Dennis wrote:

>Actually, I don't think that's the case. We have birds in the collection
>that are fully red but are quite young (conspicuous bursa and partially
>pneumatized skull), and I think male House Finches typically acquire their
>red plumage by their first winter. We have other specimens that are
>yellow-orange but apparently mature (worn summer birds, although specimens
>collected many years ago so no age data). Furthermore, I never see
>yellow-orange birds at my feeder, but there are lots of juvenile House
>Finches each fall (like right now). Finally, there are populations in
>California and Hawaii that consist almost entirely of yellow-orange birds.

>I think the lack of red represents a dietary constraint, and the literature
>on House Finches would bear this out.

In addition to what Dennis has pointed out, it appears that there is a
population of House Finches in California that does show delayed plumage
maturation in males. During their first winter these young males show much
less colour than adults and it tends to be yellowish rather than red. I
don't have any first hand experience with these birds but heard about them
from somebody giving a talk. If I remember correctly it was the U. of
Washington student studying moult in _Passerina_ Buntings. I have no idea
where this population is to be found in the state.

BTW- lots of my House Finches at the feeder are yellow and I get them all
year round. Before coming here I had seen only one yellowish House Finch in
Vancouver.

Cheers

Al.


Alvaro Jaramillo "You are better off not knowing
Half Moon Bay, CA how sausages and laws are made"
alvaro at quake.net Otto von Bismarck,
but I saw it in a fortune cookie!

http://www.quake.net/~alvaro/index.html