Reed and Bush Warblers, by Peter Kennerley and David Pearson, illustrated by Brian Small

Published on 28 March 2011 in Book reviews

Christopher Helm, A&C Black, 2010; hbk, 712pp, 42 colour plates, over 350 photographs, colour maps, black-and-white illustrations; ISBN 978-0-7136-6022-7; Subbuteo code M20275; £65.00

This book has been a very long time in preparation; was it worth the wait? Yes, undoubtedly. It is very much in the mould of two other quality Helm publications – Sylvia Warblers and Pipits & Wagtails – although, arguably, its subject matter is more complex than either.

The book covers 112 species, including the Locustella, Bradypterus, Acrocephalus and Cettia warblers. The species order largely follows the findings of the ever-increasing body of research in molecular methods using DNA sequencing, which have led to major restructuring of the Sylviidae. The authors’ decision on exactly which taxa to include is based largely on their desire to cover the most challenging genera. Of most relevance to birders in a Western Palearctic context is that Eastern Hippolais pallida and Western Olivaceous Warblers H. opaca, Booted H. caligata and Sykes’s Warblers H. rama have been moved from Hippolais into a new genus Iduna. It has long been considered that these four species are more closely related to Acrocephalus warblers than the remaining Hippolais.

A series of brief introductory chapters include summaries of migration, moult strategies and ageing. Of particular interest to me was an invited contribution from Staffan Bensch titled ‘Phylogenetic relationships as revealed by molecular analyses’. It provides an informative and useful summary of DNA analyses, their interpretation and their limitations. Another interesting chapter focuses on the origins, distribution, diversity and extinction of Acrocephalus warblers on islands within the Pacific Ocean.

Forty-two colour plates cover all species and, where known, distinctive races. Unfortunately, the reproduction of some of these plates is very disappointing. An accurate assessment of plumage tones is often a crucial step in the identification process, particularly among similar Acrocephalus warblers. The colour tones in the plate illustrating Blyth’s Reed A. dumetorum and Marsh Warblers A. palustris are so dark as to render the species concerned barely recognisable. This is not the only plate to have suffered. I have seen the original plates and the artwork provides excellent representations of the species involved, so the fault clearly lies with the printer and publisher, not the artist. Apparently, the authors were never shown final proofs of the artwork! This amazes me given the monumental scope, and importance, of this work. In accepting these plates the publishers have done a disservice to the authors, artist and prospective readers and I hope that the original scans are included in the electronic version (see below).

The species accounts extend to some 500 pages and follow a set format; they are well written and clearly laid out. Identification covers basic biometrics, structure and plumage/bare parts. A section on ‘Similar species’ provides the reader with an excellent comparison involving likely confusion species and highlights the key features for their separation. Vocalisations are often the best means of species identification, especially for Bradypterus and Cettia, and a section on voice gives phonetic descriptions of elements of songs and calls and, perhaps more importantly, sonograms too. An accompanying CD covering calls and songs would be an excellent addition if a revised edition is produced.

A detailed discussion of moult follows, before sections on habitat, behaviour and breeding habitat. The latter illustrates just how limited our understanding of some species is and by doing so identifies plenty of opportunities for travelling birders to make useful contributions to ornithological knowledge. The distribution section (with maps) covers the breeding and non-breeding ranges of all subspecies where known, while a section on movements covers the timing of migration and, where relevant, comments on vagrancy.

Detailed descriptions are provided of adults, including sexes if they differ, first-winters and juveniles. A section on in-the-hand characters will be of value to ringers, and to birders too, if they can examine high-quality photographs. An in-depth treatment of all known subspecies is given under geographic variation, while an excellent section on taxonomy and systematics gives a fully updated overview of taxonomic changes including, where appropriate, comments on recent molecular studies.

There are photographs of all but eight of the 112 species in the book. Up to 13 appear in some species accounts, often covering a range of races and ages, although more typically 4-7 photographs per species are reproduced. For some species, these are the first photographs I have seen.

Just how good are these species accounts? Although I have seen a reasonable number of Bradypterus and Cettia, my experience of these genera is really too limited to make an informed comment. What I can say is that they appear to be the most complete, authoritative and up-to-date available, and would certainly have helped me to sort some species out more quickly, and possibly more accurately, during my previous travels to Africa and Asia. There is no doubt, however, that the accounts for those genera with which I am more familiar are excellent.

In terms of identification, they include several features that I have not seen published before – for example, the warm panel on the flight feathers of Blyth’s Reed Warbler, which often contrasts with the colder upperparts (and while on the subject of Blyth’s Reed, we should now be checking carefully to ensure that we are not overlooking the recently rediscovered Large-billed Reed Warbler A. orinus).

I particularly enjoyed the in-depth treatment of the subspecies of Pallas’s Grasshopper Warbler L. certhiola; perhaps some autumn vagrants could be identified to subspecies. I also feel better prepared, in the faint hope that the moment might arise, to deal with Britain’s first Gray’s Grasshopper Warbler L. fasciolata. The accounts of Styan’s L. pleskei and Middendorff’s Warblers L. ochotensis go a long way to clarifying that tricky species pair, although recent molecular studies seem to suggest that they are perhaps best considered as conspecific. Another little DNA teaser I noted is the possibility that the western race of Paddyfield Warbler A. agricola is in fact a cryptic species

There are a few things that I would take issue with regarding identification. I disagree that even a poorly marked Lanceolated Warbler L. lanceolata shows a more extensive and better defined gorget than the best-marked Grasshopper Warbler L. naevia. I think primary projections often appear longer in the field than these texts suggest. It is not unusual for Blyth’s Reed Warblers to appear to show a primary projection of two-thirds, neither is it atypical for Sykes’s Warbler to appear show a primary projection of around half the exposed tertials rather than a third. In some cases, such as that of Icterine H. icterina and Melodious Warblers H. polyglotta, assessing the ratio of the primary projection against the distance between the wing-tip and the tail tip is a more reliable assessment of structure than simply using primary projection itself (the ratio is close to 1:1 in Icterine and nearer 1:2 in Melodious).

I think more could have been made of the apparent changes in colour tones in different light and viewing conditions when dealing with vagrant Acrocephalus warblers in a British context. Blyth’s Reed Warblers can be the archetypal chameleon in this sense – they can show almost ghostly, sandy or ‘milky tea’ tones in flight, and then more earthy brown or olive tones when perched moments later. Such perceived changes do, I suspect, account for the apparently pale first-winter Paddyfield Warblers discussed in that species’ account. Perceived supercilium length and the strength of ‘eyebrows’ are also affected by light and viewing conditions.

Among seven useful appendices, one provides datasets of wing-lengths of live birds for selected Palearctic migrants (I was surprised to see that Blyth’s Reed Warblers can apparently show a wing length of up to 69 mm – this would have been worthy of further comment); another comprises a series of useful summary tables comparing characters of similar groups of species; while the last summarises the latest developments since the project finished in 2009. This includes some new discoveries and a summary of recent work on the systematics of Locustellidae and Cettiidae, which yields yet more taxonomic surprises.

I have focused largely on identification in this review but the book is about far more than that. It is an excellent and thorough contribution to our knowledge of some difficult and poorly known species. The authors are to be congratulated in bringing the fruits of theirs and others’ work together in one volume and I am convinced that they will achieve their goal of inspiring people to take forward the various challenges that are apparent from their book. Whether you are a seasoned traveller in Africa or Asia, a rarity hunter around Britain’s coastlines, or more academically minded, this book will contain much of interest to you. The RRP is a hefty £65.00, but I understand that a downloadable electronic version of the book (ISBN 978-1-4081-2751-3) will be available soon and this may be an attractive option to consider.

Paul Harvey

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