Subject: White-crowned Sparrow puzzler
Date: Jun 7 11:52:21 1996
From: "M. Smith" - whimbrel at u.washington.edu


Hi Tweeters, here's a puzzle I hope you can help solve. I'd appreciate
any help available. First, the background:

Three distinct subspecies of White-crowned Sparrow are known to breed in
Washington. Z.l. pugetensis, the widespread bird of western Washington,
Z.l. gambelii of subalpine/alpine habitats in western Okanogan Co., and
apparently locally south to Naches Pass (did I get that right Gene?), and
Z.l. oriantha which is known to breed at Mt. Salmo in Pend Oreille County.
No Breeding Bird Atlas data indicate that White-crowned Sparrows breed in
the Blue Mts. Larrison (in Weber and Larrison 1977) stated that Z.l.
oriantha breed in the Blue Mts. Subsequent conversations with folks
(especially Russell Rogers) indicate that there is very little evidence
available to support that claim. Dennis Paulson has noted that he heard
singing birds up there once, which is the only real evidence that I had
been able to uncover.

Until today that is, when I got the following data from the Conner museum
on two specimens taken in late June 1977. The museum label data is listed
here:

#77-548 .3 mi E, .1 mi N of Mt. Misery, 6200', Garfield Co., WA
25 June 1977 D.P. Mack 143 (Coll. R.E. Johnson)
M, testes L11x8, R12x8, no bursa, sl. fat, no molt, skull os., 25.6 g.

#77-630 .3 mi E, .1 mi N of Mt. Misery, 6200', Garfield Co., WA
25 June 1977 D.P. Mack 163 (Coll. R.E. Johnson)
M, testes L11x7, R12x7, no bursa, sl. fat, no molt, iris brown, skull os.,
25.4 g.


So the puzzle is this. With the information given above, is it possible
to tell whether or not those birds were in breeding condtion at the time
they were collected. I assume the tell-tale measurement would be testes
size, but I know very little about this. Is that size indicative of
breeding? Are there confounding factors which don't make the solution
that easy? I didn't get subspecies from the museum, but have put in a
request for that info if they have it.

There is also the likelihood (Dennis mentioned this) that White-Crowned
Sparrows breed irruptively in the Blue Mts. in response to climatic and
habitat changes throughout their range. So it could be that in the late
70's Larrison wasn't going out on a limb, but now the sparrows are not to
be found in that region.

A thorough discussion amongst tweeters about this would make me very
pleased, and might hash out some answers. At the very least, this data
gives me somewhere else to check when I head out there next week.