Social Calls of the Bats of Britain and Ireland

By Neil Middleton, Andrew Froud, Keith French and Sandie Sowler

Bats are fascinating mammals about which we still have much to learn. As well as using ultrasonic echolocation calls for orientation and while foraging, they also have a complex array of vocalisations for communication. These are known as social calls and are an essential component of their colonial lifestyle.

This book brings together the current state of knowledge of social calls relating to the bat species occurring within Britain and Ireland, with some additional examples from species represented elsewhere in Europe. It includes access to a downloadable library of calls to be used in conjunction with the book.

Downloadable call library 
Social calls are complex and intriguing to listen to; they are after all produced with listeners in mind (other bats). To enjoy and fully appreciate social calls the reader must also have the opportunity to become a listener: each of the presented sonograms in the book is cross-referenced to downloadable ‘time expanded’ .wav sound files which are contained within a much wider library of calls for you to explore.

Included in Social Calls of the Bats of Britain and Ireland 
The authors start with an overview of the species of bats in Britain and Ireland (Chapter 1), and then introduce us to communication within the social world of bats (Chapter 2). Referencing the latest research, the authors explore how these calls can be classified according to their structure, and in many cases the context in which the calls are thought to be emitted (Chapter 3). Chapter 4 addresses aspects of survey methodology to be considered by those studying social calls. This leads on to the analysis of calls (Chapter 5), detailing the specific methods used and parameters commonly measured by researchers.

The final, and main chapter (Chapter 6) introduces the 23 species covered in the book giving each a detailed profile including: habitat preferences, typical roosting locations, roost emergence times, mating strategies and maternity behaviour. Each species profile includes what is known about the social calls for that species and this text is supported by colour sonograms (created using Pettersson BatSound V4.1) of most of the calls discussed. Each sonogram is linked to a .wav sound file (Time Expansion x10) within the downloadable library. The sound files allow the reader to hear, as well as see, the calls produced using any bat sound analysis software that supports the .wav format.

The authors conclude with a bibliography and an extensive list of references directly cross-referenced throughout the book.

• Language: English
• Publisher: Pelagic Publishing
• Release date: Sep 1, 2014
• ISBN: 9781784270001

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

Neil Middleton

Andrew Froud

Keith French

Pelagic Publishing | www.pelagicpublishing.com

Published by Pelagic Publishing

www.pelagicpublishing.com

PO Box 725, Exeter EX1 9QU

Social Calls of the Bats of Britain and Ireland

ISBN 978-1-907807-97-8 (Pbk)

ISBN 978-1-78427-000-1 (ePub)

ISBN 978-1-78427-001-8 (Mobi)

ISBN 978-1-78427-002-5 (PDF)

Copyright © 2014 Neil Middleton, Andrew Froud and Keith French

This book should be quoted as Middleton, N., Froud, A. and French, K. (2014) Social Calls of the Bats of Britain and Ireland. Exeter: Pelagic Publishing.

All rights reserved. No part of this document may be produced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior permission from the publisher. While every effort has been made in the preparation of this book to ensure the accuracy of the information presented, the information contained in this book is sold without warranty, either express or implied. Neither the authors, nor Pelagic Publishing, its agents and distributors will be held liable for any damage or loss caused or alleged to be caused directly or indirectly by this book.

British Library Cataloguing in Publication Data

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

Cover image: Brown long-eared bats in bat box. Photograph by Derek Smith.

Contents

Foreword

Preface

Acknowledgements

About the authors

1.  An Overview of Bats within Britain and Ireland

2.  Introducing Bat Social Calls

3.  Classification of Social Calls

4.  Analysis of Social Calls

5.  Considerations in Survey Design

6.  Species Groups

Rhinolophus

Myotis

Nyctalus

Vespertilio

Pipistrellus

Eptesicus

Plecotus

Barbastella

Appendix: Downloadable Track List

Bibliography

References

Index

Foreword

It is common knowledge that bats live in colonies. In some species these colonies may number several thousand individuals. Animals that live a colonial life do so because the advantages of living together exceed the disadvantages of not doing so. Colonial life provides the advantage of knowledge sharing – where to find food; how to find mates; avoiding danger or warning others of potential harm – all of which are crucial for a species survival. And the means whereby this is undertaken? The answer is of course very much dependent on the species concerned and may involve communication through scent, movement, touch, audible noises or, in the case of bats, sound in the audible and ultrasonic spectrum.

High-pitched ultrasonic sounds are energetically expensive to produce and most bat species emit them when they require a detailed sonic picture of their environment (echolocation). When sound is needed and such detail is not required, the sound produced may be of lower frequencies. Many sounds produced by bats when not commuting or foraging are often lower in frequency than the species’ echolocation calls. It is conjecture that these ‘other sounds’ are all for purposes such as communication, but it is a reasonable assumption given their colonial lifestyle. Such sounds are often grouped together and termed ‘social calls’, although for many their precise purpose is something we can only guess at.

Neil, Andrew and Keith have produced a thoroughly researched book on this little understood and little explored subject, and have made recordings available to us, graphically, electronically and audibly. Their painstaking work of collating existing knowledge, in collecting, categorising and interpreting as many as possible of these non-hunting/non-commuting calls, is an important contribution to our bat survey and impact assessment armoury. Many species groups have vocalisations that are unique to them and an increased understanding of these sounds and their sonograms will improve our ability to identify bat species and interpret their behaviour. As consultants we are continually seeking ways of improving our ability to assess impacts and thus design appropriate mitigation. A better understanding of what bats are doing by surveying the places that they are doing it in, would go a long way to achieving this. Recording of social calls and an improved ability to interpret them could be the key!

In summary this is an important new work which will take our understanding of bats within Britain and Ireland, and therefore the techniques we use to conserve them, to a whole new level. I hope that this work will educate, inspire and encourage further research into this little understood and fascinating subject.

Dr Sandie Sowler MCIEEM

14th March 2014

Preface

Social calls relating to bats is an area about which relatively little is known, with continued research still required in order to verify what is already thought to be understood, and explore further our knowledge and understanding of this subject. During recent years when we have delivered this subject at training events we have been 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 data are used as 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.

This book summarises much of what is understood so far about social calls relating to the bat species occurring within Britain and Ireland. The authors and contributors have collected calls from throughout Europe, and it is anticipated that 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 have been falling well short of what could be achieved. Hence the rationale behind the accompanying downloadable sound files. These are there for you to explore either with or without the use of bat sound-related analysis software.

The material produced here will not give all the definitive answers relating to the subject. It is a complex area of study, which still, relatively speaking, requires a greater level of understanding. What we are seeking to do is pull together a lot of the information that currently exists, with the anticipation that over the next decade or so 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 creating intrigue and inspiring others to further the understanding of this fascinating subject.

Acknowledgements

The idea for this book was born out of the frustration of not having anything that was easily accessible to reference our own findings against. As the number of social calls encountered and the time spent analysing them increased, so did the need to reference what had been found. Talking to people interested in bats and presenting our findings to interested groups prompted a lot of debate as to why we were not delivering such an important subject to a wider audience. Our initial feelings of inadequacy were dispelled by the support and encouragement we have received on the journey, and this work could not have been produced without it. To everyone that has contributed to, enquired about or promoted what we were doing we owe a huge debt of thanks. In many instances material obtained by ourselves or contributed by others has not been included; however we feel it is important to acknowledge that all the material sent to us has been of great assistance to our overall understanding of this subject. There are many more examples that we could have used, and certainly some areas that we could have expanded upon more than we have (e.g. calls within maternity roosts). There comes a point, however, when the time and space available need to be considered, and all of that in conjunction with what the overall objectives of the project at the outset were.

We would like to thank and acknowledge the following people and organisations who have all contributed towards the finished work:

A special thanks to Derek Smith for allowing us to use his excellent photographs, including the front cover, and also to Sandie Sowler for providing the foreword and for being such a strong supporter and ambassador of what we were seeking to achieve. Sandie Sowler also, and Sue Swift, who gave up their time to review a near final draft of the work and provide their valuable feedback which helped to improve upon the final version. Laura 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 Davis also for providing the picture supporting the Pipistrellus species profiles, as well as Laurie Campbell and the National Trust for Scotland Ranger Service for the use of their pictures. Nigel Massen and Thea Watson of Pelagic Publishing, for their continued support and professional expertise throughout the final months leading to publication.

Tania Percy-Bell, Paul McNie, Amelia Hodnett, Andrew Hargreaves, Erika Dahlberg and Will Woodrow for their greatly appreciated support and time during the project. Sophie Punteney for statistical support, as well as assisting with the collection and analysis of calls. Sabine Schramm and Heather Ream for their assistance in the translation of foreign papers.

Lars Pettersson (Pettersson Elektronik, 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 (in particular Lisa Worledge and Anne Youngman) for promoting our work throughout the wider bat community, which resulted in many expressions of interest and contributions of calls. To the following organisations who assisted and supported the project: 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; Scottish Natural Heritage; Stratton Deanery; Wildlife Provencale.

Finally with regards to providing considerable assistance in so many ways, including the provision of research papers, providing call contributions (whether making the final cut or not), arranging site access, and for general support and encouragement to the project we would especially like to thank all of the following: Elaine Anderson; Maggie Andrews; Kate Barlow; Mark Beard; Kathrin Bogelsack; Heather Campbell; Peter Cowling; Sarah Cox; Richard Crompton; Pieterjan Dhont; James Faulconbridge; Maurice Febry; Adam Fitchet; Joanna Furmankiewicz; Mike Glyde; Corinna Goeckeritz; Rhiannon Hatfield; Les Hatton; Soeren Hedal; Phillip Heels; Jon Hill; Colleen Hope; Paul Hope; Dave Hunter; Kjell Isaksen; Jackie Kemp; Jeroen van der Kooij; Danielle Linton; Heather Lowther; Lindsay Mackinlay; Roger Martindale; Phil May; Tore Christian Michaelsen; Aaron Middleton; Audrey Middleton; Stephanie Murphy; Ebbe Nyfors; Claire Parnwell; Steve Parnwell; Jools Partridge; David Patterson; Phil Riddett; Mike Robinson; Steven Roe; Jens Rydell; Harriet Safe; Amy Sneap; Rev. Robert Thewsey; Paul Wagstaffe; Nick Woods; David Woolley and Maja Zagmajster.

About the Authors

Neil Middleton is a licensed bat worker and trainer, with 20 years’ experience, having carried out most of his bat-related work within the UK and Europe (Ireland, Cyprus, France, Spain and Hungary). He is the managing director of Echoes Ecology Ltd (www.echoesecology.co.uk), an ecological consultancy he established in Scotland during 2006. Neil has been involved with many bat-related projects to date, including the Bats & The Millennium Link (BaTML) project, which was set up to study the use of canal corridors by bats in Scotland (www.batml.org.uk). Neil is an accomplished trainer across a wide range of bat-related subjects, having developed and delivered well over 100 events to date. Neil first came across his co-authors Andrew and Keith when they all attended a bat course in Somerset during 2004, an event that not only inspired all three of them, but also was the beginning of a long friendship as they explored many bat-related subjects together, including the material for this book.

Email: [e-mail]

Picture credit: ©Laurie Campbell, 2011

Andrew Froud is an ecologist working for the City of London Corporation, within Epping Forest (Essex). He is a licensed bat worker with over 10 years’ experience. In 2006, together with Keith French, he set up a six-year research project, within a small part of Epping Forest, to examine habitat use by bats in conjunction with the impact of habitat changes brought on by the sites’ Conservation Management Plan. Andrew’s initial interest in social calls came about when he and Keith discovered the first known Nathusius’ pipistrelle advertisement roosts for Essex on their site. Since then, he has been fascinated by the subject, and recorded many social calls across a wide range of species. In recent years Andrew has delivered presentations on this subject to course delegates, local bat groups and natural history groups.

Email: [e-mail]

Keith French has over 10 years’ experience with bat-related work, and is a licensed bat worker, both living and working within Epping Forest (Essex), where he is employed by the City of London Corporation as the ‘Head Forest Keeper’. Having a driven associate like Andrew has helped fuel his enthusiasm to delve deeper into this complex and relatively unresearched subject. After recording their first Nathusius’ pipistrelle in an ancient oak pollard, the search was on to record social calls from other species, especially noctule and Myotis. Keith has also been keen to pass on the knowledge he has gained by giving guided walks, presentations and allowing volunteers the chance to improve their skills. He is well travelled, having been fortunate enough to observe and record bats in some exotic locations