The effect of roads on bats in the UK: a model for evidence based conservation Anna Berthinussen Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds School of Biology June, 2013 - ii - The candidate confirms that the work submitted is her own, except where work which has formed part of jointly-authored publications has been included. The contribution of the candidate and the other authors to this work has been explicitly indicated below. The candidate confirms that appropriate credit has been given within the thesis where reference has been made to the work of others. Chapters 2 and 5 are based on the following jointly-authored publications: Berthinussen, A. & Altringham, J. (2012) The effect of a major road on bat activity and diversity. Journal of Applied Ecology, 49, 82-89. Berthinussen, A. & Altringham, J. (2012) Do bat gantries and underpasses help bats cross roads safely? PLoS ONE 7, e38775. In both publications Anna Berthinussen and John Altringham designed the experiments. Anna Berthinussen performed the experiments, analyzed the data and wrote the first draft of the paper. John Altringham and Anna Berthinussen both made edits to later drafts. University of Leeds students assisted with field work and acknowledgements are given where due. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. © 2013 The University of Leeds and Anna Berthinussen - iii - Acknowledgements First and foremost, I would like to thank my excellent supervisor, John Altringham, for his support, guidance and enthusiasm. His faith in me has allowed my confidence to grow, and he has taught me a great deal about research, and the importance of sticking to your guns and being assertive! I would also like to thank the rest of the bat group (Anita Glover, Chloe Bellamy, Chris Scott, Claire Wordley and Emma Grubb) for their friendship and advice throughout my PhD. It has been a pleasure to work with such a great team, and I have many memories that I will cherish. I owe thanks to the students, volunteers, friends and family that assisted me in the field; David Bodenham, Tom Appleby, Emily Forbes, Nithya Xavier, Megan Resse, Chrissie Webster, Liane Hobson, Iroro Tanshi, Elizabeth Mason, Rebecca Copley, Reece Fullford and Carol Hazell. Their help, hard work and enthusiasm have been invaluable, and I look back fondly on the adventures we shared together in Cumbria, Northumberland and Somerset. This project was funded by a University of Leeds Research Scholarship, and I’d like to thank the Funds for Women Graduates and The Reid Trust for added financial support during a difficult time. I also thank the Highways Agency for permission to access road sites, Graeme Smart for providing monitoring reports, and Tom Cameron for help with statistics. I thank my close friends and family for supporting me, especially my parents for their unconditional love and encouragement in everything I do and for teaching me to believe in myself. Finally, I thank my beloved husband, Reece, for giving up the sunny climes of Australia to support me throughout my studies, for taking an interest in my work despite my lengthy absences every summer and the long hours spent holed up in my study, and for being proud of my every achievement! - iv - Abstract Despite their protected status, little research has been done into the effects of roads on bats or the effectiveness of current mitigation practice. We conducted broadband acoustic surveys on 20 walked transects perpendicular to two major roads in the UK, the M6 in Cumbria, and the M5 in Somerset. Bat activity and habitat variables were recorded at different distances from the road, and the relationship between these variables were investigated using generalised estimated equations (GEE), and ordinal logistic regression. Total bat activity and the activity of Pipistrellus pipistrellus (the most abundant species) were positively correlated with distance from both roads, although the magnitude of the effect was greater by the M6. Distance from the road was positively correlated with the number of bat species by the M6 only. Higher quality habitat surrounding the M5 may have reduced the negative road impacts. The use of direct sampling to collect acoustic data revealed a greater road effect than time expansion methods, which is likely due to increased accuracy through continuous sampling and a larger dataset. Three underpasses and four wire bat gantries were investigated in northern England using echolocation call recordings and observations. The bat gantries were ineffective and used by a very small proportion of bats. Only one underpass located on a pre-construction commuting route could be considered to be effective, and attempts to divert bats were unsuccessful. Further research should focus on crossing structures built on original bat commuting routes, such as underpasses and green bridges. We suggest an integrated approach to mitigation, combining crossing structures and habitat improvements. New crossing structures need to be developed and tested, given the poor success of current structures. Robust pre- and post-construction monitoring using a standardised methodology is essential to assess the effectiveness of mitigation schemes and build an evidence-base for successful conservation. - v - Table of Contents Acknowledgements .................................................................................. iii Abstract ..................................................................................................... iv Table of Contents ....................................................................................... v List of Tables ............................................................................................. ix List of Figures ............................................................................................ x List of Abbreviations ...............................................................................xiii Chapter 1: General Introduction ............................................................. 14 1.1 Scope ........................................................................................... 14 1.2 Bat ecology and conservation ...................................................... 14 1.3 Bats and the law ........................................................................... 15 1.4 The effects of roads on vertebrates .............................................. 15 1.4.1 The barrier effect ............................................................... 18 1.4.2 Collision mortality .............................................................. 20 1.4.3 Habitat fragmentation and edge effects ............................. 21 1.4.4 Noise pollution ................................................................... 22 1.4.5 Light pollution .................................................................... 24 1.4.6 Other effects ...................................................................... 26 1.5 Mitigation ...................................................................................... 26 1.5.1 Underpasses ..................................................................... 27 1.5.2 Overpasses ....................................................................... 27 1.5.3 Linear elements ................................................................. 28 1.5.4 Other possible measures ................................................... 28 1.6 The need for evidence-based conservation .................................. 29 1.7 Purpose of research ..................................................................... 29 1.8 Thesis outline ............................................................................... 30 1.9 References ................................................................................... 32 Chapter 2: The effect of a major road on bat activity and diversity ..... 39 2.1 Abstract ........................................................................................ 39 2.2 Introduction .................................................................................. 40 2.3 Methods ....................................................................................... 42 2.3.1 Survey Design ................................................................... 42 2.3.2 Acoustic analysis ............................................................... 45 - vi - 2.3.3 Statistical analysis ............................................................. 45 2.4 Results ......................................................................................... 48 2.4.1 Overall effects ................................................................... 48 2.4.2 Species-specific effects ..................................................... 52 2.4.3 Effect on the number of species ........................................ 55 2.4.4 Noise effects ..................................................................... 55 2.5 Discussion .................................................................................... 57 2.5.1 The effects of time and habitat .......................................... 57 2.5.2 Road effects ...................................................................... 57 2.5.3 Species effects .................................................................. 60 2.5.4 Conclusions and recommendations ................................... 60 2.6 References ..................................................................................