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