February 2013 – vol. 106, issue 2, pp 109–113 By J. Martin Collinson, Thomas Shannon, Paul Archer, Nigel Odin, Roger Riddington and Paul WalshAbstract The criteria for robust identification of migrant Siberian Chiffchaffs Phylloscopus collybita tristis in western Europe continue to prove controversial. Whereas many 'classic' birds are identifiable on the basis of plumage and vocalisations, many others are less straightforward. This article desc... This article is only available to registered users.To read more, please log in or purchase a subscription.