Page | 1 The Cotswold Water Park Bat initiative The Bat Assemblage of the Cotswold Water Park An analysis of data collected 2005 to 2013 A project of the Cotswold Water Park Biodiversity Action Plan (2007‐2016) May 2014 Gareth Harris Cotswold Water Park Bat Initiative The Cotswold Water Park Bat Initiative: The Bat Assemblage of the Cotswold Water Park Gareth Harris, Ecology & Conservation (March 2014) Page | 2 Acknowledgements Funding for the CWPBI has come from a variety of sources over the year; much of this support has come from the Lower Mill Estate section 106 (administered by Cotswold District Council) and indeed the latest support of this project has funded the publication of this mini‐atlas. Once again, Lower Mill Estate and Cotswold District Council are thanked for their unwavering support. The additional organisations and individuals who have financially supported this project are also thanked; Cotswold Water Park Trust, Gloucestershire Bat Group, Wiltshire Bat Group, Gloucestershire Naturalists Society, Gloucestershire Environmental Trust Company (GETCO), Aggregates Levy Sustainability Fund, Mr Will Ponting and Mr Richard Chappell. All of the landowners and house holders who have supported the project over the year are also thanked for their support, involvement, help and interest and for safeguarding the roosts and bat habitats discovered with them. You are too numerous to list here and may have requested anonymity, but you know who you are. The many volunteers who have supported the project, since the beginning are also thanked; the complete list is too long, but a number have shown particular dedication to this project since the beginning; Will Ponting & Jenny Ford helped establish this project in the beginning, Lisa Wade, Eric Palmer, Emily Castell, Dr Nick Downs, Dr Dani Linton, Ben Welbourn, Kate Kibble, and many more! A number of dedicated experts have shared their knowledge and expertise with this project and its volunteers through a series of training events; Dr Fiona Mathews, Dr Sandie Sowler, Dr David Bullock, Dr Jude Smith, Daniel Whitby, Daniel Hargreaves, Dr Dani Linton, Henry Andrews and David Endacott. Thank you to you all. Earlier drafts of this document were improved following contributions from Jenny Bennett, Purgle Linham, Eric Palmer and Will Ponting. All are warmly thanked. Any remaining errors are my own. This document is written on behalf of all of these contributors. Suggested citation; Harris, G. et al (2014). The Bat Assemblage of the Cotswold Water Park; an analysis of data collected 2005 to 2013. The Cotswold Water Park Bat Initiative. May 2014. All maps were produced by the WSBRC and contain Ordnance Survey data © Crown Copyright and database right 2014. Purgle Linham is warmly thanked for her GIS expertise in producing the maps in this publication. The Cotswold Water Park Bat Initiative: The Bat Assemblage of the Cotswold Water Park Gareth Harris, Ecology & Conservation (March 2014) Page | 3 Contents 1. Introduction 4 1.1 About this report 4 1.2 The Cotswold Water Park 4 1.3 Indication of the potential importance for bats 5 1.4 The Cotswold Water Park Bat Initiative 5 1.5 The Braydon Forest 6 1.6 The study area 7 1.7 Volunteers, surveyors, trainers and supporters 8 1.8 Licensing 8 2 Methodology 10 2.1 Transect surveys 10 2.2 Trapping surveys 10 2.3 Bat box surveys 10 2.4 Static detector surveys 11 2.5 Surveys of buildings including barns and churches 11 2.6 Bridge Surveys 11 2.7 Roost surveys, visits and monitoring & local communities 12 2.8 Radiotracking 12 3 Introduction to the Species Accounts 13 3.1 Records: numbers and record types 13 3.2 A checklist of species recorded in the CWP to date 13 3.3 Summer roosting bats 14 3.4 Hibernating bats 15 3.5 Identification to genus or species level 16 3.6 Introduction to the species accounts and maps 16 3.7 All species 17 4 Species Accounts 19 4.1 Greater Horseshoe bat 19 4.2 Lesser Horseshoe bat 21 4.3 Whiskered bat 23 4.4 Brandt’s bat 25 4.5 Whiskered / Brandt’s bat 27 4.6 Natterer’s bat 29 4.7 Bechstein’s bat 32 4.8 Daubenton’s bat 35 4.9 Unidentified Myotis bats 38 4.10 Serotine bat 39 4.11 Noctule bat 41 4.12 Common Pipistrelle bat 44 4.13 Soprano Pipistrelle bat 47 4.14 Nathusius’ Pipistrelle bat 50 4.15 Barbastelle bat 53 4.16n Brow Long‐eared bat 55 5 Recommendation for bat conservation in the CWP 58 5.1 Threats & opportunities to bat habitats in the Cotswold Water Park 58 5.2 General recommendations for bat conservation in the CWP & Braydon Forest 64 5.3 Summary of recommendations by species: future surveys and research 67 References 71 Appendix:s Bat Specie Action Plan, Cotswold Water Park Biodiversity Action Plan (2008‐2016) 73 The Cotswold Water Park Bat Initiative: The Bat Assemblage of the Cotswold Water Park Gareth Harris, Ecology & Conservation (March 2014) Page | 4 1. Introduction 1.1. About this report This report provides an analysis of the first nine years of the Cotswold Water Park Bat initiative (CWPBI). As such it may be considered to be a “mini‐atlas” of bats in the CWP combined with an interim report of work to date; it is very much a work in progress. For each species recorded in the CWP, we provide a species account, a series of maps, a statement of our current knowledge and recommendations for further survey and conservation work. We do not presume that the project has completed its original aims but what we have achieved so far provides an excellent baseline upon which to base further work and to prioritise future conservation action. 1.2. The Cotswold Water Park The Cotswold Water Park (CWP) comprises 40 square miles of wetlands and farmland at the head of the Thames Valley. Straddling four county boundaries, the CWP lies mainly in Gloucestershire and Wiltshire, but also in Oxfordshire and Swindon Borough. Large deposits of minerals were deposited as ice sheets retreated during previous Ice Ages; much of the resulting sand & gravel was carried by a once‐larger river (today’s River Thames), depositing this material throughout the Thames Valley in a series of exploitable terraces. Gravel extraction over the past 50 years has created 154 lakes of varying sizes so far. A further 30‐50 years' worth of extraction may remain, ensuring that extensive areas of new wetlands will be created in the future. The CWP is already 50% larger than the Norfolk Broads and is set to become one of the largest areas of man‐ made wetland in Europe. The high invertebrate abundance in the lakes and other wetland habitats, coupled with the rich aquatic plant assemblage indicates high water quality. Indeed, the crystal‐clear lime‐rich marl waters support a rich aquatic plant assemblage considered to be of European Importance, in particular for the assemblage of Stoneworts and Potamogeton pondweed species. Ten lakes have been designated as Sites of Special Scientific Interest (SSSI) for their aquatic plant interest. The newly‐created wetlands have attracted an ever‐increasing number of other species dependent on the high quality water environment. The area attracts 35‐40,000 wintering waterbirds and is internationally important for Lesser Black‐backed Gull, nationally important for several species including Pochard, Tufted Duck, Gadwall, Shoveler, Coot, Great Crested Grebe and Smew. Furthermore, surveys in 2007 suggest the area supports a summer waterbird population of 6,568 – 7,704 birds, including nationally important breeding populations of six species of waterbird (Coot, Great Crested Grebe, Mute Swan, Tufted Duck, Red Crested Pochard and Gadwall)1. The CWP supports a wide diversity of wildlife, including significant populations which existed prior to mineral extraction. In addition to bats, which are the subject of this review, the CWP supports important farmland bird populations such as Tree Sparrow, Lapwing, Yellow Wagtail and Barn Owl, mammals such as Otter and Water Vole. Following intensive control of American Mink in recent years, remnant water vole populations are flourishing once more and recovering their range across the CWP. Similarly Otter populations continue to thrive following a recent recovery and may be recorded using all of the watercourses across the area. Traditional hay meadows support many thousands of green‐winged orchids and snakes‐head fritillaries. Six neutral grasslands have been designated SSSI’s, including some of the finest hay meadows remaining in Europe, such as the internationally‐renowned Special Area of Conservation, 1 Adams N, Harris G 2008. Breeding Waterbird Surveys of the Cotswold Water Park 2007. Part of the CWP BAP Implementation Project. Cotswold Water Park Society & Royal Society for the Protection of Birds The Cotswold Water Park Bat Initiative: The Bat Assemblage of the Cotswold Water Park Gareth Harris, Ecology & Conservation (March 2014) Page | 5 Clattinger Farm (owned and managed by Wiltshire Wildlife Trust) & North Meadow National Nature Reserve SSSI (managed by Natural England). 1.3. Indications of potential importance for bats Many of the lakes are relatively new and are yet to develop a mature fringe of vegetation; such lakes may be devoid of dense stands of vegetation and adjacent tree growth and are consequently exposed to the elements and frequently less attractive to foraging bats except on all but the calmest of evenings. Many of the lakes however have developed a rich assemblage of aquatic plants, submerged in the lake or growing around or on the margins. Such vegetation supports a diverse abundance of insects. Many of the lakes yield a super‐abundance of invertebrates such as damselflies, caddis flies and mayflies during mass emergences from the lakes noted throughout May and into June.