Changes to the British List (13 March 2019)
The British Ornithologists’ Union Records Committee (BOURC) has added the following subspecies to the British List:
Cackling Goose Branta hutchinsii hutchinsii (Richardson’s Cackling Goose)
Third-calendar-year or older, Holkham Freshmarsh, Norfolk, 6-23 February 1999 (photographed).
After many years of debate some clarity about the taxonomic relationships, identification and distribution of the North American ‘white-cheeked’ geese of the genus Branta has been achieved (North American Birds 62, 344-360, British Birds 109: 677-684). This allowed the acceptance of Cackling Goose Branta hutchinsii to the British List (Ibis 159, 238–242). However, at that time, it was felt that the first British record, from Plex Moss and Formby Moss, Lancashire during November 1976, could not be conclusively identified to subspecies.
Following this decision, a number of candidates were considered by BOURC for subspecies-level acceptance, resulting in a unanimous decision that the Holkham Freshmarsh individual from November 1999 showed features consistent with the subspecies B. h. hutchinsii. Furthermore, there was no evidence of a captive origin, with the bird seen in a flock of Pink-footed Geese Anser brachyrhynchus, a plausible carrier species for a vagrant crossing the Atlantic. Thus the record and subspecies was accepted to Category A.
Richardson’s Cackling Goose breeds in north and central Canada and Greenland, migrating to winter in Texas, USA and Mexico.
Further details will be published as part of the BOURC’s 50th report due to be published in Ibis in January 2020.
Upon publication of this change, the British List stands at 619 species (Category A = 601; Category B = 8; Category C = 10).
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