Subject: Re: McNary buteo
Date: Feb 8 08:54:17 1996
From: Don Baccus - donb at Rational.COM


Bill and Nancy LaFramboise:

>While you are at it, there is another photo that Scott took that does not
>have the rufous coloring due to lighting/scanning conditions. This photo is
>a little closer to the real look of the bird. It can be found at
>http://www.wolfenet.com/~scray/rsha.html It is the fourth picture.

I've looked at these. I'm not quite sure what you mean. "rufous
morph", as you might guess :), aren't really rufous. Named by
birders, after all :). The immies are merely heavily streaked in
the belly and somewhat streaked in the breast, though nearly all
dark (black and rufous and those in between) morph redtails do show
contrast between chest and belly. As #4 photo demonstrates.

They get their rufous name because the chest becomes chestnut
when the bird is adult, while the rest of the bird tends to
go chocolate much like many not-quite-black-morph individuals
do. However, if you look closely at adult light-morph redtails
you'll see that their chests are pale chestnut - the rufous
morph adult chest is just an exaggeration.

>From the back, adult light, rufous, and many darker redtails -
excepting true black morph individuals - look about the same.
Dark-but-not-black-morph kids (including rufous) have many
narrow dark bands - adults may or may not show this in their
red tail at adult-hood.

Adult and immy rufous also have obscured or even missing patagial marks,
and the underwing coverts are chestnutty as well. But, again this
is just an exaggeration of the chestnut coloration seen on many
light-morph adults.

I must say that many light-morph adults in Western Oregon (and I'd
guess Washington, too) show very pale, whitish chests and very
pale underwing coverts with a highly contrasting patagial mark.
The intermountain birds we band and observe more often fit the
classic "western light morph" as described in Peterson's
Hawk book. Note that they're described as being "more richly
colored" that eastern lights, and as often having some barring
in the tail.

Maybe we should call these "more-rufous-than-normal morph" to
clarify things :) Portland Audubon has a beautiful edu-bird
which is an adult rufous-morph, a very dark one, too. Wish I
had a photo to scan! As a kid it looked much like the one
under discussion, but more heavily streaked in the chest, as
befits a bird which is dark as rufous morph birds go.

Of course, we also get redtails in the Goshutes that are almost
entirely white, especially immatures - perhaps a couple of spots
on a couple of belly feathers deliniating the "belly band" and
a couple of streaked feathers the "patagial mark".

These forms all interbreed like crazy, of course, so describing
these morphs is sort of like trying to describe human eye color!



- Don Baccus, Portland OR <donb at rational.com>