A definitive list? by Dominic Mitchell, Birdwatch, October 2014

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A definitive list?

WHY a new checklist? In a world with several major tomes already cataloguing every bird species and subspecies, this pertinent question is the starting point for Lynx's latest contribution to the canon of ornithological literature. Co-authored by Josep del Hoyo, founder of the Spanish publisher, and Dr Nigel Collar of BirdLife International, this authoritative checklist (hereafter ICBW) aims to get off on the right foot by setting out precisely why it's not just different to its predecessors, but why it also represents progress.
    
Key to this are its underlying taxonomic principles. The authors have adopted a standardised approach to determining exactly what constitutes a species by applying the criteria of a single - albeit landmark - paper (Tobias et al 2010) which uses a scoring system to rank differences between taxa. This process assesses a range of factors - plumage, morphometrics, vocal characters, distributional information (for example interbreeding) and genetic evidence - to arrive objectively at a conclusion, rather than simply accepting the findings of published papers or the views of other checklist authors by default.

There are clear advantages to such a consistent and standardised approach, though the authors reveal in the introduction that adoption of these principles elsewhere in the four years since they were published has been slow. Perhaps this is partly because their application sometimes conflicts with now-accepted interpretations of genetic and other studies which have resulted in 'splits', and the description of new species through such peer-reviewed work is understandably taken to represent progress.
    
There are indeed 'lumps' here, but it's not just one-way traffic. While BirdLife might traditionally have been regarded as taxonomically conservative, the process of applying the Tobias criteria to non-passerine orders has resulted in some significant changes in both directions. There are far too many to list in detail here, but by way of a few examples from a Western Palearctic perspective, splits adopted include Siberian (aka Stejneger's) and White-winged Scoters, Cape Verde and Desertas Petrels, Scopoli's and Cory's Shearwaters, Monteiro's and Madeiran Storm-petrels, and Northern and Hen Harriers. On the debit side, Bean Goose (including Taiga and Tundra), Common Teal (Eurasian and Green-winged), Green-backed Heron (Green and Striated), Whimbrel (Eurasian and Hudsonian) and Sandwich Tern (including Cabot's) are among the 'lumps'. It will be interesting to see what influence, if any, such changes will have on the view of authorities such as the British Ornithologists' Union's Records Committee and its British list, and the increasingly popular (and taxonomically more 'progressive') IOC world list maintained by the International Ornithologists' Union.
    
Anyone flicking through this volume will also be struck by the new sequence of families. This makes navigation difficult at first, and it will take time to get used to a running order in which pigeons follow soon after tropicbirds, hummingbirds precede rails and cranes, and diurnal raptors follow owls. But in terms of layout, ICBW is a joy to browse. Unlike other global checklists, it illustrates every species. A fair few subspecies are illustrated in whole or part figures too, with plates facing relevant text on each spread, and also including distribution maps. While the bulk of the artwork originates from Lynx's 17-volume series Handbook of the Birds of the World (HBW), there are many new illustrations and many more which have been reworked and improved. No other checklist of world birds is comprehensively illustrated in this way.

The effect of this is to give the book the feel of a single-volume condensed version of HBW. There is far more to it than that, however. The 54-page preamble to the main systematic section s itself an illuminating window on the world of speciation, systematics and nomenclature, and on the problems of compiling and maintaining a definitive list. It's essential reading for any serious birder, if by necessity a little heavy going at times. At the tail end of the book, a reference maps section is essentially a built- in world atlas, while references easily exceed 2,000 in total.

As an overall package, this checklist cannot be recommended highly enough. Its raison d'être can't be faulted, even if the knowledgeable reader may raise an eyebrow at particular taxonomic outcomes. As a single reference to non-passerines it is way ahead of the field, and the passerine volume is now keenly awaited. It's expensive, but consider it an essential investment.
    
Dominic Mitchell