Mike and Everybody,
The primaries and rectricies on all the birds I saw in this group were
rich dark black! So, these were all fully mature males. Hum? What could
be limiting the intensity and the extent-of-coverage of red on the heads
of these male tanagers? Some dietary deficiency or maybe some metabolic
toxin that they picked up on their wintering grounds? I know that the
males do have more yellowish on the head in winter, but it is now mid-late
May. Would you expect the majority of the males to be in full breeding
colors by this time? None of the males in this group were in full
alternative plumage yet.
Tiz a puzzlement, me2
****************************************
Maureen Ellis, PhD, Research Scientist
Toxicology Group at Roos 1, 284A
Lab/Office phone: 206-685-1938
Dept of Environmental Health, Mailstop 354695
School of Public Health and Community Medicine
University of Washington, Seattle, WA 98195

E-Mail: me2 at u.washington.edu
****************************************
"Why are we now traveling into space? Why, indeed, did we trouble to look
past the next mountain? Our prime obligation to ourselves is to make the
unknown known. We are on a journey to keep an appointment with whatever
we are."_____Gene Roddenberry

On Mon, 20 May 2002, M. Donahue wrote:

> Maureen and Tweeters,
>
> I studied a large series of western tanager specimens, in order to
> characterize and describe their molt cycle. (The results of this project
> will be published in The Auk later this year, in a paper coauthored with Luke
> Butler and Sievert Rohwer.) I wasn't specifically collecting data on the
> extent of red on the head, but anecdotally, the one year old males did not
> have less red on the head than older males. I was surprised at this finding,
> as it was not what I would have predicted.
>
> The best way to age male western tanagers in the spring is by the color of
> their flight feathers (the primaries and rectrices). One year old males
> still have the flight feathers that they grew as juveniles, which by this
> time of year are a faded olive green (which appears brownish). The older
> males, those at least two years old, have black primaries and rectrices.
> This difference is actually fairly easy to observe if you get a half way
> decent look.
>
> >From the distribution of age classes in the spring--dates and
> localities--it appears that the one year old males do indeed migrate later
> in the spring than the older males.
>
> Mike Donahue
> Seattle
>
>
>
>
>