Ibis, Vol.157 Nº1 pp.205-207, 2014 by Anthony Cheke

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DEL HOYO, J. & COLLAR, N.J. Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. 903 pages, numerous colour plates. Barcelona: Lynx Edicions, 2014. Hardback, €185.00, £155.00, ISBN 978-84-96553-94-1. Website: http://www.lynxeds.com.

When single-volume popular world checklists of birds first appeared in the late 1970s, they were just that – simple lists, usually with some basic distribution data and a minimal introduction of two or three pages. At the same time, the great detailed museum-based and fully synonymized world list started by James Peters was still appearing in irregular instalments, running eventually to 16 volumes, including the index. The popular lists were mostly portable quick-reference books, whereas the Peters list was not aimed at individuals but at well-funded reference libraries. Starting with Monroe and Sibley’s taxonomic revolution reflected in their 1993 World Checklist (reviewed in Ibis 136: 509_510), over the last 35 years or so the two concepts have begun to merge, the third edition of ‘Howard & Moore’ (H&M) in 2003 having become a hefty tome adding nomenclatural authorities and extensive taxonomic footnotes, the fourth (2013, reviewed in Ibis 156: 245–246), in an even larger format, has split into two volumes. The book under review, sponsored by Birdlife and the publisher of the Handbook of the Birds of the World (HBW) and larger still, goes one stage further, adding pictures of all species and distribution maps. So far, only the non-passerine volumes of H&M4 and this HBW checklist have appeared.

The later H&Ms and the Illustrated Checklist are more like condensed Peters lists than the cheap and cheerful offerings of the 1970s. They are serious academic reviews, making reasoned (if sometimes contentious) taxonomic decisions. In addition, they seek to create new classificatory sequences based on the expanding information from phylogenetic studies using DNA. Hence, given that ‘Peters’ pre-dates all protein/DNA analysis, these books serve as essential taxonomic updates. H&M4 presents all its decisions in referenced footnotes (although the bibliography is in a CD-Rom), whereas the Illustrated Checklist has in-text explanations with numbered links, in regrettably tiny type, to the printed bibliography. The presentation too is very different – H&M4 has very traditional ‘checklist’ text, whereas the Illustrated Checklist has colour-banded headings, Birdlife status codes, bulleted lists of subspecies and names in French, Spanish and German as well as English. Both books list authorities for all the scientific names, the Illustrated Checklist adding the type localities. Both include extinct species, although their criteria for inclusion differ a little.

At a more fundamental level, the way the Illustrated Checklist differs from H&M4 and other predecessors is in the way the authors have approached species limits. Nigel Collar and one of the ‘assistant authors’ (Lincoln Fishpool) were co-authors on a paper by Tobias et al. (2010, Ibis 152: 724–746) which set out a new method of assessing whether taxa should be considered full species, based on a quantitative scoring of morphological and vocal differences – essentially a more rigorous codification of the Biological Species Concept, with added flexibility. Relationship inferences from DNA studies were deliberately excluded from the decision-making on the grounds that there are (as yet) no constant intertaxon differences that define species. However, despite the claims of greater objectivity, the decision as to how many ‘points’ to give to character divergences remains subjective. This book puts this technique into practice, reassessing the majority of bird taxa using the Tobias scoring system. So does it work on a world scale?

In the original Tobias paper, it appeared that the authors expected their system to put a brake on the rampant splitting that has resulted from the way many recent phylogenetic studies using DNA have been interpreted, and also from the BOU very split-friendly guidelines (Helbig et al. 2002, Ibis 144: 518–525). Tobias et al. calibrated their system using well-studied and widely accepted sympatric sibling species, checked against well-marked European subspecies, and ended up with a score of seven points indicating that two taxa were separate species. In the Checklist, the same scorers (Collar and Fishpool) went through almost all the world’s non-passerines using the same criteria against the species accepted in the full Handbook, and ended up with 462 additional species from split taxa as opposed to only 30 fewer from lumping. About half the 462 had been already proposed by others, the additional ones being largely explained by past over-lumping of Asian and Pacific taxa. I’ve no doubt that some genuine cryptic species have been outed, but at the same time, is the Rainbow Lorikeet Trichoglossus haematodus really seven valid species, or are Collared Doves Streptopelia decaocto in Burma or Spotted Doves Spilopelia chinensis in India truly deserving of elevation? Too many look to me like well-marked races where the intergrade/contact zone is insufficiently well-documented, or taxa on continentalshelf islands that require further investigation. However, there are also a number of northern high latitude breeders where sibling species split, often with little phenotypic change, when forced south by expanding ice in the Pleistocene (e.g. the golden plover pair Pluvialis fulva/ dominica) – there are a lot more of these among the passerines.

A problem for readers of recent checklists (and field guides) is that there is no longer an accepted sequence of orders and families. Despite some admitted collaboration on species limits with the H&M4 editors, the overall sequence in the Illustrated Checklist differs from that list, which in turn differs materially from that in H&M3 (although H&M4 includes a cross-referencing table to its predecessor and to Peters), and that in the original Handbook. Improving understanding of phylogenetic relationships is given as the reason for this flux, but the situation has become so unstable that it is time compilers and taxonomists agreed on a standard sequence that can hold for the foreseeable future, as the Wetmore/ Peters sequence did for 60 years or so – a job for the IOC? There is no scientific reason why a checklist should necessarily reflect every new phylogenetic interpretation, which can always be presented in the book as stand-alone information. Dividing within the family Laridae the two clades of terns either side of gulls, as done in both the Illustrated Checklist and H&M4, seems an over-pedantic pursuit of the perfect list sequence.

Name stability is also an issue that is skirted in these publications. Not only are species often split too freely, so are genera, and there is an urgent need for a Tobias style look at this question. The purpose of a genus is to indicate relationship among a collection of species, but there is no consistency in what degree of distance merits inclusion or exclusion. The Illustrated Checklist, unlike H&M4, rejects the recent splitting of Larus gulls into several genera, but accepts the same for Old-World pied woodpeckers, formerly all Dendrocopos, which H&M4 retained. Rising up the scale, the Illustrated Checklist splits toucans and barbets into five families, treated as one, Rhamphastidae, by H&M4. The many such differences and inconsistencies can only be briefly noted in a review.

And then there are English names. The Illustrated Checklist, in concert with Birdlife, follows a very didactic if simple system that, however, seriously stretches the elasticity of the English language. Two-word (but not three-word) English ‘generics’, like fruit pigeon or scops owl are compulsorily hyphenated, which apart from being both irritating and unnecessary, leads to some total absurdities. ‘Barn-owl’ is hyphenated although only one member of the Tytonidae (Tyto alba) is so titled. Worse, so is ‘Marsh-harrier’, such that the Circus spp. in Madagascar and Reunion become ‘Madagascar Marsh-harrier’ and ‘Reunion Marsh-harrier’ when neither is a marsh harrier (they hunt over forest) – they simply belong to a subclade that is related to Circus aeruginosus (the original Marsh Harrier), and Indian Ocean ornithologists who know the birds, including Birdlife’s own Roger Safford (Birds of Africa VIII), never insert the spurious ‘marsh’ word. Other examples are legion. H&M4 by contrast largely eschews hyphens, and also is willing to accept that ‘English names should be a matter of regional choice with change through convergent evolution, not abrupt dictation’. The Illustrated Checklist does include some alternatives in small print, but the authors clearly believe in a ‘stable definitive set of [English] names for worldwide usage’ – surely that is the function of scientific names? In any case, both English and scientific names require synonymies for certain identification – how many can now identify Black-faced Dioch, Pharoah’s Chicken or the genus Molpastes in modern terms without help from Google (which luckily forgets little. . .)?

This book clearly aims to be the ‘must-have’ checklist for the less austere birdwatcher, hence I feel its downsides need to be highlighted in the hope that future editions may address them. That said, the Illustrated Checklist is a magnificent and beautifully produced book, and a credit to both authors and publisher. The layout is excellent and the illustrations, including usually one for each named subspecies, well chosen – although clearly this isn’t a field guide! It is more than double the price of H&M4, but you do get a lot more, visually at least, for your money.

by Anthony Cheke