Subject: Re: White-crowned Sparrow Puzzler
Date: Jun 08 02:39:08 1996
From: "Jack Bowling" - jcbowling at mindlink.bc.ca


Michael Smith wrote:

<snip>

>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.
88 and 77 cubic mm
<snip>

I am staring a page of "The Spring Migration of Gambel's Sparrows through
Watson lake, Southern Yukon Territory" by Barbara B. Dewolfe, George C.
West, and Leonard J. Peyton as published in The Condor 75:43-59, 1973.
In the section "Testis Volume and Histologic Stage", the authors state that
the testis volume of 25 dissected males ranged from 16.9 to 137.1 cubic mm.
"Fifteen males collected between 2 and 8 May averaged 60.19 cubic mm, and
all of these birds were in the "fat" category. Ten males collected between 9
and 15 May averaged 86.11 cubic mm. Eight of these last ten birds were
"thin"." Only the length and width were given in the measurements of the two
specimens in question. Perhaps someone would know the average depth of WCSP
testis and thus enable volume estimation? But even if it were only 1mm, then
both birds would fall into the middle of the measured ranges. Of course, if
they were _Z. l. oriantha_, then the testis volume would likely be shifted
higher since it is a bigger race.

The authors also found that all males contained only the two most advanced
stages of spermatid development: "Stage 6, in which spermatids but no mature
sperm are present; and Stage 7, breeding condition, in which mature sperm
are present in the lumens of the semeniferous tubules." I doubt that a
dissection of the two birds would reveal anything re. sperm development 19
years after death.

I don't know if this helps at all. I recommend trying to find this edition
of The Condor. The rest of the WCSP article is quite interesting, also.

- Jack


***************************
*Jack Bowling *
*Prince George, BC *
*jcbowling at mindlink.bc.ca *
***************************