Rare Birds, Where and When Vol. 1

Britain has an excellent tally of extreme vagrant bird species, accrued over several centuries. We also have the leisure time to go out in all weathers and the knowledge to record these waifs. Britain probably has a more complete rarity record than any other country in the world. We have more data for analysis, a greater number of vagrant than breeding species, and more obsessive rare bird enthusiasts.

It has been roughly two decades since the accepted records of rare birds seen in Britain and Ireland were compiled as a reference for a popular birding audience. Over that time there have been Rarity Committee reviews, new species added and split (though rarely lumped!), changes in status and distribution, and vagrancy hypotheses expounded.

Now Russell Slack has raised and modernised the game with this new two-volume work, the first of which is now available, dealing with passerines and near-passerines. The book examines the accepted records of all species considered by both the British and Irish Rarities Committees by the end of 2007, as well as all apparently feasible records up until summer this year. The author avoids unilateral decisions, and retains a few possibly contentious records still accepted by the respective committees generally without comment.

Over 220 species accounts are included, along with many subspecies descriptions. These detail range, taxonomy, number of accepted records, a historical review, analyses of where and when the birds were found, and a discussion of occurrence trends and rarity status.

Many selected reports describing additional records are included, often containing less well-known anecdotes and information. An appendix discusses Category D species as well as those Category E birds deemed to potentially occur as genuine vagrants by their presumed likelihood or acceptance as vagrants in other European countries.

One of the many areas in which this book improves on previous similar works is in setting the British and Irish records firmly in a Western Palearctic context, so more accurate global patterns of occurrence and arrival can be inferred. Though rarity records are by definition too few in number, too biased and too patchy for any real statistical rigour, helpful histograms show annual numbers and seasonal timing, including length of stay of most vagrants, and Slack’s interpretations are logical and insightful.

The book covers the well-known ideas explaining vagrancy. An illuminating essay by James Gilroy and Alexander Lees provides a neat summary of their recent papers for those who are less than enamoured with the ‘reverse migration’ and ‘vagrancy shadow’ hypotheses, but the latter are referred to in the text for balance. Short contextual essays by Ian Wallace, Bob McGowan and Adam Rowlands complete the icing on this cake.

Despite the torrent of facts and figures, the book is a surprisingly good read in places, but its real purpose will be as the reference of choice every time a new rarity turns up. Expect monthly use for years to come.

Tech spec

•    Rare Birds, Where and When Vol. 1 sandgrouse to New World orioles by Russell Slack (Rare Birds Books, York, 2009).

•    483 pages, histograms, tables, 45 line drawings, four maps.

•    ISBN 9780956282309. Hbk, £29.99.

Available from Birdwatch Bookshop

First published in Birdwatch 208:46 (October 2009)