British Birds December 2011
The December issue of British Birds is now out.
Amur Falcon in Yorkshire: new to Britain
A small falcon, initially thought to be a first-summer male Red-footed Falcon was discovered on 14th September 2008 at Tophill Low nature reserve, in Yorkshire. The bird was in moult during its stay and photographs of it in flight on 15th October revealed white axillaries and some white underwing-coverts, which had not been present when it arrived. These features enabled the bird to be reidentified as an Amur Falcon. The bird was accepted as the first British record of Amur Falcon and added to Category A of the British List. The identification of second-calendar-year Amur Falcon is reviewed, other European records are summarised, and the species’ migration, breeding and wintering ranges are discussed.
From the Rarities Committee’s files: Identification of Caspian Gull
Part 2: phenotypic variability and the field characteristics of hybrids
Variability in large gulls creates problems for field observers, not least because of the possibility that hybridisation might be responsible for the appearance of what are perceived to be atypical individuals. However, without detailed information on the phenotypic variability in birds of known provenance, it is difficult to resolve debates about the identification of such atypical birds. This paper, by Chris Gibbins, Grzegorz Neubauer and Brian J. Small, is the first attempt to develop a quantitative system to address this problem. The authors use numerical scores from a sample of 404 birds (including pure and hybrid individuals) to describe objectively patterns of variability in the structural and plumage traits traditionally used to identify Caspian Gulls. Application of the scoring system requires careful observation and good-quality photographs, so it may not always be possible to score candidate birds, but incompletely documented birds can be still be assessed by observers and records committees.
A double century for Bitterns
The year 2011 has been a double-century year for the Eurasian Bittern: not only did the number of booming males in England top 100, but it is exactly 100 years since the species was rediscovered breeding after a long absence from the country.
BTO research update
Mike Tomas and collegues present an update on the disease trichomonosis, with evidence that migrant Chaffinches from Britain may have casued the spread of the disease to Fennoscandia. Jacquie Clark gives an update from the Ringing Unit, summarising the wealth of information now available on the BTO website.
Topics this month include the surveys of the St Kilda Wren.
Reviews, News & comment and Recent reports complete the December issue.
For more details, and to see a recent issue of the magazine, visit our website at www.britishbirds.co.uk