Purposes, Procedures, and Plans in Updating the Clements Checklist 6th Edition

John W. Fitzpatrick
Director, Cornell Lab of Ornithology
October 8, 2007

The purpose of the Clements Checklist is to make it as easy as possible for anyone--non-specialists and professionals alike--to keep track of the ever-changing “master list” of birds of the world. We have two goals in providing regular updates to the Clements Checklist (1) to correct errors in the printed version of the 6th Edition, and (2) to update the taxonomy based on published technical research in peer-reviewed literature and vetted in the avian systematics community.

Professional ornithologists at the Cornell Lab of Ornithology will correct and update the Clements Checklist 6th Edition on an ongoing basis. We are finding many errors on our own, and we also appreciate the efforts of the user community in locating many others and communicating these to us. For the most part, the update posted on October 8, 2007 concentrates on correcting the errors. We also are busy reviewing recent technical publications in avian taxonomy, and future updates will include a number of taxonomic changes proposed over the last several years and that have been accepted by respected authorities in the field. Our long range intent with such updates is to reflect consensus of the experts.

Whose taxonomy do we follow?

Uniting the taxonomic treatments and philosophies from different regional authorities into a single, cohesive list is no small task. Inevitably, conflicts exist both on specific issues and in general approaches to species limits, English names, species sequences, and other matters. For the Western Hemisphere, our first authority remains the American Ornithologists’ Union (AOU). The long-standing AOU Committee on Classification and Nomenclature treats all bird species occurring from Panama and the Caribbean northward, publishes the official Checklist of North American Birds (AOU 1997), and publishes annual Supplements to this Checklist each July in The Auk. Thus, for species of North America, Middle America, and the Caribbean, our standard procedure will be to follow the AOU nomenclature to the letter.

Even this rule, however, has its exceptions. Clements differs from current AOU treatment in a few cases involving species or species complexes with natural ranges largely or entirely outside the AOU area. For example, European authorities assign different names for European Herring Gull, Vega Gull, and American Herring Gull (see Crochet et. al. 2002 and Liebers et. al 2004). Although such changes are not yet adopted by the AOU, we expect them to be shortly, and in these rare instances the Clements list occasionally will be ahead of the AOU.

For South American birds, our intention in future updates is to modify the Clements list to follow the taxonomy and nomenclature of the AOU’s South American Classification Committee (SACC). The SACC presents a scholarly treatment of all species occurring south of Panama, and they post their findings (plus literature citations and explanations) on the SACC website. Effort is currently underway within the respective AOU committees to reconcile a number of differences between the SACC list and the North American list. As these reconciliations occur, we will update the Clements list accordingly. Eventually, therefore, the Clements Checklist will represent faithfully the comprehensive list of Western Hemisphere birds as accepted by the two AOU committees.

For birds of the Old World and the oceans, we shall adhere as closely as possible to the taxonomy and nomenclature published by regionally recognized scientific bodies (e.g., British Ornithological Union for European birds) and/or technical experts (e.g., Paul Scofield for New Zealand Birds). Where conflicts exist, we will tend to follow the treatment of the Handbook of Birds of the World series (Lynx Ediciones, Barcelona, Spain), as these relatively recent accounts were prepared by recognized experts on the respective taxa.

Sequence of species and subspecies

Ornithology has entered an extraordinary period of discovery in systematics and taxonomy. Revelations from genetic studies are shifting some of our most familiar bird species into different families and even orders. (One need only study the recent peregrinations of the New World Vultures, Carthartidae, within the AOU taxonomy to get an idea of what lies ahead.) As a result, the sequence of families, genera, and species will be extremely fluid for many years to come. For the time being we will follow the AOU’s treatments within genera (e.g., recent shift of species sequences in the expanded genus Spizaetus), but will tend to remain conservative in changing sequences within the Clements Checklist on the theory that no specific sequence is likely to be “the correct one” for some time to come.

Updates to ranges and status

We are finding and receiving numerous cases in which the ranges of species or subspecies as published in the Clements Checklist 6th Edition are incomplete, or include misspellings or obsolete place names. For the present, we will post range updates only in cases of outright and egregious error. However, we are continuing to accumulate and check all suggested changes in range, and will present these comprehensively in a future post, probably in database format.

The Clements Checklist does not include distributional records for vagrants, even those that occur annually (e.g., Pectoral Sandpiper in Europe, Eurasian Wigeon in North America). This means that new North American records of extralimital species (e.g., those published in the 2007 Supplement to the Checklist of North American Birds) are not mentioned in the posted updates.

Frequency of updates and downloadable spreadsheet

Official updates and corrections to the Clements list will be posted once a year in October. Each new post will be dated separately, and will include only the latest changes. Links to previous posts will remain active, so that the Clements Checklist web site will continue to provide the comprehensive list of changes. It is our intention to post a fully updated, downloadable spreadsheet of the Clements Checklist database, referenced to page numbers in the printed 6th edition, by fall 2008.

Input welcome, and thank you!

As always, we welcome and encourage users of the Clements Checklist to contact us (cornellbirds@cornell.edu subject line “Clements Checklist”) with any errors or possible errors you encounter. We will do our best to answer your emails directly, although there may be some delay before we do so. We appreciate those we have received already, as well as all the feedback we are receiving from the user community. We are committed to doing our very best to correct this checklist and to keep it active, up to date, and user-friendly.

We thank all those who have provided input to date. For assistance with this October 2007 posting, we thank the following individuals: Chuck Almdale, Barry Attridge, Jerry Blinn, Ned Brinkley, Peter Coburn, Bill Collins, Andrew Duff, Robert Eisberg, Wim Heylen, Ron Hoff, Marshall Iliff, Erling Jirle, Paul Johnson, Theo de Kok, Jim Kopitzke, Niels Larsen, Jo Ann MacKenzie, Glenn Mahler, Larry Peebles, Brian Penney, Shaun Peters, Daniel Philippe, Colin Richardson, Kjell Scharning, Brian Sullivan, Phil Tizzard, Iain Tomlinson, Chris Wood.