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Monday, 22 February 2010

Shetland TAIGA BEAN GEESE

Mariko Parslow, who spent many years studying Bean Geese in the Yare Valley and at staging posts along their return route in spring, kindly commented on the possible Middendorffi on Shetland I flagged up a few weeks ago. This is what she said...

Dear Lee

I saw your recent posting hinting that the Shetland Bean Geese might have been Anser fabalis subsp. middendorffii, which I used to study closely in 1980s. In this subspecies, (or may it be a species) the ratio between upper bill length: skull length is 1.15 ~ 1.30: 1.0, whereas in Anser fabalis subsp. fabalis it is 0.95~1.05: 1.0. (say about same length). The bill depth at the base of the bill is about a half of upper bill length in subsp. middendorffii, whereas less than that in subsp. fabalis. This has been published in Japanese Journal of Applied Biology in ca. 1983.

Among the photograph on your web page and those in the Shetland link, none shows such an individual which fits in this criteria of subsp. middendorffii. The photo on your website shows a family of subsp. fabalis, i.e. probable parents plus semi-adults nearly a year old, and other photos in Shetland links show various semi-adults of all subsp. fabalis.

Shetland is not very much out of way, when the Scottish wintering population of subsp. fabalis migrates back to its breeding range in South Sweden.

Yours, Mariko Parslow