ddavid

An excellent record & excellent photos.

Just to point out that the IOC, which is the body that the HKBWS Records Committee has decided to follow, separates Bean Goose into two distinct species - Taiga Bean Goose & Tundra Bean Goose.

So potentially you (well, anyone who saw them!!) could be looking at two ticks here...

david

ddavid

Based on the above photos, particularly the pattern and structure of the bills, and the text/plate in Birds of East Asia, it seems to me that we're looking at two Taiga Bean Geese Anser fabalis- presumably subspecies middendorffii  and two Tundra Bean Geese Anser serrirostris - presumably the nominate race.

david

[ Last edited by ddavid at 4/11/2010 15:55 ]

ddavid

Regarding Tony's point about the flank-pattern, the rather plain flanks on one of the Tundra Bean Geese may indicate that it's a juvenile.

I think the difference between these two very similar "species" is well shown in the last of John Holmes's photo above. My understanding is that the bills are the crucial feature. If you look at the photo, the bill of the Tundra Bean Goose on the right has a different shape to the Taiga Bean Goose on the left. There is also a difference in the amount of orange on the bill and how far the orange extends towards the nostrils. Also, the line formed by the closed mandibles is pretty straight on the Taiga Bean Goose but is somewhat downturned on the Tundra Bean Goose, giving a characteristic grin-like expression. The latter feature is clearly visible in other photos and may well be diagnostic.

david

[ Last edited by ddavid at 4/11/2010 17:58 ]