STAND by for publication later this month of a new book, Vagrancy in Birds.
Based both on their own field studies and extensive research of scientific papers from around the world, co-authors Alexander Lees and James Gilroy have compiled a penetrating and authoritative study on one of the great mysteries of avian behaviour.
How is it that individual birds, usually while on migration, miss their target destination by thousands of miles and end up in completely the 'wrong' place?
Vagrants are, of course, what keep the world spinning for twitchers, but for the birds it is a very different story.
Something has gone seriously awry. Either their internal migration compasses have developed a fault or they have fallen victim to external disrupters such as food scarcity or peculiarities of the weather, notably strong winds.
As well as the theory, the book is packed with instances - supported by numerous excellent photographs - of rare birds in out-of-context locations.
Near the end, there is also a note of concern about twitching.
The authors write: "It is often a very high carbon hobby, especially when it involves long-haul flights, short-haul flights aboard small aircraft or epic long-distance car journeys.
"There is thus a pressing need to reduce the carbon footprint of both amateur and professional ornithology.
"Local patch birding has always attracted stalwarts, but, in an age when emissions need to be reduced, this represents an opportunity to reduce the activity's carbon footprint."
They add: "Species can be 'vagrants' at the local as well as the national or continental level."
Vagrancy in Birds is published on Thursday December 9 by Bloomsbury Helm at £40 in hardbook or £36 as an Ebook.
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