Experiences of dealing with Lesser Horseshoe Bats (Rhinolophus

Transcription

1 Experiences of dealing with Lesser Horseshoe Bats (Rhinolophus hipposideros) in Wales, UK Len Wyatt Environmental Science Advisor, Transport, Housing and Strategic Regeneration, Welsh Assembly Government, UK Bats and Road Planning, Köln, Germany. June 2010 Bats and Road Planning, Koln, Germany. June 2010

2 The Presentation 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 - Welsh Assembly Government Working Together for Wales

3 Aim To explain the context in which the Welsh Assembly Government works. To provide information on some of the mitigation measures for Lesser Horseshoe Bats (Kleine hufeisennase) 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. Welsh Assembly Government Working Together for Wales

4 The Context 1 Our Network 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. Welsh Assembly Government Working Together for Wales

5 Views of our network

6 The Context 2 Lesser Horseshoe Bats in the UK 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. Welsh Assembly Government Working Together for Wales

7 Locations where we have found lesser horseshoe bats Dia 1.5m In bridges like this one

8 The Context 3 Lesser Horseshoe Bat flight behaviour 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. Welsh Assembly Government Working Together for Wales

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10 Case Studies 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. Welsh Assembly Government Working Together for Wales

11 Case Studies: 1,2 and 3 A465 Section 1 Abergavenny to Hirwaun

12 Case Studies 1,2 and 3 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 Welsh Assembly Government Working Together for Wales

13 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 Case Study 1 New habitat Monitoring so far shows slow uptake in use of area. 1 or 2 individuals per year. Welsh Assembly Government Working Together for Wales

14 Excavating shallow pond Planting new trees/shrubs

15 Case Study 2 Extended underpass 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 c individual movements recorded over one night before construction. Monitoring showed similar numbers of movements, with occasional small alterations, probably not related to the road. Welsh Assembly Government Working Together for Wales

16 4.2m To roost 3.5m Before construction

17 During construction note replacement trees Width of new culvert 2.4m

18 Case Study 3 Grilles in underpass 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 Monitoring found bats confused by grilles two bars taken out, passed through safely. Will the bats get used to bars in 2010? Welsh Assembly Government Working Together for Wales

19 c.1.2m 130mm With all 2.5mm dia bars in currently fewer bats go through.how long before they learn?

20 Case Study: 4 A477 Sageston to Redberth Improvement

21 Case Study 4 New bat underpasses 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 Majority of bats used underpasses although one few over road. No road casualties recorded during survey period. Welsh Assembly Government Working Together for Wales

22 2.2m elliptical Please note small sample size in surveys

23 2m elliptical Please note small sample size in surveys

24 Case Studies: 5 and 6 A479 Talgarth Relief Road

25 Case Studies 5 and 6 New underpass and construction fencing 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) Welsh Assembly Government Working Together for Wales

26 Case Study 5 New underpass 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 Monitoring ongoing since 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. Welsh Assembly Government Working Together for Wales

27 Existing culvert 0.9m wide

28 New culvert, with existing culvert in background 2.5m dia

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

30 Case Study 6 Construction fencing 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. Welsh Assembly Government Working Together for Wales

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

32 Case Studies: 7,8,9 and 10 A487 Llanwnda to South of Llanllynfi Improvement

33 Case Studies 7, 8, 9 and 10 Bat flight line measures Single Carriageway to bypass three villages Main roost 2.1km is a Natura 2000 site. September 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). Welsh Assembly Government Working Together for Wales

34 Case Studies 7 Bollard lighting 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 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. Welsh Assembly Government Working Together for Wales

35 Bollard lights on both sides of road

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

37 Case Study 8 Fencing to block flight lines 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. Welsh Assembly Government Working Together for Wales

38 4m fencing

39 2m high fencing with double extensions

40 Case Study 9 Ski jump 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 locations nearby. Bats found to use ski jump then return to ground level see Case Study 10. Welsh Assembly Government Working Together for Wales

41 Cycle way to ski jump

42 ski jump Existing trees other side of road

43 Case Study 10 T bat bridge 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. Welsh Assembly Government Working Together for Wales

44 T shaped bridge. Ski-jump on left hand side of bridge 5.7m clearance

45 Bat bridge in side profile 2m x 2m

46 Case Study: 11 A487 Portmadog to Tremadog Improvement

47 Case Study 11 Vegetated bridge 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. Welsh Assembly Government Working Together for Wales

48 Proposed Overbridge To roost

49 Principles 1 Surveying considerations Provide sufficient information about: Which bat species are present Where they roost and forage at different times of year What routes they use How 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 photos for landscape analysis) and field based surveys Welsh Assembly Government Working Together for Wales

50 Principles 2 Design 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 Welsh Assembly Government Working Together for Wales

51 Principles 3 Monitoring 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). Welsh Assembly Government Working Together for Wales

52 Conclusions 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 Welsh Assembly Government Working Together for Wales

53 Acknowledgements 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 Welsh Assembly Government Working Together for Wales

54 Thank you for listening