Series: Collection Inventaires & Biodiversité Volume: 8
349 pages, colour photos, colour & b/w illustrations, colour tables, includes DVD-ROM1 customer review
Acoustic Ecology of European Bats is the result of 25 years of research by the author in the field of acoustic detection.
The introduction summarizes the physical basis of biological sonar and gives an overview of the technologies used to convert ultrasound into audible frequencies. The identification criteria for 34 European bat species are given in detail, with an entire chapter devoted to the methodology of the acoustic study of their foraging habitats. Acoustic Ecology of European Bats focuses on the concept of acoustic ecology, illustrated with many examples. This concept explains how the acoustic behaviour of a bat sheds light on its flight environment, its activity, and even its diet, contributing in all cases to improving the reliability of species identification.
A DVD-ROM is included with Acoustic Ecology of European Bats, which comprises over 300 sound sequences (in both heterodyne and ×10 time expansion formats) collected from formally identified individuals flying in natural conditions. It also includes charts in .xls format for the identification of all bat species.
Acoustic Ecology of European Bats contains a wealth of as yet unpublished information indispensable to amateur naturalists and professionals involved in the management of protected areas or in environmental impact studies.
"[...] Acoustic Ecology of European Bats contains a wealth of as yet unpublished information indispensable to amateur naturalists and professionals involved in the management of protected areas or in environmental impact studies. This is the most extensive reference on the acoustic identification of European bats. [...]"
– Stuart Newson, BTO book reviews
Originally published in French
Communication in the Chiroptera reviews the available information about...
First I have to say that this book was a wonderful revelation in the realm of analysing recordings of bat echolocation signals and trying to identify species from their calls (and vice versa). The approach taken here is a signal analytic one, rather than a description by species (as used for example by Russ – also an invaluable reference and for British bat workers an indispensable companion to the current work). Barataud considers the situation of identification using either heterodyne bat detectors, or, more comprehensively, recorded signals from a time expansion bat detector which is also applicable to full bandwidth recordings. He places great weight on audible identification of call characteristics – requiring some comprehensive 'ear training' – accompanied by detailed measurements of call parameters measured from computer generated spectrograms. The latter are used in conjunction with a large number of scatter diagrams, comparing various parameter pairs, in order to distinguish between species with similar calls.
The approach is new to me and appears to be effective and the presentation and layout of the book is clear and easy to follow through the analytic process and I would strongly recommend this book to anyone needing to analyse recordings of bat echolocation calls, whether in some sub-region of the area covered by the book, or in a wider global context. However, I do have some reservations.
I do consider that it is a shame that he bases all his descriptions of how to set up and view spectrograms are based on the use of an expensive commercial program which is possibly beyond the pocket of many amateur naturalists (I certainly can't afford it!). He also bases all his measurements on the appearance of colour contour boundaries, which are artificial and arbitrary boundaries set by the analysis software and which disguise the fact that signals do not have rigid boundaries. I am sure that using the concept of half amplitude boundaries in time and frequency, could provide more objective and reliable parameters, possibly negating the need for subjective aural judgements.
The aural judgements are made by learning from a generous and broad based collection of recordings, supplied on DVD. Many of these are excellent and provide the opportunity to experience the sounds of species that it would be difficult for many readers to observe directly. However, using them for ear training is somewhat flawed by the fact that so may of the recordings are heavily overloaded (and overloading can occur at several places in the recording chain, not just in the digitisation stage – a fact not stressed sufficiently in the book) resulting in the recordings having a large number of artefacts which are not identified as such by the author.
The author does provide some references at the back of the book, but regrettably makes little use of them in the text, even when a reference is strongly called for. For example he always refers to Rhinolophus as using predominantly the fourth harmonic, with a low amplitude second harmonic and completely suppressed fundamental and third harmonics (although he does insist on calling the fundamental a 'first harmonic' – a habit which I was always taught was reprehensible – but we will attribute that deficiency to an error of translation). All other references over the last 55 odd years that I know of consider that Rhinolophus, Hipposideros and the new world cf bats emit strongly in the second harmonic with a suppressed or very quiet fundamental, and this has always appeared to be supported by ontogeny studies. If there is some new, strong evidence for this assumption being wrong then it definitely needs to be cited, and even defended. There are also several other places where I would like to see wider ranger comparisons from the literature – such as in his discussions of two-tone calling where he completely ignores the implications of Pye's observations on Saccopteryx – but I will not attempt to detail them all here.
Overall I would praise the author for his efforts in producing this book and it will form an essential desk-top reference for me when analysing recordings. I will make grateful use of his charts and procedures, while adapting them slightly to my own processes, procedures and software. I would strongly recommend this book to all bat sound analysers, while reserving judgement, or ignoring the parts in which I have less faith.