Vagrancy in Birds

Avian vagrancy is a phenomenon that has fascinated natural historians for centuries. From Victorian collectors willing to spend fortunes on a rare specimen, to today’s high-octane bird-chasing ‘twitchers’, the enigma of vagrancy has become a source of obsession for countless birders worldwide.

The ‘twitching’ scene in Britain is well established with reports of large numbers gathering at the site of a rare bird often being reported in the mainstream press. However, this practice isn’t confined to Britain and vagrancy in birds occurs across the globe. For the first time, this book, in no short order, explores the how and the why of bird vagrancy on a global scale, exploring in great detail how birds navigate and the driving forces that find some birds thousands of kilometres from their intended location, and even on different continents from the one they set out for.

My personal favourite chapter, Vagrancy Through Compass Errors, works through the various vagrancy hypotheses and makes for fascinating reading. I really enjoyed reading through the ideas on how reverse migration, mirror-image misorientation, compass errors and the axis of migration might work on a migrant bird and how each of these might explain how ‘lost’ birds end up where they do.

The first 71 pages takes us through all of the possible causes of vagrancy in birds, from compass errors, wind drift and overshooting to extreme weather, irruptions and human-driven vagrancy and sets the scene for the bulk of the book, where the authors look at vagrancy family by family, exploring why some are more prone to vagrancy than others – ever thought why Nearctic herons are so rare here and yet are frequent visitors to the Azores out in the mid-Atlantic? The authors suggest that their southerly breeding distribution in the States may well be why – eight species of Nearctic herons have been found on the Azores, compared to four in Britain.

There are over 300 mouthwatering photographs of rare birds from across the globe illustrating the various sections of the book and these are stunning, making me go back to the book again and again just to look through them. However, this is a book that should be read from cover to cover, to not do so would be to miss out on an awful lot, that said, the way the book is put together does mean that it can be dipped into. I found myself skipping to a family of birds to see which species were most likely to be prone to vagrancy, and when and where they might turn up.

Being able to look at bird families from across the globe and the chances of vagrancy affecting individual birds within them is one of the most interesting things I have read on birds for a long time.

This is a book I will definitely add to my bookshelf.

Book reviewed by Paul Stancliffe