Subject: [Tweeters] goose correction
Date: Mar 11 15:07:34 2006
From: Dennis Paulson - dennispaulson at comcast.net


Hello, all.

I mentioned the flock of Cackling Geese we saw at Montlake Fill on
3/10, and I called them "minima." This is the very dark subspecies
that breeds on the Yukon/Kuskokwim delta and winters largely in sw.
WA and w. OR, as well as farther south into CA. Steve Mlodinow, local
expert on white-cheeked geese, called to my attention that they were
probably subspecies taverneri, a subspecies that breeds in western
and northern Alaska and winters widely in the West. Both are common
in western Washington, either in pure flocks or sometimes mixed.
Usually they remain in family groups even when mixed, and they can
often be detected in that way (groups of paler and darker birds in a
larger flock).

There is still much discussion on how to distinguish various
subspecies of Cackling and Canada Geese, as some of them overlap in
migration or winter, and any of them might move outside its normal
range and thus be an interesting vagrant. There is equal discussion
on how to distinguish the Cackling Goose Branta hutchinsii taverneri
from the Canada Goose Branta canadensis parvipes, two extremely
similar birds even though their mitochondrial DNA seems to indicate
they are different species. So not all Cackling Geese are easy to
distinguish from all Canada Geese! David Sibley has a good discussion
of the problems on his web site at http://www.sibleyguides.com/
canada_cackling.htm.

So even though a lot of the white-cheeked geese we see are the
resident prolific pesty poopers Branta canadensis moffitti, it's
always worth looking a bit closer at them.

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382

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