Social Calls of the Bats of Britain and Ireland: Expanded and Revised Second Edition

By Neil Middleton, Andrew Froud and Keith French

The social calls of bats are an area about which relatively little is known, with more research still required to expand our understanding. However, these calls are increasingly recognised as a useful aid to identification: they appear to be species specific and are indicative of behaviour – as in territorial activity of males during the mating season. Because the gathering and interpretation of bat echolocation data are a matter of course during research, conservation and consultancy, it is a logical progression to build momentum behind the consideration of social calls in mainstream bat-related work. A better understanding of this subject could mean that non-intrusive survey methods are developed, ensuring that what is being observed is, as far as possible, purely natural behaviour. In turn this will contribute to better interpretation and more suitable mitigation, compensation and/or enhancement solutions.

The book summarises what is understood so far about social calls of the bat species occurring in Britain and Ireland, and north-west Europe. This new edition has been updated and expanded throughout, now containing:

• foreword by the bat authority Michel Barataud, author of Acoustic Ecology of European Bats  
• almost double the number of figures and tables as appeared in the first edition
• completely overhauled call library, all in full spectrum format, with new additional examples 
• three entirely new chapters, covering bat-related acoustics, settings for social interaction, and survey guidelines

The material will be useful to people carrying out bat studies, at whatever level and for whatever purpose, and will also encourage others to undertake further research. What's more, social calls are fascinating to listen to: they are, after all, produced with listeners in mind (other bats). In light of this, the book is accompanied by an extensive downloadable library of sound files which offer a unique gateway into the private life of bats. 

• Language: English
• Publisher: Pelagic Publishing
• Release date: Jul 26, 2022
• ISBN: 9781784273798

Neil Middleton

Neil Middleton is a licensed bat worker and trainer, and is the owner of BatAbility Courses & Tuition (www.batability.co.uk), an organisation that delivers ecology-related skills development to customers throughout the UK and beyond. He has a constant appetite for self-development, as well as seeking to develop those around him, and to this end he has designed and delivered in excess of 400 training events covering a wide range of business and ecology-related subjects. Neil has had a strong interest in the natural world since childhood, particularly in relation to birds and mammals. He has studied bats for over 25 years, with a particular focus on their acoustic behaviour (echolocation and social calls). Other books also available by Neil Middleton: Social Calls of the Bats of Britain & Ireland (2nd Edition). Pelagic Publishing, Exeter, 2022. Is That a Bat? A Guide to Non-Bat Sounds Encountered During Bat Surveys. Pelagic Publishing, Exeter, 2020. The Effective Ecologist – Succeed in the Office Environment. Pelagic Publishing, Exeter, 2016.

Book preview

Social Calls of the Bats of Britain and Ireland

Social Calls of the Bats of Britain and Ireland

expanded and updated second edition

Neil Middleton

Andrew Froud

Keith French

PELAGIC PUBLISHING

First published in 2022 by

Pelagic Publishing

20–22 Wenlock Road

London N1 7GU, UK

www.pelagicpublishing.com

Social Calls of the Bats of Britain and Ireland (second edition)

Copyright © Neil Middleton, Andrew Froud and Keith French 2022

All photographs © the respective photographers as listed

The moral rights of the authors have been asserted in accordance with the Copyright, Designs and Patents Act 1988.

All rights reserved. Apart from short excerpts for use in research or for reviews, no part of this document may be printed or reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, now known or hereafter invented or otherwise without prior permission from the publisher.

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

https://doi.org/10.53061/OELT7442

ISBN 978-1-78427-378-1 Paperback

ISBN 978-1-78427-379-8 ePub

ISBN 978-1-78427-380-4 PDF

Cover images: Bechstein’s bat Myotis bechsteinii © Laura Torrent, naturamontfred.com

Contents

Foreword

Preface

Acknowledgements

About the Authors

Important Notices

1. An Overview of Bats in Britain and Ireland

2. Bat-related Acoustics: An Introduction

3. Settings for Social Interaction

4. Classification of Social Calls

5. Analysis of Social Calls

6. Considerations in Survey Design

7. Survey Guidelines (Bat Social Calls)

8. Species Groups

8.1 Introduction and overview of species profiles

8.2 Rhinolophus species

8.3 Myotis species

8.4 Nyctalus species

8.5 Vespertilio species

8.6 Pipistrellus species

8.7 Eptesicus species

8.8 Plecotus species

8.9 Barbastella species

Appendix: Genus/Species-Specific Considerations

Bibliography

References

Index

Foreword

By Michel Barataud

Bat researcher and author of

Acoustic Ecology of European Bats:

Species Identification and Studies

of Their Habitats and Foraging Behaviour

For more than thirty years, research into the subject of acoustics as applied to bats has grown considerably, allowing numerous inventories and ecological studies to be carried out, with echolocation having received the lion’s share of this knowledge process.

The field of acoustic communication for social purposes is still full of grey areas. However, beyond their complementary role to sonar signals for the purpose of acoustic identification, social calls provide a better understanding of the richness of interactions within this order of mammals, whose social organisation appears to be very elaborate.

There are many circumstances in which social calls are exchanged in the life of a bat: in daytime roosts (between adults, and between mothers and their young); in foraging areas (inter- and intra-specific, with an agonistic or, on the contrary, cooperative aim); within mating territories (autumn swarming locations, advertisement sites, territorial boundaries), and so on.

When one observes the complexity of certain social behaviours within a bat maternity colony (such as grooming or cooperative suckling in Myotis bechsteinii), one can only suspect that the use of acoustics is just as sophisticated. It now seems obvious that the acoustic repertoire of bats is even more diversified in the social domain than in that of echolocation. Moreover, there is a fine line between these two categories. It is becoming increasingly evident that many species use signals with a dual function, without it always being possible to disentangle the relative importance of each. As such, any stone added to the edifice of our knowledge deserves to be saluted.

The first edition of Neil, Andrew and Keith’s book in 2014 was welcomed by bioacoustic chiropterists, as they have very few bibliographic sources in order to compare their field-collected sequences with a reference catalogue. The first edition also deserves to be praised for the thoroughness shown by the authors, and for its synthesis illustrated with modern means (e.g. FFT analyses, downloadable sound files).

This second, revised and expanded, edition continues the momentum, and ensures that this fine team continues a meritorious effort towards improved knowledge. As a user of this book, I have noticed some significant new material. Most parts of the book have been amended with additional information, with the former Chapter 2 now occupying the more richly detailed Chapters 2 and 3, and the addition of the highly relevant Chapter 7 about survey guidelines, associated with Appendix 1 (also downloadable as a PDF). The species accounts are even more detailed (text, spectrograms, sounds), sometimes enriched, for example, by comparisons with rodent sounds to avoid confusion. The book is still presented as a catalogue, but with a general classification of social call types by behaviour and by structure.

The known repertoire of social calls in European bats is constantly expanding and becoming more complex; this diversity of structures makes it very difficult to present them in the form of a dichotomous key, which would facilitate identification work but could also lead to misleading simplifications. An analogical comparison, thanks to the numerous annotated figures and sound sequences, remains a more reliable solution at this incomplete stage of our knowledge.

With time, we will undoubtedly be better able to link each social emission with a more or less precise behaviour, and this will open up further the field of investigation to the ethological domain. The desire to know, as well as we are able, the reasons behind sounds created in the natural world of bats, is not only at the heart of scientific research, but also at the heart of our natural curiosity, which is our constant driving force. Thus, this new book can only be received with interest by ‘bat detectives’.

And finally, if I may, a few personal remarks. The exchanges I have had with Neil show him to have both technical and human qualities, which is never negligible in a world where science tends to be more and more separated from the emotional. As for Andrew and Keith, the link they have with Epping Forest reminds me of a high point for me in rock culture, the Genesis album Selling England by the Pound,* and testifies to their own ‘battle’ to achieve the best!

Michel Barataud

December 2021

(Originally prepared in French; translated by Aileen Hendry)

*Track 5 of this album, entitled ‘The Battle of Epping Forest’

Preface

It’s been a while since the first edition of this book was published (in 2014). To be honest, back then we were unsure how well received it would be. Thankfully, we have been truly humbled by the positive reaction created by the work, and it certainly seems to have helped to put bat social calls at the forefront of people’s minds more often. Did we ever expect, or intend, for there to be a second edition? At the time – definitely not. We didn’t feel overly competent and comfortable doing it the first time around. So, to imagine putting ourselves through the process again would have certainly been in direct conflict with the ‘thank goodness that’s all over’, post-delivery relief we experienced, in advance of the stressful months ahead waiting for that first book to hit the shelves and for us to deal with any reaction.

But, oh, how life has changed. The journey we have been on since then has by all accounts been unanticipated, and a bit of a rollercoaster. Workshops, presentations, training courses and of course not forgetting the two Social Calls of Bats conferences we hosted in 2016 (London) and 2018 (Edinburgh), attended by well over 200 delegates, including many of the ‘great and the good’ in bat bioacoustics. And that takes us to early 2020, when the phone rang. It was Nigel at Pelagic Publishing: Hey guys, are you up for a second edition? The reaction from our team was initially mixed, to say the least, but the carefully considered answer had to be Most definitely, let’s do it.

In agreeing to do this, however, we felt that there was little benefit in merely updating some text and adding a few new calls. We knew we had a great deal more that we could have said in the first edition. So many more examples and thoughts. And of course, adding to this, in the intervening period we never stopped gathering data, helped hugely by countless correspondents sending us recordings.

What’s different in this new edition? There are many new examples within the species descriptions, with most of the calls available from the call library, which is now in Full Spectrum format (previously Time Expansion), making these, broadly speaking, more in line with the software people are using today. We have also included more information about matters such as survey considerations (Chapter 6), as well as specific survey guidelines for social calls (Chapter 7). Furthermore, the academic world continues to produce significant findings, advancing knowledge; thus, the large number of references we had initially could be expanded. Therefore, anyone with the first edition will find lots of new ‘stuff’ the second time around: many of the examples initially used have been replaced, thus widening considerably the material available for reference purposes. So, don’t throw away or ignore your first edition, as that combined with what is produced here gives you a substantial resource.

The social calls of bats continue to be an area about which relatively little is known, with more research required in order to verify what is already thought to be understood, and to explore further our knowledge and understanding of this subject. We are often asked to explain the value of studying bat social calls. In short, they are becoming increasingly recognised as a good aid to identification, as in many respects they appear to be species-specific, as well as being indicative of bat-related behaviour (e.g. territorial behaviour of males during the mating season). In this day and age, when the gathering and interpretation of bat echolocation recordings is used as a matter of course during research, conservation and consultancy work, it seems a logical progression to build momentum within mainstream bat-related work behind the subject of social calls. Indeed, a better understanding of this subject could mean that non-intrusive survey methods may be created or better developed. This would reduce the need for direct disturbance or interference with the study subject, meaning that what is being observed or recorded is, as far as can be, purely natural behaviour. All of this contributing to better interpretation and, consequently, if required, more suitable mitigation, compensation and/or enhancement solutions.

This book summarises much of what is understood so far about the social calls of the bat species that occur in Britain and Ireland, as well as elsewhere in north-west Europe. The material provided will be of benefit to people carrying out bat studies, at whatever level or for whatever purpose, and also encourage others to carry out further research. Social calls are fascinating to listen to: they are after all produced with listeners in mind (other bats). As such, to produce this work without the reader also having the opportunity to become a listener, and therefore fully appreciate the sounds produced, would be falling well short of what could be achieved. This is one of the reasons for including the accompanying downloadable sound files, the other being, that it gives you, the reader, an opportunity to put these recordings through a software package of your choice, thus enabling you to explore any calls of interest in your own way.

The material produced here will not give all the definitive answers relating to the subject. It is a complex area of study, which requires a greater level of understanding. What we are seeking to do is to pull together a lot of the information that currently exists, with the anticipation that, as time progresses, further research will increase knowledge and confidence. So please do not feel that you should read this book with a view to knowing everything there is to know by the end of it. In many respects there are still far more questions than there are answers (not an uncommon concept for those familiar with bats!). For the time being, please regard this piece of work as a source of reference and a collection of material, blended with our own experiences and thoughts, with the aspiration of arousing curiosity and inspiring others to further the understanding of this fascinating subject.

Acknowledgements

The idea for the first edition of this book was born out of the frustration at not having an easily accessible reference against which to evaluate our own findings. The production of the first book gave us a good stepping-stone. With this second edition, we move on, perhaps, to the next step, or at the very least increase the size of the first, giving us a more stable foothold. Our initial feelings of inadequacy have been dispelled by the support we have received on this journey. To everyone who has contributed to, enquired about or promoted what we are doing, we owe a huge debt of thanks. In many instances, material obtained by us or contributed by others has not been included; however, we feel it is important to acknowledge that all the material received has greatly assisted in our overall understanding. There are many more examples that we could have used, and certainly some areas that could be expanded upon (e.g. calls within roosts). There comes a point, however, when the time and space available need to be considered, and work has to go to print. What gets produced in its final format may indeed not be perfect, but let’s not make the perfect, the enemy of the (hopefully) good. And if it is good, then it is only so because of the huge number of contributors, both in respect of the first, and this, the second edition. To that end, we continue to acknowledge everyone here who contributed, in whatever way, to that first edition. Without you, we would not have the material to create this updated work. Additionally, without the contributors who have come along in the intervening period, we would have fallen well short of what has now been produced. As such, we would like to thank and acknowledge the following people and organisations who have all contributed:

A special thanks to Michel Barataud for providing the Foreword and for being such a strong supporter and ambassador for what we are seeking to achieve, and also to Laura Torrent for allowing us to use her excellent photographs, including the front cover. Devon Gilbert for providing support with statistical analysis. Gillian Bourn for her copy editing expertise and suggestions for improvements. Aaron Middleton for providing some valuable artwork, thus supporting various messages we are trying to convey. Sandie Sowler and Sue Swift, who gave up their time to review a near final draft of the first edition, providing valuable feedback which flows through into this edition. Laura Carter-Davis and Aileen Hendry, both of whom have supported the project throughout, and have given valued encouragement and feedback, as well as their thorough proofreading skills. Laura Carter-Davis, Leif Gjerde and Aaron Middleton also, for providing supporting pictures, as well as Laurie Campbell for the use of his picture. Nigel Massen, Moira Reid and David Hawkins of Pelagic Publishing, for their continued support and professional expertise throughout the project, and for still believing in us and the message we are trying to deliver.

Lars Pettersson (Pettersson Elektronik AB, Sweden) for his support in our use of ‘BatSound’ software to generate many of the figures contained within the work, and for facilitating others to provide us with some of the calls we obtained from Scandinavian contributors. The Bat Conservation Trust for promoting our work to the wider bat community, as well as inviting us to deliver numerous workshops and presentations at their events. To the following organisations who assisted and supported the project: Autonomous Province of Bolzano and Eurac Research; The British Trust for Ornithology; Cheddar Gorge & Caves; City of London Corporation (Epping Forest); Code 7 Consulting; Echoes Ecology Ltd; National Trust (Crom Estate and Lodge Park & Sherborne Estate); National Trust for Scotland (Threave Estate, Culzean Castle & Country Park, Hill of Tarvit, Ben Lomond, Brodick Country Park & Goatfell and Falkland Palace & Garden); Natural England; NatureScot (previously Scottish Natural Heritage); Stratton Deanery; Surrey Bat Group; Wildlife Provençale.

In producing some of the extra information contained in this second edition there are a small number of people who really went above and beyond in supporting what we sought to achieve. Accordingly, we would like to say a huge and special thanks to the following: Mike Aston, Brian Briggs, Patty Briggs, Leif Gjerde, Inger Kaergaard, Stuart Newson (BTO), Huma Pearce, Piers Sangen and Marc Van De Sijpe. Each of your contributions has been significant, and anyone benefiting from the contents of this book needs to be aware of that.

This brings us nicely on to a long list of wonderful people who collectively have provided considerable assistance in so many ways, across both editions of the book. To all of you, as follows, who have assisted with the provision of research papers, provided call contributions (whether making the final cut or not), arranged site access, or generally supported and encouraged the project we would especially like to say thank you, it is hugely appreciated: Isobel Abbott, Dave Anderson, Elaine Anderson, Mingaile Anderson (Zebaite), Arnold Andreasson, Christopher Andrews, Henry Andrews, Maggie Andrews, Gail Armstrong, Stephen Atkins, Ross Baker, Peter Banfield, Georg Bangjord, Kate Barlow, Mark Beard, Robert A. Bell, Alex Belle, Kari Bettoney, Adrian Bicker, Kathrin Bögelsack, Lauren Bowers, Scott Brown, Heather Campbell, Fiona Cargill, Max Carstairs, Margaret Clarke, Rob Coles, Martyn Cooke, Chris Corben, Peter Cowling, Sarah Cox, Richard Crompton, Erika Dahlberg, Jessica Dangerfield, Stephen Davison, Ann Deary Francis, Scotty Dee, Pieterjan Dhont, Christian Dietz, Laurent Duvergé, Bengt Edqvist, Tim Elton, Philip Evans, James Faulconbridge, Maurice Febry, Adam Fitchet, Rich Flight, Karl Frafjord, Joanna Furmankiewicz, David (Davy) Galbraith, Adrian George, Mike Glyde, Corinna Goeckeritz, Bill Grayson, Cath Grayson, Lorna Griffiths, Ellie Hack, Julia Hafner, Amy Hall, Andrew Hargreaves, Gareth Harris, John Harrison-Bryant, Rhiannon Hatfield, Les Hatton, Annie Haycock, Søren Hedal, Phillip Heels, Béatrice Herry, Jon Hill, Caroline Hillier, Howard Hillier, Andreas Hilpold, Amelia Hodnett, Colleen Hope, Paul Hope, Morgan Hughes, Dave Hunter, Ashley Ide, Kjell Isaksen, Eric Jansen, Bengt Karlsson, Jackie Kemp, Donald Kernott, Andreas Kiefer, David King, Jeroen van der Kooij, Erik Korsten, Jonathan Langenbusch, Harry J. Lehto, Danielle Linton, Heather Lowther, Steve Lucas, Lindsay Mackinlay, Ulrich Marckmann, Ellen Marshall, Roger Martindale, Andrew Mather, Phil May, Maxine McNaughton, Paul McNie, Tom McOwat, Daniel Menendez, Tore Christian Michaelsen, Aaron Middleton, Audrey Middleton, Kari Miettinen, Cecilia Montauban, Lucy Moorhouse, Colin Morris, Mauro Mucedda, John Muddeman, Stephanie Murphy, Chris Nason, Ian Nixon, Ebbe Nyfors, Samuel Olney, Chiara Paniccia, John Parker, Simon Parker, Claire Parnwell, Steve Parnwell, Jools Partridge, David Patterson, Louis Pearson, Tania Percy-Bell, Liz Petchell, Nick Pinder, Brian Power, Emily Power, Sarah Proctor, John Puckett, Sophie Punteney, John Purvis, Don Simon Rayburn, Benoît Reber, Jo Richmond, Phil Riddett, Graham Roberts, Mike Robinson, Steven Roe, Camille Rostan, Jens Rydell, Harriet Safe, Aileen Salway, Sabine Schramm, Peter Scrimshaw, Laura Shreeve, Heather Simpson (Ream), Greg Slack, Maria Slade, Graeme Smart, Derek Smith (Surrey Bat Group), Stuart Smith, Amy Sneap, Steve Songhurst, Rune Sørås, Laura Spence, Hal Starkie, Cali Tardivel, Carola van den Tempel, Rev. Robert Thewsey, Eva Tilseth, Den Vaughan, Paul Wagstaffe, William Walton, David Watkins, Thea Watson, Elly Weir, Lynn Whitfield, Tina Wiffen, Dan Wildsmith, Clair Williams, Amanda Wilson, James Wilson, Will Woodrow, Nick Woods, David Woolley, Lisa Worledge, Susan Young, Anne Youngman and Maja Zagmajster.

Finally, in 2016 (London) and 2018 (Edinburgh) we hosted ‘Social Calls of Bats’ conferences. The purpose of the events was wide ranging, but in part we wished to acknowledge and show appreciation to many of the people whose work we had referred to during our journey. To this end we feel that it is wholly appropriate that we should fully acknowledge and thank all of the main contributors to these events: Maggie Andrews, Bat Conservation Trust (Lisa Worledge and Liz Ferrell), Ian Davidson-Watts, Echoes Ecology Ltd, Joanna Furmankiewicz, Leif Gjerde, Daniel Hargreaves, David Hill, Ella Lattenkamp, Aaron Middleton, Stephanie Murphy, Luke Rendell, Jon Russ, Sandie Sowler, Carola van den Tempel, Ben Van der Wijden and Susan Young.

During these conferences, funds were raised in honour of the late Kate Barlow, and donated to the Bat Conservation Trust’s ‘Kate Barlow Award’. Kate’s contributions to the world of bats and their conservation were highly significant, including of course her work on social call behaviour. We know she is missed by so many in the bat community, and her presence at these events would have been eagerly sought and greatly welcomed by all concerned.

About the Authors

Picture credit: © Laurie Campbell, 2011

Neil Middleton is a licensed bat worker and trainer, and is the owner of BatAbility Courses & Tuition, an organisation that delivers bat-related skills development to customers throughout the UK and beyond. He has a constant appetite for self-development, as well as seeking to develop those around him, and to this end he has designed and delivered in excess of 250 training events covering a broad range of business and ecology-related subjects. Neil has had a strong interest in the natural world since childhood, particularly in relation to birds and mammals. He has studied bats for over 25 years, with a particular focus on their acoustic behaviour (echolocation and social calls).

Neil first came across his co-authors on a bat course in 2003, and so began a long friendship as they explored many bat-related subjects together, including the material for this book, and of course its first edition.

Other books by Neil Middleton

Is That a Bat? A Guide to Non-Bat Sounds Encountered During Bat Surveys. Pelagic Publishing, Exeter, 2020. ISBN: 978-1-78427-197-8.

The Effective Ecologist: Succeed in the Office Environment. Pelagic Publishing, Exeter, 2016. ISBN: 978-1-78427-083-4.

Email: [e-mail]

Website: www.batability.co.uk

Andrew Froud is an ecologist working in Epping Forest (Essex, England) for the City of London Corporation. He is a licensed bat worker with over 20 years’ experience. The primary focus of his bat-related research has been the study of bats in the ancient semi-natural wood pastures of Epping Forest, examining the impacts of habitat management on the local bat population. Andrew is a keen naturalist and generalist, working on veteran tree management and the restoration and creation of dynamic habitats within an ancient wood pasture ecosystem.

Email: [e-mail]

Keith French has over 20 years’ experience in bat-related work and is a licensed bat worker. He has lived in the countryside throughout his working life and has always had a keen interest in all flora and fauna. Working firstly with cattle and sheep, then as a gamekeeper on a small country estate, gave him daily access to the natural world. It was when he moved to Epping Forest, in 2001, that his interest in bats was born. While attending a bat training course two years later, he met the co-authors of this book. This led to them working together on many bat-related studies, culminating in 2014 with the first edition of this book. He is well travelled, having been fortunate enough to observe and record bats in some exotic locations such as the Amazon, Croatia, Costa Rica, USA and several African countries. Now retired, Keith continues to pursue his interest in bats, as well as being a keen photographer of wildlife, in particular butterflies, dragonflies and other insects.

Email: [e-mail]

All correspondence relating to this publication should in the first instance be sent to Neil Middleton:

Email: [e-mail]

Tel: [phone]

Important Notices

The Sound Library

To accompany the text, we have provided a series of downloadable sound files in .wav format. The files are grouped into folders which tie in with the chapters where they are discussed. To download the Sound Library go to the following link:

http://www.pelagicpublishing.com/pages/social-calls-2e-library

Please note: these sound files vary a great deal in volume.

Throughout, when reference is made to a file in the Sound Library, the symbol  is inserted in the text. Where the symbol is attached to a figure (such as a spectrogram), the figure number doubles as the Sound Library file number. Note that when you open any such sound file, the file itself may be larger than the portion that is shown in the figure. The sound file thus has the potential to show you more on your computer screen than is provided in the text.

Each track has an abbreviation (see table) included in its title, describing the type of recording that you are about to download or listen to.

Social Calls Survey Guidelines

In addition to the Sound Library, please be aware that the following document (pdf) is also available, via the same download link shown above. This in effect gives you a stand-alone, adapted digital version of the material covered in Chapter 7.

Survey Guidelines: Social Calls of Bats (British Isles)

(N. Middleton, A. Froud and K. French, 2022)

CHAPTER 1

An Overview of Bats in Britain and Ireland

Much has been written about the bat species that occur in Britain and Ireland, and it is not the intention here to reproduce what is easily accessible elsewhere. Nonetheless, it is useful to cover a small number of more general topics concerning bats in order that the reader can relate the main subject matter of this book (i.e. social calls) to the species present in the area and their typical seasonal behaviours.

1.1 Species diversity

Within Britain and Ireland there are 17 species of bat regarded as being resident and breeding, represented by two families, comprising eight genera (see Table 1.1). In addition to these, other species have occasionally been found to be present, though these are thought to occur either as migrants or incidentally as vagrants (i.e. population not established and/or breeding not considered to be taking place).

Around the world there are of course many families of bats; however, only two are known to be capable of true hibernation (Ransome, 1990; Altringham, 2003). Not surprisingly, because our temperate climate produces much colder conditions in winter, resulting