons (Olsen 1982). Timing of the
egg-laying period is also correlated with temperature, corresponding to the seasonal
influx of migrant prey species and the breeding season of major prey species (Nix
1976; Olsen 1982). For example, peregrines breeding near Canberra usually lay eggs
in the first week of September and fledge young about mid-November (Olsen and
Olsen 1988). The influx of migrant prey species into the area, which starts in August,
peaks dramatically in November and December, coinciding with the fledging of
peregrine young (Nix, 1976).
5.3.2 Diet
There are no diet studies of Peregrine Falcons in Western Australia. All known
information comes from studies in Victoria and the Australian Capital Territory
(ACT) where peregrines prey almost exclusively on birds (94-99% of diet) and rarely
on mammals and insects (Pruett-Jones et al. 1981a; Olsen and Tucker 2003). Eightynine species of birds were identified from remains of prey collected at nest sites. The
importance of each species to the total diet varied considerably. Three species (feral
pigeon, Galah and common starling) composed 52% of the diet of Victorian
populations (Pruett-Jones et al. 1981a). Parrots in general were a common prey item,
making up 36% of the diet and found at over 90% of eyries. Common starlings and
parrots (Galahs, Crimson Rosellas, Eastern Rosella) were also common in the diets of
65
peregrines in the ACT (70% of the diet) (Olsen and Tucker 2003). Differences in diet
across regions generally reflect the distribution of prey (Pruett-Jones et al. 1981a;
Olsen and Tucker 2003).
In Western Australia, the common starling is a recent arrival (first recorded in the
1970’s) and control measures are being implemented by the Department of
Agriculture and Food to eradicate this pest or at the least keep them at low densities
(M. Massam, pers. comm.). Hence they are not likely to serve as an important food
item for peregrines as they do in eastern Australia. However, several bird species
including the Galah, Corella and Rainbow Lorikeet that are not native to Western
Australia but have successfully established because of their ability to use disturbed
and cleared habitats, are likely to be important food items where native prey has
declined due to loss of habitat.
The hunting behaviour of Peregrine Falcons varies according to the hunting conditions
(Pruett-Jones et al. 1981a). In open habitats, peregrines often catch their prey on the
wing. They have excellent vision and the ability to focus on moving objects and so
can sight prey up to several kilometres. On sighting prey, peregrines follow a curved
path towards it (reducing the need to turn their head and cause drag) and as they close
in on the prey, they fold their wings and dive. Pulling out of the dive before impact,
they contact the prey with open claws, often killing it on impact. The prey is then
carried off to a perch or nest, where it is plucked and eaten. In forested and woodland
areas, where visibility is impaired, Peregrine Falcons fly low in attempts to force
potential bird prey upwards (Pruett-Jones et al. 1981a). In hunting flocks of Galahs
using this method, the falcon would typically take prey that attempted to drop and
make cover. Co-operative hunting by mated adults has been commonly recorded
(Pruett-Jones et al. 1981a). One peregrine would fly close to the prey, forcing it to
take flight, while the second peregrine would come in close behind and take the prey.
The Peregrine Falcon is found across Australia, but is not common anywhere. It is
widespread in Western Australia, preferring rocky ledges, cliffs and watercourses for
breeding (Olsen 1982), though population densities and distribution and how these
have changed in response to human induced changes to the landscape are unknown.
Peregrine Falcons occupy a wide variety of habitats including coastal cliff-lines, open
woodland, lowland and upland forests, swamps, rivers, inland lakes, mallee, plains,
farmlands and urban areas (White et al. 1981; Emison et al. 1997). It has been the
adaptability of Peregrine Falcons in their use of nest sites that has largely resulted in
such broad use of the Australian landscape. Peregrines worldwide are typically
solitary cliff nesters, and the use of other sites is a regional occurrence, representing
local traditions (Newton 1979), which are established through imprinting of nest
66
selection from adults onto their young (White et al. 1981; Olsen and Olsen 1988). In
Australia, peregrines use a variety of nest types. Cliff sites, commonly ledges, are
widely and predominately used (Olsen 1982; Emison et al. 1997). Large or mediumsized stick nests, made in trees by other birds, and hollows in trees are also important
nest sites, particularly in areas where there are few cliffs (White et al. 1981; PruettJones et al. 1981a; Olsen 1982). The relative use and distribution of these different
nest types is shown in Figure 15. Unlike elsewhere in the world, tree nesting
(particularly stick nests) is widespread among Peregrine Falcons in Australia, having
been recorded in Western Australia (Serventy and Whittell, 1951), South Australia
(McGilp 1934), New South Wales, the Northern Territory (Olsen 1982) and Victoria
(Pruett-Jones et al. 1981a; White et al. 1981). In fact, Australia presently has the
largest known population of tree nesters. The use of tree sites has allowed peregrines
to colonise large inland areas lacking cliffs but otherwise suitable in abundance of
prey. Tree hollow sites are generally concentrated along river courses in river red
gums (Eucalyptus camaldulensis), while stick nest sites are more commonly found in
open plains, mallee, swamps and steep wooded slopes where they are usually in the
abandoned nests of wedge tailed eagles (Pruett-Jones et al. 1981a; White et al. 1981;
Olsen, 1982; Emison et al. 1997). While cliff sites are often repeatedly used from year
to year, tree site use can be variable, presumably in response to local climate
conditions and its influence on the availability of prey. For example, stick nests in the
Victorian mallee are only used in years of high rainfall when ducks and waterfowl are
abundant (N. Favaloro, pers. comm.). Competition for use of tree sites may also
influence their repeated use. In arid Australia, competition for use of stick nests
between peregrines and the black (F. subniger) and grey falcons (F. hypoleucos) may
affect selection of nest sites by peregrines and explain their relative absence from arid
areas (Olsen 1982). Alternatively, peregrine distribution in arid areas may be limited
by intolerance of heat and reliance on water. Indeed, nest sites of peregrines are
generally near streams or large bodies of water (Olson 1982; Emison et al. 1997).
Peregrines appear tolerant of human induced disturbance, using man-made rock faces
for nest sites and taking advantage of introduced prey (pigeons and starlings). In
Australia, they have been recorded using active and abandoned open cut quarries as
nest sites, as well as railway cuttings, dams, buildings and mine shafts below ground
level (Olsen, 1982; Emison et al. 1997). Their use of these areas suggests that
peregrines are not limited by availability of natural nest sites.
67
Fig. 15. Distribution of the major types of nest site used by peregrine falcons prior to 1982:
a) Stick nests (n=55); b) Tree hollows (n=43); c) Cliff sites (n=234) (Olsen 1982).
68
5.5 Key threats
Global declines in Peregrine Falcons occurred during the 1960’s and 1970’s due to the
widespread use of the agricultural pesticide DDT, which causes reproductive failure in
birds of prey via residues accumulating through the food chain (Hickey and Anderson
1968; Ratcliffe 1973). It is unknown how pesticide poisoning affected or continues to
affect peregrine populations in Western Australia, though use of DDT has been
banned in Australia since 1987. The typically low population sizes, low reproductive
rates and reliance on tree nest sites, make peregrine falcons in Western Australia
vulnerable to changes in habitat and prey availability.
5.5.1 Habitat loss
Loss of habitat is a major threat to Peregrine Falcons in Western Australia. While the
eastern sub-species shows adaptation to human induced disturbance in use of nest
sites and exploitation of prey (Pruett-Jones et al. 1981a; Emison et al. 1997), it is
unknown if the western sub-species is similarly adaptable. Additionally, the majority
of individuals in eastern populations select undisturbed nest sites (in coastal cliffs and
old river-side gums) and reproductive success in disturbed relative to undisturbed sites
has not been quantified.
Peregrine Falcons rely on habitat for food and nest sites. In the jarrah forests of the
Darling Plateau where there are no cliffs, it appears that Peregrine Falcons rely most
on tree nest sites, particularly stick nests made by other birds such as wedge-tailed
eagles and whistling kites (see Fig. 15). Loss of large trees through timber harvesting
and clearing will lead to a reduction in available trees that are able to support the
medium to large-sized stick nests preferred by peregrines. Low availability of nest
sites will limit breeding and lead to low numbers of falcons. Disturbance and loss of
habitat also potentially negatively affects the availability of prey for Peregrine
Falcons.
In the wheatbelt and farmland areas of Western Australia, Peregrine Falcons are
particularly vulnerable to the loss of any existing large nesting trees, which are few in
number. No nests have been recorded in the wheatbelt (see Fig. 15), suggesting the
Peregrine Falcon is absent or in very low numbers in the area. Likewise, any loss of
old large trees associated with waterways, lakes and swamps before recruits become
large enough for nesting sites may result in the decline of breeding peregrine falcons
in these areas.
5.5.2 Pesticide poisoning
Following
World
War
II
a
new
and
persistent
pesticide,
Dichlorodiphenyltrichloroethane or DDT, came into widespread use in the control of
agricultural and domestic insect pests. Significant residues of DDT and its derivative
69
DDE have been found in raptors, including the Peregrine Falcon, world-wide (Hickey
1969; Anderson and Hickey 1974; Fox and Lock 1978; Pruett-Jones et al. 1981b). The
impact of DDT on peregrines went unnoticed for a long time. This was due to the long
lived adults continuing to inhabit nesting sites for many years thus masking the low
numbers of young birds and corresponding reduction in the breeding population.
Raptors are particularly sensitive to pesticides because residue accumulates through
the food chain (Hickey and Anderson 1968; Newton 1979). At higher concentrations
it was found to affect avian reproduction by causing the thinning of eggshells (through
inhibition of calcium deposition), increased breakage of eggs, and increased death of
embryos (Reichel et al. 1969). Massive declines in peregrine populations occurred
across the world and many local populations became extinct. Australian populations
were affected, though losses were not as severe as those in the Northern Hemisphere
(Hickey 1969; Ratcliffe 1973, Pruett-Jones et al. 1981b). DDT has now been banned
or its use restricted in most parts of the world. Even so, virtually every animal in the
world now has some traces of DDT in its tissues.
5.5.3 Climate change
Increases in temperature and reductions in rainfall predicted as impacts of global
increases in greenhouse gases, will likely threaten Peregrine Falcon populations in
Australia. Nest sites near water are selected (Emison et al. 1997) and this probably
relates to stable availability of prey. If watercourses and swamps dry with global
warming, as predicted, then prey availability will likely decline, particularly in
migratory bird numbers. Furthermore, studies have shown that the egg-laying season
of peregrines is influenced by temperature, being earlier and shorter in hotter, drier
areas than in more temperate areas (Olson 1982). Declines in the available season for
egg-laying with increases in temperature may result in lower rates of recruitment if the
number of females successfully laying eggs each year declines.
There is currently no Recovery Plan in Western Australia for the Peregrine Falcon.
Alcoa does not mine old growth forest within its lease, therefore preserving virgin
jarrah and marri trees with good potential for nest sites (both stick nests and hollows)
for breeding peregrines. The number of hollows in jarrah and marri trees increases as
the size and age of the tree increases, and trees with large crowns bear more hollows
than trees with small crowns (Whitford and Stoneman 2004). Only three hectares of
old growth forest has been identified within Alcoa’s current mining regions and were
70
protected from adjacent clearing with a 100 m buffer zone of vegetation. Trees were
injected with phosphite in August 2007 to improve protection against dieback.
Artificial nest sites can also be of benefit to nesting pairs of peregrine falcon as
demonstrated by the success of a man-made nest box that environmental staff at Alcoa
Anglesea in Victoria installed in 2004 on the site’s water tower (Fig. 16). A webcam
is used to monitor the nest box which has been consistently used by a breeding pair of
peregrine that have been recorded in the area since 1991. The height and aspect of the
structure is similar to the natural nesting environment of this species.
Alcoa has a ‘Fauna Sighting Record Sheet’ which is distributed across all sites for
employees to record the species and location of fauna in the mining regions. This
information may help identify peregrine nest sites in the northern jarrah forest. It is
important that these nest sites are identified and protected where possible as new
mining regions develop, because nest sites are often used by pairs for life and across
generations (White et al. 1981).
Alcoa has a long-term fauna monitoring program (LTFMP) that was established in
1992. There have been no Peregrine Falcons recorded in the history of Alcoa’s longterm fauna monitoring program (EMRC 2006). Alcoa also undertakes pre-mining
fauna surveys before entering a new mining region to identify any rare or protected
species. To date, peregrine falcons have not been recorded in the mine lease.
5.6.2 Regeneration of native vegetation
Eucalypt regeneration is vital for ensuring suitable nest sites for Peregrine Falcons,
particularly given that veteran and stag trees are in serious decline in many areas,
especially farmlands, with very few seedlings being recruited. Habitat enhancement
through the creation of native corridors and the protection of remnant bushland with
large trees is also important. Alcoa is a major sponsor of the Swan-Alcoa Landcare
Program (SALP), which provides funds for community groups involved in on-ground
revegetation and rehabilitation projects within the Swan and Canning catchments.
Alcoa committed $750,000 over three years to the program between 2007 and 2009,
and has been a sponsor for the past 10 years. Projects involve linking existing native
vegetation corridors, enhancing remnant native vegetation with weed control and infill planting, and planting tree shelter belts on farm properties.
5.6.3 Community awareness and research
The Peregrine Falcon became a worldwide symbol for the environment movement
after the devastating effects of DDT and similar pesticides became known and were
documented in Rachel Carson's landmark book Silent Spring. Alcoa Anglesea
encourages community awareness of the peregrine falcon by posting webcam video
footage of a nesting pair that uses an artificial nest box on site (Fig. 16). Additionally,
71
both the Anglesea and Point Henry sites work with the Victorian Peregrine Project
(VPP) to assist with research and conservation of the species.
Fig. 16. Webcam footage of a breeding pair of peregrine falcon and their chick at a
man-made nest box at Alcoa Anglesea in Victoria.
5.7 Recommendations
The following is recommended for management of the Peregrine Falcon in Alcoa’s
mining lease:
 Opportunistically record nest locations of breeding pairs of peregrine falcon in
current and new mining regions. Train staff and consultants in correct
identification of peregrine falcons to improve the accuracy of sighted
recordings and confirm/disprove that falcons actually use the jarrah forest.
Protect regularly used nest trees during infrastructure planning/construction.
 Develop methods through research to improve the health and survival of
veteran and mature trees in unmined forest to conserve trees with large crowns
that can support suitable stick nests for peregrine falcons.
 Research the impacts of tree thinning in rehabilitation on tree development,
particularly crown development and formation of suitable nest trees for
falcons.
72
6. CARPET PYTHON (Morelia spilota imbricata)
The Western Australian carpet python (Morelia spilota imbricata) is given special
protection under Western Australia's Wildlife Conservation Act 1950. It is listed as
"Specially Protected Fauna: Schedule 4 - Fauna that is in need of special protection
despite not being declared as rare or likely to become extinct". It is not listed under the
federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
It is listed as “Lower risk (near threatened)” on the World Conservation Union
(IUCN) 2007 Red List of Threatened Species (last assessed 1996; IUCN 2007).
Ranked near threatened, M. spilota imbricata presently does not qualify for
Conservation Dependent (i.e. requiring conservation programs to avoid threatened
status), but is close to qualifying for Vulnerable status.
The carpet python, Morelia spilota imbricata, is one of seven subspecies. It is a nonvenomous snake that is distributed across the south-western corner of Western
Australia (Schwaner et al. 1988; Pearson 1993). The other subspecies of carpet python
include M. s. spilota, which occurs along coastal New South Wales; M. s. bredli from
central Australia; M. s cheynei from the Wet Tropics region in northern Queensland;
M. s. mcdowelli from coastal and inland Queensland; M. s. variegata from the
Kimberley and Top End regions; and M. s. metcalfei, which is widely distributed
across the Murray Darling region extending throughout South Australia, inland NSW,
and inland Queensland (Barker and Barker 1994).
The Western carpet python averages 2 m in body length, with reports of up to 4 m.
The sexes are strongly size dimorphic and this is determined primarily by the mating
system (Shine 1994). Adult females can grow to over twice the length and more than
10 times the mass of adult males (Pearson et al. 2002). On Garden Island, males
average 104 cm in body length and 305 g in weight compared with 214 cm and 3.9 kg
for females. This sex difference is due to a reduced rate of feeding in males leading to
an earlier cessation in growth (Pearson et al. 2002). This sex dimorphism is unique
among the other sub-species, which show relatively minor sex differences in adult
body size (Shine and Fitzgerald 1995; Fearn et al. 2001).
Colour patterns vary across their geographical range from pale to dark brown with
black variegations which may form cross bands. The belly is white, cream or yellow,
and can be unmarked or with bold black patterns (Fig. 17). The head is generally pale.
73
Fig. 17. Morelia spilota (Groves 2005).
The lifespan of wild carpet pythons is unknown and little is known of their breeding.
Mating occurs from October to mid-December and is stimulated by a well-developed
sour on both sexes (Pearson et al. 2005). Adult males are thought to be reproductively
active every year, while females only breed every second year or less because of the
time required for emaciated post-reproductive females to rebuild energy stores
(Pearson et al. 2002). Females have a single ovulation in late spring or early summer
and males increase their home range in spring in search for females to mate with.
Males of some sub-species of Morelia have been recorded to engage in physical
battles over mating rights to females (Shine 1994; Shine and Fitzgerald 1995). After
mating, females lay between 14 and 35 eggs, which they deposit in sheltered sites
such as hollow logs (Slip and Shine 1988a). A clutch of eggs can weigh up to 25% of
the female’s body weight. Females will stay with the eggs for up to 60 days
controlling the temperature of the clutch by shivering to generate heat. Eggs hatch
between 63 and 71 days after laying, usually in March, and young are independent
from the day of hatching. Young disperse away from the nest and establish their own
home range.
Western carpet pythons do not appear to inhabit exclusive territories with males,
females and juveniles showing extensive overlap in radio-telemetry studies (Pearson
et al. 2005). In a study of populations on Garden Island and in the Dryandra
Woodland, both males and females moved on average 100 m during the active season.
Mean home ranges were also similar for the two study areas: means of 17.7 and 17.3
ha, and this is consistent with measures for other ambush predators (Pearson et al.
74
2005). Seasonal activity did vary between the locations, likely in response to varying
climatic conditions. In the Dryandra Woodland, where winter day and night time
temperatures were cooler, all python age/sex classes retreated to over-winter shelter
for over 3 months during which time they seemingly ceased feeding (Pearson et al.
2005). Most of the overwinter refuges used by Dryandra pythons were hollows in
trees, with many pythons returning to the same hollow in consecutive years.
Comparatively, on the milder climatic habitat of Garden Island, both males and
juveniles continued to move and feed during winter. In the northern jarrah forest,
individuals have been recorded hibernating for up to 6 months over the cooler months,
overwintering off the ground in tree hollows (G. Bryant, pers. comm.). Like the
Dryandra pythons, they show high site fidelity from year to year for overwinter refuge.
6.3.2 Diet
Carpet pythons are predators and carnivorous feeders. They include a wide taxonomic
diversity of terrestrial prey including mammals ranging in size up to small wallabies,
birds and reptiles (Wilson and Knowles 1988). For some populations, the diet of adult
pythons consists almost entirely of mammals (91% of 44 records) and mainly Rattus
species (52% of mammalian prey) (Slip and Shine 1988b). They are ambush
predators, strangling their prey and swallowing it whole. They generally rely on
structural components of habitat such as logs or dense ground vegetation to hide and
from which to ambush prey (Pearson et al. 2005). In summer, adult pythons can spend
more than 80% of their time coiled in an ambush posture near mammal trails, often
occupying the site for several days (Slip and Shine 1988b).
The Western carpet python is distributed across the south-western corner of Western
Australia from Northampton to Albany and east to Kalgoorlie, and along the southern
coastline of both Western Australia and South Australia (Smith 1981; Schwaner et al.
1988; Pearson 1993). Populations also occur on several offshore islands including St
Francis Island (South Australia) and islands of the Archipelago of the Recherche
(Western Australia). Sizeable populations have been recorded in conservation
reserves, State Forests, the Geraldton area and on Garden, Mondrain and West
Wallabi Islands (Pearson 1993). Populations also occur in the Perth outer metropolitan
region in forested areas and adjacent suburbs of the Darling Range (Pearson 1993).
The western carpet python has disappeared and declined in part of its range in the past
40 years, particularly where large areas of bushland have been cleared such as the
wheatbelt and Esperance district (Bush 1981). In the wheatbelt it has been reported
from a few large conservation reserves such as Dryandra, Tutanning and the Stirling
Ranges (Serventy 1970; Pearson 2005). Sightings have also been recorded in small
bushland remnants (Pearson 1993).
75
Carpet pythons are known to use a variety of habitats including coastal heathland,
open woodland, rock outcrops, tall forests and semi-arid shrublands (Pearson 1993;
Barker and Barker 1994). They are arboreal, terrestrial, and rock-dwelling. They
shelter in hollow tree limbs, hollow logs on the ground, in rock crevices and in
burrows made by other animals. Preferred logs are generally 150 mm in diameter,
with a hollow that extends more than 1 m. They show flexibility in their habitat use,
largely using logs and tree hollows for shelter when available, but also making use of
dense shrubs when preferred shelter is not available (Pearson et al. 2005). For
example, pythons at Dryandra are predominately found in hollows, either in standing
trees or in logs on the ground. On Garden Island they are largely terrestrial, generally
sheltering beneath prickle lily shrubs that cover most of the Island. In the northern
jarrah forest, large hollow logs greater than 50 cm diameter are selected during the
warmer months, and tree hollows off the ground in jarrah trees are selected in winter
(G. Bryant, pers. comm.). The common factor for all populations across these
localities is the need for concealment. Pythons are rarely found in exposed habitats,
but rather shelter in whatever retreat is available.
6.5 Key threats
The Western carpet python has declined across much of south-western Australia
(Smith, 1981). Likely threats contributing to their decline include: loss and
degradation of habitat, competition for food from introduced predators, declines in
prey species due to changes in and loss of habitat, changing fire regimes and humans
removing individuals from native habitat for commercial pet trade. Carpet pythons
occur at low densities and are patchily distributed making them vulnerable to these
threats and stochastic events.
6.5.1 Habitat loss
Habitat loss and fragmentation is a major cause of declines and range contractions of
the western carpet python (Pearson et al. 2005). Being a large ambush predator, carpet
pythons rely on vegetation structure for concealment from potential prey and
predators, and small changes to habitat can affect the viability of populations (Reed
and Shine 2002). Logs are particularly important components of habitat required by
pythons because they provide shelter, brood sites and ambush locations (Barker and
Barker 1994; Pearson et al. 2005). Hollow bearing trees also provide important habitat
for carpet pythons, particularly in the winter months in the jarrah forest (G. Bryant,
pers. comm.). Changes in habitat can also negatively affect prey species and so reduce
the availability of prey.
Habitat loss due to clearing for agriculture and metropolitan development has been a
major contributor to the range contraction of the western carpet python. It is now
rarely recorded in most of the wheatbelt region due to loss of habitat resulting from
76
intensive cereal production, and is rarely recorded on the Swan Coastal Plain (Smith,
1981; Pearson 1993). In the jarrah forest, land is managed for multiple purposes
including timber harvesting, prescribed burning, water catchment management,
bauxite mining and recreation, all of which potentially result in changes to the habitat
required by carpet pythons for persistence.
6.5.2 Feral animals
Feral predators, the European Red Fox (Vulpes vulpes) and the feral cat (Felis catus)
are a probable threat to carpet pythons. The most likely mechanism of impact is
competition for prey resources such as small mammals, reptiles and birds. Impacts are
likely to be greatest where both cats and foxes are present because of the different
hunting strategies of these predators that overlap with those of pythons. Foxes are
ground cursorial predators, cats are efficient arboreal hunters and pythons are both.
The fox and cat may also have a predatory impact, though this has not been
determined. Juvenile pythons would be at greatest risk.
The effect of fire on carpet python populations is complex and depends on the type of
habitat, the seasonal timing of fire and the intensity of the burn. A critical resource
needed for populations to persist is the availability of suitable hiding places in which
individuals can shelter and brood their eggs, and from which they can ambush prey
(Pearson et al. 2005). In forests where logs are the primary habitat providing shelter,
fire irrespective of intensity would reduce the availability of this critical ground cover.
‘Cool burns’ may result in patchy loss of logs, while ‘hot’ fires would result in more
consistent loss of logs. However, hot fires will also likely kill and fell standing trees
generating a new generation of logs, but will also remove hollow tree limbs used by
snakes as over-wintering sites (Pearson et al. 2005). In habitats where ground
vegetation is critical habitat for either pythons or their prey, fire may be an essential
ecological process that is vital for stimulating soil stored seed. For example, at
Dryandra, Gastrolobium thickets are important shelter and foraging sites for Woylies
(Bettongia penicillata) that are an important prey item for female carpet pythons
(Pearson et al. 2005). These thickets senesce and collapse in the absence of fire but
are reinvigorated with fire which stimulates germination of seed in the soil (Friend
1994). Balancing these requirements and having an understanding of local habitat
requirements of populations is needed to best manage the fire ecology of the jarrah
forests for carpet python populations.
6.5.4 Commercial trade
The commercial trade of pythons as pets and for skins has been identified as
contributing to the decline of some boids, particularly those on islands or in areas
77
where they are declining and subsequent demand is high (Honegger 1978). Western
Australia now has legislation against the commercial exploitation and export of
pythons, but this has only been introduced since 2003. Up until this time, removal of
pythons was un-checked, and given the ease of removing such large, non-venomous
reptiles from the forest, this potentially has been a major factor contributing to
localised declines and extinctions. Even with present legislation, illegal trading is still
a potential issue, the extent of which is unknown. Authorities consider there may be a
substantial trade despite only one person in Western Australia being apprehended
trying to illegally export pythons between 1986 and 1993 (Pearson 1993).
6.5.5 Road kill
Carpet pythons are regularly sighted on or near roads during the summer months on
Alcoa’s mine sites according to the fauna sighting records and road deaths have been
recorded. In the warmer months in the jarrah forest, carpet pythons will bask in the
open, including on roads and tracks, placing them at risk of injury or death due to
vehicle collision (G. Bryant, pers. comm.). In winter this threat does not exist because
they are completely sedentary, over-wintering in tree hollows.
There is currently no Recovery Plan for the carpet python, Morelia spilota imbricata
in Western Australia despite its classification as a vulnerable species.
The jarrah forest and remnants of coastal bushland are particularly important for the
persistence of carpet pythons, given their almost complete absence from the wheatbelt
and Swan Coastal Plain. Retaining large hollow logs, large habitat trees with hollows
and areas of mature forest will help preserve habitat for the carpet python. In the
wheatbelt and along the Swan Coastal Plain, habitat enhancement through the creation
of native corridors and the protection of remnant bushland with established trees is
important. Alcoa is a major sponsor of the Swan-Alcoa Landcare Program (SALP),
which provides funds for community groups involved in on-ground revegetation and
rehabilitation projects within the Swan and Canning catchments.
Rehabilitated mined areas in the northern jarrah forest are young developing
ecosystems and lack hollow logs and tree hollows required by carpet pythons as nest
and over-wintering sites. The return of fauna habitats in the form of piles of logs and
rocks (left on the forest edge following clearing operations) is an important
component of Alcoa’s restoration process following mining operations. Presently log
habitats are placed evenly throughout rehabilitated pits at a rate of one constructed
habitat per hectare. This exceeds the requirements of Alcoa’s completion criteria and
78
working arrangements with DEC of one constructed habitat per two hectares. The
habitats vary in size and shape being constructed from large and small diameter logs,
tree stumps, rocks and soil and are constructed to create openings for fauna of many
sizes. These potentially provide habitat for carpet pythons that may utilise gaps
between logs in the pile to ambush prey, to shelter or to incubate young.
Alcoa contributes to fox control in the northern jarrah forest by funding the Western
Shield program through DECAFE (DEC/Alcoa Forest Enhancement) (see page 10).
The program covers Alcoa’s entire mining lease in the northern jarrah forest and
includes an unbaited control section south-east of the Orion crusher region. The
response of the carpet python to long-term feral predator control has been monitored
as part of a PhD project, but due to the difficulty locating individuals and the
seemingly low numbers and patchy distribution, predator impacts have been difficult
to measure (G. Bryant, pers. comm.). Prey responses to fox baiting have also been
monitored and if densities of small mammal and reptile increase where foxes are
baited, this will likely have positive benefits for carpet pythons (deTores, pers.
comm.).
Cooler spring burns, managed to create a mosaic of varying burnt ages interspersed
with patches of unburnt vegetation are probably preferable for the western carpet
python, as cool burns are less likely than wildfires to remove ground logs and will
reduce the risks of wildfires. Alcoa provides funding as part of the Alcoa/DEC
Associated Works program to DEC to undertake mine protection control burns on an
8-15 year rotation. Research on the effect of prescribed burning patterns and wildfires
on habitat components such as logs is needed to confirm the fire requirements of the
carpet python and is presently being undertaken by DEC researchers (K. Whitford,
pers. comm.).
From 2006 to 2008, Alcoa established a long-term trial to identify optimum densities
and forms of coarse woody debris to encourage return of fauna into rehabilitated
forest. Habitat treatments as part of the trial include varying densities of log habitat
piles, snipped woody debris at varying rates and combinations of these. In 2009/2010,
an additional trial has been established to complement this trial, involving treating
rehabilitated pits with logs scattered individually across pits at a rate of 15 logs per ha.
Hollow logs will also be returned at a rate of 1 - 2 per ha. The trials will be monitored
for the next 15 years to determine the optimum density and configuration of log return
for re-colonisation of fauna including rare and threatened species such as the carpet
79
python. The persistence of fauna habitats over time and in response to prescribed fire
will also be measured as resilient habitats are required given it will be decades before
logs are naturally generated within rehabilitated forest.
Recent research on the effect of fire on fauna habitats determined that the fauna
habitats are able to survive a hot summer wildfire, which is the worst case scenario.
Generally, there is an overall reduction in the number of logs but very few are
completely consumed, with stumps and rocks remaining intact. It is predicted that the
cooler prescribed burns which occur in rehabilitated sites should have only a minor
impact on the habitat value of the log piles.
6.7 Recommendations
The following actions are recommended for management of the western carpet python
in Alcoa’s mining lease:
 Audit log return in post-mining rehabilitation to assess the availability of
hollow logs or protected crevices > 150 mm diameter in the fauna habitats.
These habitats provide carpet pythons with shelter and brooding sites.
 Research the log requirements and suitability of fauna habitats in rehabilitation
as habitat for carpet pythons. Collaborate with DEC scientists who are
conducting research on carpet pythons in unmined jarrah forest.
 Investigate and trial feasible options for return of tree hollows or alternatives
as over-wintering sites for carpet pythons.
 Research the effect of prescribed burning on the persistence of fauna habitats
in rehabilitation and hollow logs in unmined forest to determine the impact of
current prescribed burning practices on availability of brood sites/shelter for
carpet pythons.
 Liaise with DEC researchers regarding alternative methods for the census of
carpet pythons other than current ad hoc sightings. A PhD student is currently
testing the role of pheromones in attracting individuals to sand pads.
 Implement a campaign/reporting system encouraging Alcoa staff and
contractors to report sightings of live carpet pythons on haul roads and bush
tracks to environmental staff so they can be safely moved.
80
SUMMARY AND PRIORITY OF RECOMMENDED ACTIONS FOR
MANAGEMENT OF THREATENED FAUNA
To protect threatened fauna, such as the species described above, within Alcoa’s mine
lease, we need to monitor populations prior and during mining operations, we need to
obtain further data from research on the distribution and habitat requirements of
species, we need to act to protect populations and important habitat through informed
planning of mining operations, and we need to restore suitable habitat post-mining
that will encourage recolonisation of rehabilitation by threatened species.
Management options to achieve these desired outcomes have been discussed in the
preceding sections and will be implemented according to priority, availability of
resources/expertise and opportunity for collaboration with external agencies such as
universities and DEC. Priority is primarily based on the urgency of actions for species
based on our knowledge of existing threats. Commencing more targeted monitoring is
a key priority given that we lack information on the occurrence and distribution of
species within the mine lease.
RECOMMENDED ACTIONS
HIGH PRIORITY
Develop and implement a
chuditch monitoring program
and incorporate into the LTFMP.
Investigate rapid and reliable
methods for targeted survey of
quokkas at swamps/streams as
part of pre-mining fauna surveys.
Map locations of new and
known quokka populations on
Alcoa’s GIS for use in planning
haul road construction at stream
crossings.
Continue
annual
financial
support for intensive fox baiting
around
known
quokka
populations.
Install a haul-road fauna
underpass at a stream crossing
and monitor its effectiveness in
facilitating movement of
quokkas and chuditch up and
IMPLEMENTATION AND MANAGEMENT
PROPOSED
COLLABORATORS
IMPLEMENTATION
DATE
Q2 2010
DEC (Dr Al Glen)
Q4 2011
DEC (Paul deTores)
Helix (UWA)
Q4 2011
DEC (Paul deTores)
Murdoch Uni (PhD student)
Annual
DEC
Q4 2010
Nil
81
down the stream. Likewise
investigate use of standard
culverts under haul roads at
streams.
Liaise with DEC about the
outcome of the Darling Range
noisy scrub-bird translocation
program and future translocation
options.
Incorporate expert surveys of
black cockatoo nest and roost
sites into pre-mining fauna
surveys. Map areas of critical
habitat on Alcoa’s GIS.
Research
the
value
of
rehabilitation as feeding habitat
for black cockatoos.
Trial and test the value of
artificial nest boxes as nesting
habitat for black cockatoos.
Train Alcoa staff/consultants in
accurate identification of
threatened fauna to increase
reliability of sighting records.
Implement a campaign/ system
for reporting by Alcoa
staff/contractors of sightings of
live carpet pythons on roads to
environmental staff so they can
be safely moved.
Develop methods to improve the
health and survival of veteran
and mature trees in unmined
forest to conserve tree hollows
and large crowns for black
cockatoos, peregrine falcons and
carpet pythons.
MODERATE PRIORITY
Research chuditch return into
rehabilitation and use of fauna
habitats.
Erect wildlife signage at sites of
repeated chuditch and quokka
road kill.
Collaborate with DEC to manage
known
quokka
populations
Q1 2010
DEC (Sarah Comer)
Q1 2011
Ron Johnstone (WA
museum) and Tony Kirkby
Q4 2010
Murdoch Uni (Mike Calver,
Hugh Finn, Mike Craig)
Q3 2010
Serpentine-Jarrahdale
Landcare
Q4 2010
Nil
Q2 2010
Nil
Q4 2012
Murdoch Uni (Giles Hardy)
DEC (Richard Williams)
Q1 2011
DEC (Al Glen)
Murdoch Uni (Mike Craig)
Q4 2011
Nil
Q4 2013
DEC (Paul deTores)
82
through
prescribed
burn
planning
and
modelling
preferred seral ages since fire.
Use research and monitoring
data to develop predictive
models for identifying high
conservation
value
feeding
habitat for black cockatoos in
Alcoa's mine lease.
Raise awareness of Baudin’s
cockatoo status among
neighbouring orchardists and
promote non-lethal control
methods.
Opportunistically record nest
locations of breeding pairs of
peregrine falcon and protect
regularly used nest trees during
infrastructure
planning/construction.
Research the impacts of thinning
rehab on tree development,
including: crown development
and formation of suitable nest
trees for peregrine falcons; and
fruit/seed yield as food for black
cockatoos.
Audit log return to rehab to
assess availability of hollow
logs/protected crevices > 150
mm diameter as habitat for
carpet pythons.
Research the log requirements
and suitability of fauna habitats
in rehab as habitat for pythons.
LOW PRIORITY
Use LTFMP, research data, and
invertebrate biomass studies to
compare prey availability for
chuditch in rehab and unmined
forest.
Liaise with DEC to organise an
Alcoa representative on the
quokka recovery team.
Contribute to research of pig
impacts on quokkas and their
Q4 2012
Murdoch Uni (Mike Calver,
Hugh Finn, Mike Craig)
Ongoing
DEC
Ongoing
Nil
Q4 2013
Nil
Q4 2011
Nil
Q4 2012
Murdoch Uni
Q2 2013
Curtin Uni (Jonathon Majer)
Q2 2011
DEC and
Quokka recovery team
Murdoch Uni
83
habitat
(where
opportunity
arises).
Contribute funding to Birds
Australia toward research into
feral
bee
management/eradication.
Provide resources/support to the
Black Cockatoo Rescue Centre.
Research the effect of prescribed
burning and wildfire on the
persistence of fauna habitats in
rehabilitation and hollow logs in
unmined forest to determine the
impact of fire on den availability
for
chuditch
and
brood
sites/shelter for carpet pythons.
Liaise with DEC researchers to
find better methods for the
census of carpet pythons.
Q4 2012
Birds Australia
Q2 2012
Q4 2015
Black Cockatoo Rescue
Centre
Murdoch Uni/UWA
Q4 2015
DEC
84
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Independant Study Contract N395

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