Friday, 19 February 2010
MIDDENDORFF'S-TYPE BEAN GEESE on Shetland
On Saturday 13 February, Juan Brown obtained an excellent selection of shots of a party of 7 'Bean Geese' that were present at Sandwick, in South Shetland - see http://www.nature-shetland.co.uk/naturelatest/latestbirds.htm
At least two of the flock showed characteristics commonly associated with MIDDENDORFF'S BEAN GOOSE (Anser fabalis middendorfi), being proportionately larger and heavier, with a much longer, deeper-based bill and a longer neck, and restricted orange. New research into the Bean Geese has found in isotope analysis that middendorfi is actually the most divergent clade of the group and probably best treated as a separate species.
With much of Scandinavia and Western Russia still covered in up to three feet of hard, lying snow and ice, recent migrational movements by many hundreds of wintering TAIGA BEAN GEESE in the south has been disrupted and consequently many have been forced further west to Britain, hence these flocks on Shetland and others in East and North Yorkshire.
This Shetland flock of 7 certainly contains TAIGA BEAN GEESE-types and I suspect that all 7 are of just one species. Perhaps the variation of Taiga Bean Geese is still poorly understood.
MIDDENDORFF'S BEAN GOOSE breeds in the taiga of eastern Siberia, mainly east and north of Lake Baikal, from the Khatanga to the Kolyma regions, and extending to the Pacific coast of Russia as well as to the Altai and northern Mongolia. These birds winter primarily in eastern China and Japan, as well as in South Korea. The population of this form is in steep decline, with perhaps no more than 10,000 birds surviving (Lee Evans).