1 1 INTRODUCTION This paper has been prepared to support a

Transcription

Berücksichtigung von Fledermäusen bei der Straßenplanung
Fachgespräch am 24. Juni 2010 in Köln
Erfahrungen mit dem Fledermausschutz im Zuge von
Straßenbaumaßnahmen im Vereinigten Königreich
Experiences of Dealing with Lesser Horseshoe Bats (Rhinolophus hipposideros / Kleine Hufeisennase) in Wales, United Kingdom, Len Wyatt, Welsh Assembly Government
1 INTRODUCTION
This paper has been prepared to support a presentation to the Bats and Road Planning
event held on 24 June 2010 in Cologne, about the work of the Welsh Assembly Government
for Lesser Horseshoe Bats (Rhinolophus hipposideros / Kleine hufeisennase).
The Welsh Assembly Government is responsible for the improvement, operation and maintenance of the motorway and trunk road network in Wales.
The information in this paper relates to large scale new road infrastructure, rather than small
scale projects or maintenance operations.
Its purpose is to:
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Explain the context in which the Welsh Assembly Government has been carrying out its work
Provide information on some of the mitigation measures for Lesser Horseshoe
Bats which have been carried out by the Welsh Assembly Government
Provide principles which have informed the way we have considered these
bats in our work
Provide sources of further information from the UK
It should be noted that the information and mitigation measures described in this paper, may
not apply or work in other situations where the context of the landscape, project details; or
behaviour of the same or other species of bats is different.
2 CONTEXT
UK Population
The lesser horseshoe bat population of the UK is estimated to be around 15,000 – 24,000
individuals concentrated in the south and west of the UK. About half of that population is believed to be resident in Wales. Up to 2008 the population in the UK is believed to be increasing overall. Figures for 2008 onwards are currently not available.
Overview of Lesser Horseshoe bat ecology in UK
In the UK the following features can be used by Lesser horseshoe bats.
1. Summer/Maternity Roosts:
Used during late spring, summer and early autumn. Usually found in:
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Buildings dating from before the 20th Century with heated cellars, roofs, attics
Caves
Structures such as bridges with sufficient space and suitable temperatures. Lesser
horseshoe bats cannot easily crawl into small space, so require larger entrances into
roosts and a large space to fly around in before they come out to feed.
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The largest maternity roost in Wales (before the arrival of pups) is currently c800 individuals.
The sizes of maternity roosts close to our projects range from around 10 to 420 individuals.
2. Hibernacula:
To enable hibernation from winter conditions and lack of insect prey. Usually found in:
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Caves
Unheated cellars
Mines
Ice houses (houses built to store ice during the summer)
Tunnels
Lesser horseshoes will forage relatively close to the hibernacula in winter if temperatures are
warm enough and food is available. It is important to realise that hibernacula can be up to
20km away from the summer/maternity roost. Some summer/maternity roosts can be used
during mild winters. There is currently no evidence that the bats migrate within or to/from the
UK to avoid winter weather.
3. Night Roosts
These are locations used by individual or small numbers of bats as an occasional resting
place between feeding:
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Extensions on entrances to buildings (porches).
Cellars
Open buildings, sheds
Exceptionally they can be found in:
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300mm drainage pipe under a single
carriageway! (one record of one male
found by radiotracking). Also used as a
day roost.
Crevices in rocks (one record of adult bat
entering a crevice during a radiotracking
study in Mid Wales).
Photo: checking crevices for bats in rock
face. Jacobs.
4. Habitats/features used to guide movements
The following habitats/features can be used by bats to guide their movements:
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Well connected hedgerows
Well connected woodland edges
Rivers, streams and linear watercourses
Wire fencing/stone walls – occasional records.
Underpasses and tunnels
Photo: automatic detector at culvert used by
bats. Jacobs.
5. Habitats used for feeding
The following habitats can be used as feeding areas:
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Broadleaved
woodland
and
scrub,
occasionally other types of woodland
Vegetated river corridors
Grassland/wet grassland close to flight
routes or vegetation
Photo: Landscape around Porthmadog.
Maternity roost of 420 individuals next to road at
bottom left. Halcrow.
Lesser horseshoe bats prefer to eat:
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Craneflies (Tipulidae)
Moths (Lepidoptera)
Midges/small flies (Diptera – nematoceran)
There is currently insufficient evidence to confirm whether lesser horseshoe bats use specific
areas in the autumn (known as swarming areas) to socialise like some other bat species.
Legislative requirements
The UK legislation, based on European Community Directives, requires the following to be
undertaken:
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Creation, management and protection of internationally important (Natura 2000) sites.
Environmental Impact Assessment of relevant projects
“Appropriate Assessment”/Assessment of the Implications on European Sites (AIES)
of relevant projects on Natura 2000 sites.
Strict system of protection of individuals and resting/roosting places against killing
and disturbance.
In addition, national legislation allows for the creation, management and protection of nationally important sites; and requires the conservation and enhancement of species within the
legal powers available to carry out the work.
This means that there could be a large number of legislative requirements to be met before a
project can go ahead where lesser horseshoe bats are involved.
Welsh landscape and lesser horseshoe bat distribution
Wales covers 20,779 square kilometres. In comparison England covers 130,422 square
kilometres. The central and northern western areas of Wales are generally dominated by
mountains and hills, with river valleys cutting through them. (see map on Page 5).
Broadleaved woodland and hedgerows can be prominent features of the non-urban lowland
landscape. The main urban areas are concentrated in the coastal areas in the south east and
north of the country. Built up areas in the other parts tend to be much smaller.
Lesser horseshoe bat distribution in Wales is concentrated around North West Wales and
the border areas with England in the South East. There are also smaller populations in South
West Wales, Mid Wales and North East Wales. (See map on Page 6.)
Welsh Assembly Government trunk road and motorway network
The majority of our 1,700km network is located within rural areas. There are two Motorways
(of four to six lanes of traffic) through south Wales (Annual Average Daily Traffic (AADT) in
2008 13,000 to 105,000). The majority of dual carriageways (of four lanes of traffic) are located in south and north Wales. (AADT 2008 10,000 to 75,000). The network is predominately of “single carriageway” standard (with two lanes of traffic – eg: width of the carriageway without verges and hard strips is c7.3m (AADT 2008 1,600 to 17,000).
In many areas the geology and landscape means that the network follows the river valleys,
which also provide the best areas for lesser horseshoe bats. The map below shows the spatial overlap between the road network and lesser horseshoe bat areas.
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Potential impacts of major road infrastructure
In a recent strategic assessment of all of the Welsh Assembly Government’s proposed
transport activities across Wales (including roads) the following potential impacts on three
species of bats (including Lesser Horseshoe Bats) were identified:
POTENTIAL IMPACT (project stage in which the impact may occur)
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Habitat Loss/fragmentation including effects on foraging areas (construction)
Loss of breeding areas, hibernacula etc (construction)
Damage to flight lines between roosting/feeding areas (construction)
Changes to habitats used by species – changes to air quality, water quality and water
flows (construction and operation)
Disturbance to species (eg: direct effects on roosts etc). (Construction)
Noise and vibration disturbance – changes in behaviour (construction and operation)
Visual and lighting disturbance – changes in behaviour (construction and operation)
Wildlife Vehicle Collisions (operation)
Climate change effects – changes in distribution (operation)*
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*Climate change may increase the area of the UK suitable for the bats. MONARCH III
computer based modelling completed in 2007 suggests that the climate space available
may increase to the north and east.
ŚƚƚƉ͗ͬͬǁǁǁ͘ƵŬĐŝƉ͘ŽƌŐ͘ƵŬͬŝŶĚĞǆ͘ƉŚƉ͍ŽƉƚŝŽŶсĐŽŵͺĐŽŶƚĞŶƚΘƚĂƐŬсǀŝĞǁΘŝĚсϯϯϭ
It should be noted that not all impacts are likely to occur in all situations, and for many projects the results of the Environmental Impact Assessment and “Appropriate Assessment”
processes may conclude that certain impacts are not significant.
One of the areas where our knowledge is not so good relates to the way Lesser Horseshoe
bats fly over and around roads, especially as the bats have a number of flight characteristics
which increase the likelihood of impacts on flight lines and potentially mortality caused by
wildlife vehicle collisions.
The following generalised flight characteristics can be identified from published texts and
field surveys:
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A reluctance to fly across open areas. However, the width of open area which the
bats will refuse to cross, or cross less frequently, is currently unknown.
Avoidance of street lights and lit areas, although there is some evidence that the bats
may tolerate some lighting in underpasses. The exact amount is currently unknown.
Flying high over traffic height using tree canopies/crowns; or if tree canopies are not available between 0.5 and 1.5m above the road surface. Surveys have shown that removal of
tree crowns or gaps in
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canopies may force the bats down to travel at just above road level. The width of gap
which causes this behaviour is currently unknown.
Flying up and down linear features on the roadside, but on the side away from the
road.
Using the same routes to reach locations when vegetation is removed, or a road put
across the flight path, until a decision is made to fly a different way. The length of
time which needs to pass before a different path is chosen is currently unknown.
Information on distances travelled by bats between roosts and feeding areas varies from 2km
to 22km in one night depending on the age and sex of the bat. One male bat in North Wales
has been recorded during a radiotracking study flying 4 times between a roost and hibernacula 10km apart, in one evening. There is some evidence that while at the maternity roost
females travelled between 2km and 5km to feed; and juveniles around 1km to 2km.
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3 MITIGATION CASE STUDIES
The following 11 case studies are provided to give examples of the more interesting mitigation measures which we have undertaken. There are of course other techniques available
which are relatively common.
The studies concentrate on the following potential impacts:
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Damage to flight lines between roosting/feeding areas (construction)
Wildlife Vehicle Collisions (operation)
Case Study 1: A465 Heads of Valley Section 1 Abergavenny to Gilwern
Potential Impact
Context of the project
Widening of existing road from 2 lanes (single carriageway)
to 4 lanes (dual carriageway). Open to traffic throughout
construction period.
Maternity roost of c90 individual bats within 300m of project.
Bats regularly flew under and possibly over existing road at
various locations to reach feeding and other breeding areas. Roost believed to be connected to Natura 2000 site
2km away.
Creation of lesser horseshoe bat feeding habitat from a
grazed field, by slowing down of stream, excavation of
shallow pond, managing grass area to be become more
bat friendly (eg: allow flowering plants to flower before
cutting) and planting of insect friendly shrubs and
trees.
Area: approximately 2.2ha
Completed in 2008
Concerns that mitigation measures elsewhere would not
create enough mitigation to cover the significance of the
effects, therefore decision made to create area between
road and roost to provide a new feeding area. The location
it was hoped would reduce the need for bats to cross over
the road to feed
Annual monitoring so far shows slow uptake in the use of
the area for feeding (1 or 2 individuals per year from none
at all).
Context for bats
Description of measure undertaken
Why undertaken
Results of monitoring
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Photograph: Excavating shallow pond. Jacobs
Case Study 2: A465 Heads of Valley Section 1 Abergavenny to Hirwaun
Potential Impact
Context for bats
Description of measure
undertaken
Damage to flight lines between roosting/feeding
areas (construction) and Wildlife Vehicle Collisions
(operation).
Widening of existing road from 2 lanes (single carriageway) to 4 lanes (dual carriageway). Road above
open to traffic throughout construction period.
Maternity roost of c90 individual bats within 300m of
project. Bats regularly used the existing vehicular underpass at Hopyard (4.2m high, 3.5m wide, 18.5m
long) – c 120 - 200 individual movements recorded
over one night. Roost believed to be connected to
Natura 2000 site 2km away.
Extension of existing Underpass which was being
used by Lesser Horseshoe Bats, during the construction period. Extended culvert 2.4m by 2.4m,
with existing culvert total length 67m.
Construction of extension phased to be carried out
during winter seasons when bats not flying and
when other flight paths under the road were not being altered.
Plastic guide fencing applied to ensure that bats
were able to find the underpass.
Work period between 2006 and 2008.
(see also Case study 3)
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Why undertaken
Decision made to remove traffic from underpass and to
keep it purely for bats due to numbers of bats using the
underpass and closeness of the underpass to the
roost. Also a new route for traffic had been provided.
There was a risk that work to extend the underpass
during construction could stop or reduce the use of the
underpass by the bats.
Ongoing. Monitoring (2006 onwards) carried out on the
basis of being similar to original baseline surveys
(2004/5). Bats continued to use the underpass broadly
as before. Occasionally small alterations to numbers of
bats using the underpass occurred which are probably
not related to works being carried out. See also Case
Study 3.
Photograph: underpass
during construction. Jacobs
Case Study 3: A465 Heads of Valley Stage 1 Abergavenny to Hirwaun
Potential Impact
Context of the
project
Context for bats
Description of
measure undertaken
Wildlife Vehicle Collisions (operation); and health and safety
of humans.
Widening of existing road from 2 lanes (single carriageway) to 4
lanes (dual carriageway). Open to traffic throughout construction
period.
Maternity roost of c90 individual bats within 300m of project. Bats
regularly used the Underpass at Hopyard – c 120 - 500 individual
movements recorded over one night. Roost believed to be connected to Natura 2000 site 2km away.
Installation of grilles in Hopyard Underpass to stop humans
accessing the underpass, other than for maintenance.
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Why undertaken
To limit human access to tunnel to prevent damage occurring,
while allowing bats through. Original proposal for metal angled
grille at entrances of underpass made the bats to turn away and a
small number to fly over the road at low level. Tests of types of
grilles and location for the grilles within the tunnel carried out, by
placing wooden frames at various distances from either end.
Vandalism of frames forced decision to put final metal (type of
metal) grilles at c1m from the tunnel entrances in 2009.
Final grille dimensions:
Bars 25mm diameter; vertical spacing between bars at top of
grille 1.2 m; and horizontal spacing between supports 130mm.
Ongoing. With the final grille and full set of bars in place, majority
of bats turned away and went out of the tunnel. When one bar of
the grille removed (see photo) bats passed through. Experiment
in 2010 to see if bats will get used to full set of bars.
Photograph:
New grille with
bar removed.
TACP
Case Study 4: A477 Sageston to Redberth Improvement
Potential Impact
Damage to flight lines between roosting/feeding areas (construction) and Wildlife Vehicle Collisions (operation).
Context of the
project
New single carriageway to remove traffic from two villages.
Context for
bats
Road crosses flight routes to and from roosts and feeding areas.
Numbers using routes relatively low at 2 individuals, but routes also
used by up to 4 individuals of rarer Greater Horseshoe bats (Rhinolophus ferrumequinum).
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Description of
measure undertaken
Why undertaken
Installation of “Armco” culverts during construction in 2001 –
2.2m and 2m in diameter on exact flight paths, and 1 to 2m
above ground level. Culvert size chosen as maximum size
possible which could be installed. Embankment excavated to
form entrance and shrubs planted to link into surrounding
countryside.
Risk of bat casualties became apparent when construction period
surveys highlighted more use of flight lines than originally thought.
Flight lines in culvert locations were across a new embankment,
one culvert at an angle to the line of the road.
Monitoring period 2001 – 2003. Majority of bats used underpasses
almost immediately; one still flew over road. No road casualties
recorded during survey periods. Please note small number of bats
involved.
Photograph:
2m diameter
underpass in
2006. Hyder
Case Study 5: A479 Talgarth Relief Road
Potential Impact
Context for bats
Damage to flight lines between roosting/feeding areas
(construction) and Wildlife Vehicle Collisions (operation).
Single carriageway bypass and improvement of existing road to
remove traffic from centre of town. At location of bat crossing single carriageway and extra lane uphill.
Maternity roosts found in old hospital and farms around the
town, main flight path connecting roosts discovered to be “circu11
Description of
measure undertaken
Why undertaken
lar” around town using woods, hedgerows and large trees; and
a river. New road crosses flight path where 10 to 17 bat movements using a flight path either along stream through existing
culvert or across crowns of mature trees.
Provision of new culvert (dimensions 2.5m) 15m from existing culvert (dimensions 0.9m). New culvert built outside of
bat flight period winter 2006/7 and kept open during bats
flight periods 2007.
Need to maintain flight path after removal of hedgerow with mature trees. (See also Case study 6). Existing underpass also
used by otters (Lutra lutra), badgers (Meles meles).
Monitoring ongoing since 2006. At first bats split between flying
through culverts and also through trees. Removal of branch
from tree nearest road in winter 2007/8 moved all bats to use
culverts. Results during and post construction (so far) suggest
pathway remained in use in similar frequency and numbers as
before.
Photograph:
Existing culvert.
Hyder.
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Case Study 6: A479 Talgarth Relief Road
Potential Impact
Context for bats
undertaken
Why undertaken
(construction)
Single carriageway bypass and improvement of existing road
to remove traffic from centre of town. At location of bat crossing - single carriageway and extra lane uphill.
Maternity roosts found in old hospital and farms around the
town, main flight path connecting roosts discovered to be “circular” around town using woods, hedgerows and large trees;
and a river. New road crosses flight path where 10 to 17 bat
movements using a flight path either along stream through
existing culvert or across crowns of mature trees.
Temporary Construction Fencing*. Plastic fencing on
metal frames moved away from the site during the day
and returned to position at night during the bats flight
period. Fencing along 40m gap between new culvert and
the vegetation left in place.
Risk that bats will not use flight route as no vegetation to follow or to offer protection from predators (eg: birds of prey,
owls etc).
Monitoring in 2006/7 showed that bats continued to use route
with a similar frequency as before construction.
Photograph: Temporary
fencing in place. Hyder.
* it should be noted that some UK advisors do not agree with providing temporary construction fencing. Consideration needs to be given to individual circumstances.
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Case Study 7: A487 Llanwnda to South of Llanllynfi Improvement
Potential Impact
Context for bats
undertaken
Why undertaken
(operation).
Single Carriageway provided to bypass three villages.
Main roost 2.1km away is a Natura 2000 site. Surveys
during construction (2001) found more bat activity than
expected in a number of locations across the road. Radiotracking (2002/2003) confirmed that bats travelling
across road using hedgerows/trees to feeding areas,
and roosting and hibernacula sites.
Bollard/Vertical road side lighting*. Type: Holophane Denver 18W to 24W compact fluorescence.
Temporary lighting trialled in 2002, final installation
2003. Planting and fencing also put in at bottom of
embankment along a diverted stream to guide bats
to the alternative crossing point. Planting was already on the embankment when the lights were installed.
Construction surveys in 2001 found new embankment
had been located on a flight line for 20 to 84 bat
movements, rather than the 2 movements recorded
previously. 6 lesser horseshoe bat casualties found
within first year as bats were following the shape of
embankment.
Surveys ongoing since 2001. Numbers of movements
at crossing point reduced to zero by end of 2003; with
increase in activity at nearby bridge (Bethesda Bach
Bridge) and in flight lines further away from crossing
point (see Case Study 9). In 2007 major vandalism of
the bollards created dark corridor, occasional surveys
showed that bats did not return to the light. Casualty
surveys carried out on a daily basis between midAugust and end of October/November each year (except 2006) shown no further casualties at the original
crossing point.
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Photograph: Bollard light
during the day. 2005. L
Wyatt
* Our approach is to use lighting as a last resort, after considering other options. Concerns
have been raised that diverting flight lines of bats too far, may have impact on energy requirements of bats, although evidence to support or reject this is not available at present.
Case Study 8: A487 Llanwnda to South of Llanllyfni Improvement
Potential Impact
Context for bats
undertaken
(operation).
Main roost 2.1km away is a Natura 2000 site. Surveys
during construction (2001) found more bat activity than
expected in a number of locations across the road. Radiotracking (2002/2003) confirmed that bats travelling
across road using hedgerows/trees to feeding areas,
Fencing at 2m and 4m height. 2m height with single
and double extensions to stop bats crossing the
road. Installed 2001/2.
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Why undertaken
Around 1 to 8 movements per survey event had been
made of bats continuing use 2 flight paths even though
a new culvert (2m diameter) and new vegetation had
been put into place. Approximately 1 to 2 casualties
each year during 2001/2 in two locations.
Did not work.
Bats adjusted flight to return to ground level after flying
up, around and over fencing. Number of movements of
bats in the area remain similar to the original situation
(1 to 8 movements), with occasional casualties (1 to 3
in various years since). Difficult (if not impossible) to
install any further mitigation at these locations, other
than reinforcing and managing planting to guide bats to
new culvert.
Photograph: 2m high fencing with extensions. L Wyatt
Case Study 9: A487 Llanwnda to South of Llanllyfni Improvement
Potential Impact
Wildlife Vehicle Collisions (operation).
Context for bats
Main roost 2.1km away is a Natura 2000 site. Surveys during construction (2001) found more bat activity than expected in a number of locations across the road. Radiotracking (2002/2003) confirmed that bats travelling across
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undertaken
Why undertaken
road using hedgerows/trees to feeding areas, and roosting
and hibernacula sites.
“Ski Jump” consisting of an earth bank and large
trees provided within grass area on one side of the
road. (2004). See also Case Study 10.
Up to 39 movements at this point each year since construction with only one casualty in 2003 so far. However,
casualties at other nearby locations with fewer movements
and consideration of the existing vegetation pattern at this
location (see photograph), suggested that this point could
be managed to become the preferred crossing point in the
longer term.
Monitoring since 2001 shows that number of movements
at this location has dropped to between 2 and 12, possibly
due to wet summers in 2007/8/9. Casualties limited at this
location, but still occur at other locations nearby. Bats
found to use ski jump then drop down to fly at ground level
– see also Case Study 10.
Photograph:
View from gap in hedge
towards Ski Jump and
across road
L Wyatt
Case Study 10: A487 Llanwnda to South of Llanllynfi Improvement
Potential Impact
Damage to flight lines between roosting/feeding areas (construction) and Wildlife Vehicle Collisions (operation).
Context of
Single Carriageway to bypass three villages
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the project
Context for
bats
Description
of measure
undertaken
Why undertaken
Results of
monitoring
Main roost 2.1km away is a Natura 2000 site. Surveys during construction (2001) found more bat activity than expected in a number of
locations across the site. Radiotracking (2002/2003) confirmed that
bats travelling across road using hedgerows/trees to feeding areas,
T shaped bat bridge. Clearance from road 5.7m. Dimensions of T
shape 2m by 2m. Wire mesh size 50mm x 50mm. T shape and
detailed design chosen on advice of bat and bridge specialist
advice. Installed January 2010.
Up to 39 individuals each year crossing at this point. “Ski jump” (Case
study 9) not sufficient to make bats fly over top of traffic. Existing
vegetation on both sides of the road suggested link could be restored.
None so far. Started in April 2010.
Photograph:
Bat Bridge,
Jan 2010,
G Billington
Case Study 11: A487 Porthmadog to Tremadog Improvement
Potential Impact
(construction) and Wildlife Vehicle Collisions (operation).
Provides bypass of town and two surrounding villages at
single carriageway standard. Sensitive landscapes and
international and national sites throughout the area.
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Context for bats
Bypass within 75m of roost of c420 individuals.
undertaken
Vegetated bridge, with fencing and planting to funnel
bats, on exact line of existing flight path. Indicative
design of the bridge requires it to be 7m wide and
40m long with 1.8m high solid parapets (sides) to
provide a dark corridor. Large planting boxes and upturned tree stumps, soil and branches from vegetation clearances will be laid out across the bridge.
Detailed field survey (2004 to 2009) and radiotracking of
females and juveniles (2005) had confirmed importance
of movements from the roost across road at 5 locations.
Most flight paths will have >2.5m underpasses for the
bats to fly through aligned on the original flight paths.
However, this flight path is over a cutting/valley. Considering the importance of the flight path (c 100 movements
per night) the decision was made to provide it for bats
only, although attempts were made to find another suitable non-bat use for the bridge which would have made
the reasons for the bridge stronger.
Construction has recently started. Construction monitoring due to start soon.
Why undertaken
Photograph: Design of
proposed bridge. Halcrow.
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4 SURVEYING CONSIDERATIONS
Our published advice (Highways Agency et al, 2008, Nature Conservation Advice in relation
to Bats) which covers all bat species, states that surveys should provide sufficient information to find out:
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Which bat species are present
Where they roost and forage at different times of the year
What routes they use to travel between roosts and foraging areas within the
immediate vicinity of the road/structure/tree/building concerned; and
How the project will impact on the bats and what mitigation can be included to
reduce the significant effects.
Critical to this is the scoping of the surveys (setting out and agreeing the details of the locations, timing and methodologies to be used to carry out the surveys); and also having the
ability to review the scope of surveys during the survey period, in case changes need to be
made.
Generally, surveys will consist of reviews of existing information and field based surveys.
For lesser horseshoe bats on our large scale projects with significant effects on flight lines,
we do recommend that a full season’s surveys of flight lines (eg: from late April/May to September) are carried out.
The intensity of those surveys over the season depends on the potential significance of effects of the project; and on the technology used. When using hand held bat detectors consideration should be made of surveying on two consecutive nights each month over the season.
When automated detectors are used, this may be reduced, but consideration has to be given
to the location and characteristics of the recorders. Special consideration is usually given in
these surveys to recording how the bats fly across the road (eg: height and location).
In some cases where projects have been delayed, we have kept the survey information up to
date with ongoing surveys, as it is possible that overtime the use of the area by lesser horseshoe bats, or the population of the bats in the area changes. This is done so that any significant, and potentially long term changes can be identified early (eg: changes in flight lines,
use of areas, or even failure of maternity roosts/hibernacula) and dealt within the design and
assessment process.
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5 DESIGN CONSIDERATIONS
The aim of all of our design advice is to encourage a holistic and integrated approach to the
way environmental issues are dealt with within the design and assessment processes we
use. Examples of this would be the consideration of the design of a bat bridge within a sensitive landscape area; or the design of a road drainage scheme and its effects on bat flight
paths and feeding areas.
Experience has taught us that we need to ensure that:
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Relevant designs are brought forward which are cost effective, and meet the
requirements of legislation and guidance
There is close cooperation between engineers, ecologist and bat specialist as
a good understanding of the actual situation and implications of mitigation is
critical for those working on solutions.
That liaison with relevant organisations with responsibility for bats is carried
out.
Understanding the context of the project and the bats is an extremely important consideration.
6 MONITORING CONSIDERATIONS
Our guidance states that monitoring is:
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Vital to provide data on the success or failure of measures
Vital to increase our understanding of the use of roads by bats;
And that it should be:
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Appropriate to the mitigation provided
Agreed with the relevant parties
I would add that monitoring should be included in the contract requirements to ensure that it
is taken forward.
For most of the projects here, there have been surveys to inform a baseline before the
scheme is started (either during the design process or just before construction), which then
informs the monitoring carried out during and after construction in terms of locations and survey effort. Bat casualty monitoring after construction have been usually considered on a case
by case basis, depending on a judgement of whether there is a high risk of failure of mitigation measures causing road casualties.
From experience we have found that it can be difficult to isolate the effects or changes potentially caused by the road on movements and populations, and those caused by non-road
21
sources (eg: bad weather, changes in sizes of roosts, physical changes to the roost itself, or
where a large roosts split into two).
7 CONCLUSIONS
The paper has described the context in which the Welsh Assembly Government undertakes
its work with Lesser Horseshoe Bats and large new road projects.
It is true to say that our knowledge since the beginning of the century has improved, and we
are now able to refer to examples of successful mitigation to support the application of mitigation in new circumstances after considering the context involved. However, some measures which have been applied have had to be based on best professional judgement of the
situation involved, and only monitoring will tell whether they are effective.
We are hoping to:
•
•
•
•
Continue to learn from our experiences, and the experience of others in similar situations.
Continue to improve the ability of engineers, ecologist and bat specialists to
understand the issues involved, and develop practical solutions to avoid, reduce or if possible remedy effects.
Improve the way we understand context of the projects and the use of the surrounding areas by bats
Improve the way we undertake Environmental Impact Assessment and “Appropriate Assessment”/Assessment of the Implications on European Sites.
8 FURTHER UK BASED INFORMATION
Please note that not all of the references are specifically written for the road situation. Those
that are have a * next to them.
Bat Conservation Trust, 2007, Bat Surveys Good Practice Guidelines, Bat Conservation
Trust. ŚƚƚƉ͗ͬͬǁǁǁ͘ďĂƚƐ͘ŽƌŐ͘ƵŬͬƉƵďůŝĐĂƚŝŽŶƐ͘ƉŚƉ
*Bickmore, C, 2003, Review of work carried out on trunk road network in Wales for bats,
Welsh Assembly Government and Countryside Council for Wales – from
ŚƚƚƉ͗ͬͬǁĂůĞƐ͘ŐŽǀ͘ƵŬͬƚŽƉŝĐƐͬƚƌĂŶƐƉŽƌƚͬƌŽĂĚƐͬĞŶǀŝƌŽŶŵĞŶƚͬƌĞƐĞĂƌĐŚƌĞƉŽƌƚƐ͍ͬůĂŶŐсĞŶ or author
Entwhistle, A et al, 2001, Habitat Management for Bats – A guide for land managers, land
owners and their advisors, JNCC,
*Highways Agency et al, 2008, Design Manual for Roads and Bridges – Interim Advice Note
– Nature Conservation Advice in relation to Bats 116/08
English version – ŚƚƚƉ͗ͬͬǁǁǁ͘ƐƚĂŶĚĂƌĚƐĨŽƌŚŝŐŚǁĂǇƐ͘ĐŽ͘ƵŬͬŝĂŶƐͬŝŶĚĞǆ͘Śƚŵ
22
Wales version –
ŚƚƚƉ͗ͬͬǁĂůĞƐ͘ŐŽǀ͘ƵŬͬƚŽƉŝĐƐͬƚƌĂŶƐƉŽƌƚͬƌŽĂĚƐͬĞŶǀŝƌŽŶŵĞŶƚͬŝĂŶƐͬƉƵďůŝƐŚĞĚŝĂŶƐ͍ͬůĂŶŐсĞŶ or from Author
Mitchell – Jones AJ, 2004, Bat Workers Manual (3rd Edition), JNCC
Schofield, H, 2009, Lesser Horseshoe Bat Conservation Handbook, The Vincent Wildlife
Trust
Other UK National Highway Authority contacts:
•
•
England - Stuart Wilson, Highways Agency – ƐƚƵĂƌƚ͘ǁŝůƐŽŶΛŚŝŐŚǁĂǇƐ͘ŐƐŝ͘ŐŽǀ͘ƵŬ
Northern Ireland – Stephen Tweed , Roads Service –
^ƚĞƉŚĞŶ͘ƚǁĞĞĚΛĚƌĚŶŝ͘ŐƐŝ͘ŐŽǀ͘ƵŬ
•
Scotland – Angus Corby, Transport Wales –
ŶŐƵƐ͘ĐŽƌďǇΛƚƌĂŶƐƉŽƌƚƐĐŽƚůĂŶĚ͘ŐƐŝ͘ŐŽǀ͘ƵŬ
9 ACKNOWLEDGEMENTS
1 Contractors and Consultants for case study information and photographs:
Mowlems/TACP/Gwynedd Council/Greena Ecology – A487 Llanwnda to South of Llanllynfi
Improvement
BAM Nuttall/TACP/Jacobs – A465 Heads of Valley Dualling Section 1
Jacobs – A465 Heads of Valley Dualling Section 2
Halcrow/WYG – A487 Porthmadog to Tremadog Improvement
BAM Nuttall/Hyder/WYG/Just Mammals – A479 Talgarth Relief Road
BAM Nuttall/Arup/Hyder/Cresswell Associates – A477 Sageston to Redberth Bypass
2 For comments on the paper:
Stuart Wilson, Highways Agency
Jean Matthews, Countryside Council for Wales
23
3 Finally, I would like to thank to all the Welsh bat groups, and individual engineers and bat
workers who while not mentioned above, have assisted with increasing our understanding of
the issues we are facing and developing solutions.
Len Wyatt CEnv MIEEM
Environment Science Advisor,
Telephone: 044 (0)2920 82 6780
Transport and Strategic Regeneration,
Email: [email protected]
Welsh Assembly Government,
Cathays Park
Cardiff, Wales, UK, CF10 3NQ
24

1 1 INTRODUCTION This paper has been prepared to support a

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