Subject: [Tweeters] white-cheeked geese
Date: Apr 10 14:47:32 2005
From: SGMlod at aol.com - SGMlod at aol.com


Greetings All

I spent much of last weekend (first weekend of April) being a true bird
nerd, and looked at tens-of-thousands of white-cheeked geese in the Willamette
Valley and adjacent Clark Co, Washington.

95+ % of these were minima.

I learned several different things. Firstly, the more I looked, the less
certain I became. Much like looking at gulls.

1) white-neck collars on minima. Complete neck collars in minima are not
rare, at least not when looking at large numbers. I didn't actually count, but I'd
place such birds in the 1-3 percent range. Interestingly, these birds tended
to be birds towards the darker breasted end of minima present (Aleutian's are
typically paler breasted than minima). A couple birds (3-4) had white that
extended well up the anterior neck, almost reaching the cheek patch. There was no
reason to think any of these were Aleutians, as they were the same size and
breast color as the surrounding minima.

2) at this time of year, breast color in minima was highly variable. Purplish
tones were absent. Instead, many had bronzy or coppery colored breasts. In
birds at the paler end of the spectrum, this was merely a rusty wash across the
chest. Such birds were scarce, but still around 1-5 %.

3) lone birds do sometimes present a challenge in separating minima from
taverneri.

4) I saw 1000-1500 taverneri/parvipes. Pale breasted birds all (except one
possible Richardson's) all fell into the long-billed Canada-goose head profile,
thus fitting parvipes. These were about half of the 1000 or so mid-size
white-cheeked geese seen.

5) most of the darker breasted birds had head shapes in between parvipes and
minima, thus fitting my idea of taverneri and fitting B Deuel's article in
Western Birds.

6) We had one very peculiar flock of 100 or so mid-sized birds. These were
90% dark breasted, yet there head profiles fit parvipes. I have little idea of
what to make of these. Bruce Deuel tells me that there is a population of
parvipes that is darker breasted than the rest, but the photos I've seen of such
were not as dark as most of these birds. Maybe that's because they were shot in
sunlight, and we were looking at birds in a steady drizzle. There were a
couple of pale-breasted birds that fit the parvipes profile nicely, and they were
of the same size as these darker birds. Interestingly, among this flock was a
Blue Goose x taverneri/parvipes. Doing some additional research, I looked at
bill length's in Bellrose's Ducks, Geese, and Swans of North America. This shows
that Lesser is closer to Dusky than Taverner's, making me think those
relatively dark-breasted birds were Lessers. Wow.

Also did some research on Blue x white-cheeked geese. In an old article in
the Auk, observers looking for neck-banded geese encountered THIRTY Blue x
Canada (as they were called then) Geese--- they felt the Canada parent was probably
Richardson's Goose, as that's what most of the companion geese were. I had no
idea this cross occurred with such frequency. The Blue Goose breeding range
comes close to, but does not overlap with, Lesser Canada. Since geese pair up
on the wintering range, that may be irrelevant anyway, and it could be a Blue
Goose on the west coast that paired up with a Lesser or Taverner's (I doubt
minima, because the bird would've likely been smaller).

Cheers
Steven Mlodinow
Everett WA