Experiences of dealing with Lesser Horseshoe Bats

Bats and Road Planning, Koln, Germany. June 2010

Experiences of dealing with Lesser Horseshoe Bats (Rhinolophus

hipposideros) in Wales, UK

Len WyattEnvironmental Science Advisor, Transport, Housing and Strategic Regeneration, Welsh Assembly Government, UK

Bats and Road Planning, Köln, Germany. June 2010

Working Together for WalesWelsh Assembly Government

• Aim• The Context – Our Network• The Context – Lesser Horseshoe Bats in the UK• The Context – Lesser Horseshoe Bat flight behaviour• Case Studies• Principles 1 – Surveying Considerations• Principles 2 – Design Considerations• Principles 3 – Monitoring Considerations• Conclusions• Acknowledgements

Emphasis on practical measures, general principles and the importance of understanding context.

For all slides bat flight paths are shown by -

The Presentation


• To explain the context in which the Welsh Assembly Government works.

• To provide information on some of the mitigation measures for Lesser Horseshoe Bats (Kleinehufeisennase) we have provided*

• To provide principles which have informed our work

Further details and other information are provided within the paper associated with this presentation.

*Please note – my view is that the measures here may not work in situations where the context is different.

Aim


• Wales covers 20,779 sq km

• Our network is c.1700km

• Majority of network is single carriageway – width of carriageway without verges and hard strips – c7.3m

• There are 2 motorways in South Wales, and the majority of dual carriageways are in north and south Wales.

• In many areas geology and landscape means that network follows river valleys between mountains and hills……the valleys also provide the best areas of Lesser Horseshoe Bats.

The Context 1 – Our Network

Views of our network


• UK Population 15,000 to 24,000 individuals

• About half of UK population is in Wales

• Use a variety of locations for roosts and hibernacula….including bridges, 300mm drainage pipes in road surface (rare?), crevices in rocks (rare?)

• Habitats for feeding – woodland and scrub, vegetated river corridors, grassland/wet grassland close to flight routes or other vegetation

• Features to guide movements – well connected hedgerows/woodland edges, rivers, streams, wire fencing/stone walls……..underpasses and tunnels.

• Large number of legislative requirements from EC and UK have to met before a project can go ahead.

The Context 2 – Lesser Horseshoe Bats in the UK

Locations where we have found lesser horseshoe bats

Dia 1.5m

In bridges like this one


• A reluctance to fly across open areas. Details of how wide a gap can be crossed - unknown

• Avoidance of street lights and lit areas. Details of strength of lighting which will not be avoid - unknown

• Fly high over traffic using tree canopies/crowns – or if not available, will fly between 0.5 and 1.5m above a road.

• Fly up and down linear features – alongside road

• Will use same routes to get to locations. Length of time before will change route if the route is changed – unknown.

The Context 3 – Lesser Horseshoe Bat flight behaviour


• 11 Case studies are presented with the following information:

• Location Map

• General Context of the situation

• Picture/description of the mitigation

• Results of Monitoring

The Case Studies relate to large new infrastructure projects.

Case Studies

Case Studies: 1,2 and 3

A465 Section 1 Abergavenny to Hirwaun


• Widening of existing road (3 lanes) to dual carriageway (4 lanes)

• Maternity roost of c90 individuals with 300m

• Bats flew regularly under and possibly over the existing road to reach feeding and other breeding areas.

• Baseline surveys up to 2004, then ongoing monitoring from 2006

Case Studies 1,2 and 3


• Concern that other mitigation measures were insufficient

• Creation of feeding habitat on roost side of road–by slowing down stream, building shallow pond, managing area for insects and planting of insect friendly shrubs and trees.

• Approximately 2.2ha

• Created 2008

• Monitoring so far shows slow uptake in use of area. 1 or 2 individuals per year.

Case Study 1 – New habitat

Excavating shallow pond

Planting new trees/shrubs


• Concern about risk that existing safe flight path would be affected by extension, and increased risk of collisions with vehicles

• Extension of existing underpass – phased to be carried out during winter season and when other flight paths under the road were not being altered. Plastic guide fencing and trees also installed

• c100 – 120 individual movements recorded over one night before construction. Monitoring 2006 - 8showed similar numbers of movements, with occasional small alterations, probably not related to the road.

Case Study 2 – Extended underpass

3.5m

Before construction

To roost

4.2m

During construction – note replacement trees

Width of new culvert 2.4m


• The new underpass in Case Study 2 needed to be protected from damage and people falling accidently into the tunnel.

• Installation of 2 metal grilles at entrances

• Original location across entrances to underpass installed in 2008 stopped bats completely. Test carried out with wood grilles had to be halted due to vandalism. Final set installed c1m from entrances in tunnel in 2009.

• Monitoring 2009 - found bats confused by grilles –two bars taken out, passed through safely. Will the bats get used to bars in 2010?

Case Study 3 – Grilles in underpass

130mm

With all 2.5mm dia bars in – currently fewer bats go through….how long before they learn?

c.1.2m

Case Study: 4A477 Sageston to RedberthImprovement


• Single carriageway bypass of two villages

• Surveys during construction in 2001 found more bat activity than expected. Risk of loss of flight paths and risk of collisions with vehicles.

• Installation of 2.2m and 2m culverts on exact flight paths. Size chosen as maximum possible to fit in. Embankment excavated to form entrance and shrubs planted to link into surrounding countryside.

• Monitoring 2001-3. Majority of bats used underpasses – although one few over road. No road casualties recorded during survey period.

Case Study 4 – New bat underpasses

Please note small sample size in surveys 2001-3

2.2m elliptical

2m elliptical

Please note small sample size in surveys 2001-3

Case Studies: 5 and 6A479 Talgarth Relief Road


• Single carriageway bypass and improvement of existing road to remove traffic from centre of town.

• Maternity roosts found in an old hospital and farms around the town.

• “Circular” flightpath around the edge of town using woods, hedgerows, large trees and a river.

• Surveys found 10 to 17 individual movements along stream through existing culvert – and through canopy of trees.

• Culvert also used by badger (Meles meles) and otter (Lutra lutra)

Case Studies 5 and 6 – New underpass and construction fencing


• Concerned about damage to flight lines and risk of collisions with vehicles after removal of hedgerow and trees.

• New underpass constructed 15m from existing culvert, outside flight periods in winter 2006/7 and kept open during flight period 2007.

• Monitoring ongoing since 2006. Activity levels similar to before construction.

• At first bats split between culverts and trees. Removal of branch in 2007/8 eventually moved all bats to use culverts.

Case Study 5 – New underpass

0.9m wide

Existing culvert

2.5m dia

New culvert, with existing culvert in background

One of 2 flightlines across or under construction footprint – this one in canopy of trees. Flightlinestopped by removing branch –bats changed to using the other flightline through culverts


• Risk of damage to flightlines during construction

• Plastic fencing on metal frames moved away from site during the day, and returned at night, during the bats flight period.*

• Monitoring in 2006/7 showed similar numbers of bats using route as before construction.

*Some UK advisors do not agree with providing temporary construction fencing. Consideration needs to be given to individual circumstances.

Case Study 6 – Construction fencing

Construction fencing leading from New culvert 2.5m diameter to remaining vegetation. Gap distance c40m.

Case Studies: 7,8,9 and 10A487 Llanwnda to South of LlanllynfiImprovement


• Single Carriageway to bypass three villages

• Main roost 2.1km is a Natura 2000 site. September 2001 – 871 individuals at the roost.

• Surveys during construction 2001 found more activity than expected at a number of locations.

• Radiotracking (2002/3) confirmed bats travelling across the road using hedgerows/trees to feeding areas, and roosting/hibernacula sites.

• Monitoring ongoing since 2001 of flightpaths, mitigation; and casualties (daily between August to November).

Case Studies 7, 8, 9 and 10 – Bat flight line measures


• Monitoring during construction found 20 to 84 bat movements, rather than the 2 recorded before.

• 6 lesser horseshoe bat road casualties found within first year• Trial (2002) and then installation (2003) of Bollard

lighting – Holophane Denver compact fluorescence. Planting and guide fencing also installed at bottom of embankment to guide bats along diverted stream to new bridge.

• Numbers of movements at lighted area – reduced to zero in 2003. Increased movements at bridge and other crossing points. No further casualties at this point.

• Damage in 2007 to bollards created dark corridor –occasional surveys found that bats did not return.

Our approach is to use lighting as a last resort, after considering other options.

Case Studies 7 – Bollard lighting

Bollard lights on both sides of road

Bats diverted by lighting use this bridge and crossing points to the north.


• Surveys during construction had found 1 to 8 movements per survey event in two locations – even though new culvert (2m diameter) and new vegetation in place.

• Approximately 1 to 2 casualties per year during 2001/2 at both locations.

• Installation of 2m and 4m high fencing. 2m high fencing had 1 or 2 extensions added.

• Monitoring quickly showed bats adjusted flights to fly up, around and down the fencing.

Case Study 8 – Fencing to block flight lines

4m fencing

2m high fencing with double extensions


• Following the shift of the flightline by the lighting bollards, numbers of movements at this location increased (up to 39 movements), with only 1 casualty so far (2003). Casualties occurring nearby with fewer movements.

• Bats use of the gap in the trees and the vegetation suggested this crossing point could be made a preferred crossing point in the longer term.

• Earth bank and large trees provided within grass area on one side of road (2004)

• Recent monitoring has shown numbers dropped to between 2 and 12 at this point – wet summers 2007/8/9? Small numbers of casualties at locationsnearby.

• Bats found to use ski jump then return to ground level – see Case Study 10.

Case Study 9 – “Ski jump”

Cycle way to “ski jump”

“ski jump”

Existing trees other side of road


• “Ski-jump” (Case Study 9) was not working.

• Up to 39 individuals per year crossing at this point before decision was made, numbers have since dropped. Casualties at locations nearby.

• Existing vegetation suggested link between vegetation may be a long term option.

• T shaped bridge. Mesh 50mm x 50mm.

• Installed January 2010 – monitoring just started.

Case Study 10 – T bat bridge

T shaped bridge. Ski-jump on left hand side of bridge

5.7m clearance

Bat bridge in side profile

2m x 2m

Case Study: 11A487 Portmadog to TremadogImprovement


• Proposed single carriageway – bypass of town and two villages

• Potential for damage to flight lines• Roost of c420 individuals within 75m of road• Surveys showed c100 movements each night• Road in cutting/valley at this point• Vegetated bridge on exact flightline, with fencing

and planting to funnel bats.• Indicative design – 7m wide, 40m long with 1.8m

high sides• Large planting boxes and upturned tree stumps, soil

and branches from the vegetation clearance to be placed on bridge.

Construction has just started. Construction monitoring to start soon.

Case Study 11 – Vegetated bridge

Proposed Overbridge

To roost


• Provide sufficient information about:Which bat species are present

Where they roost and forage at different times of yearWhat routes they useHow the project will impact on the bats and what mitigation can be included to reduce significant effects

• Agree extent, locations, timing, intensity and methodologies to be used (scoping). Recommend full season (April/May to Sept). Repeat to keep information up to date if project delayed.Review survey if necessary during the survey period.

• Usually consist of review of existing information (aerial photosfor landscape analysis) and field based surveys

Principles 1 – Surveying considerations


• Holistic and integrated design process which is cost effective, and meets the requirements of legislation and guidance.

• Close cooperation between engineers and bat specialists/ecologists – a good understanding across the whole team

• Liaison with relevant organisations with responsibility for bats

• Understanding the context of the project – and the bats is an extremely important consideration

Principles 2 – Design Considerations


• Why monitor – vital to provide data on success/failure; and to increase our understanding

• Monitoring should be appropriate to mitigation provide and agreed with relevant organisations

• Usually monitoring uses baseline before construction for comparison, and is carried out during and after construction.

• Experience has taught us that it can be difficult to isolate effects on bat movements and populations of the road, from non-road sources. (eg: bad weather, physical changes to the roost, change in number of bats, or where roosts split up).

Principles 3 – Monitoring considerations


• We are :• starting to have evidence of whether mitigation

works or not• hoping to continue to learn from our

experiences, and the experiences of others• hoping to continue to improve our ability to

understand issues involved and develop practical solutions

• hoping to improve the way we understand the context of projects and the use of surrounding areas by bats

• improving the way we undertake the required assessments

Conclusions


• Contractors, consultants and individuals who have provided information and photographs

• Countryside Council for Wales and Highways Agency for comments

• Bat workers and engineers who have assisted with increasing our understanding of the issues and developing solutions

Acknowledgements

Thank you for listening……

Documents

Experiences of dealing with Lesser Horseshoe Bats