Bill and Nancy LaFramboise wrote, about the Walla Walla hawk:

>This bird IS heavily streaked on the belly and chest. The light area is
>small and only just below the chin and appears to look more like some dark
>streaked feathers are missing and that more white feathers are showing. It
>is NOT the clear breast area seen on RTHA. It just has a little more white
>than the field guides show for the immature RSHA. In our opinion, the
>breast is not characteristic of a RTHA.

Umm, maybe the problem here is one of interpretation rather than fact. One
of the problems may be how we *describe* birds. Is the bird *streaked*
below or barred? Immature western Red-shoulders, as I wrote, are mostly
barred, or barred and streaked. Eastern birds are streaked, but not as
heavily marked. Red-tails are streaked for the most part, although the
legs are barred and there may be bars on the sides.

Some immature (perhaps only dark-morph) Red-tails can be so heavily marked
below as to essentially lack the clear breast characteristic of most of
them.

>The tail is barred but the light bars aren't as narrow as seen in the field
>guide pictures of the adults. They do look very much like the illustration
>of the immature western RSHA in the Nat. Geo. field guide.

If in fact the tail is dark with light (whitish) bars, that rules out
Red-tail for sure. My somewhat critical response was made in the absence
of information about this quite diagnostic characteristic.

>Although yesterday Tony saw this bird mostly flying, this morning it did not
>fly long distances. It spent its time going from one perch to another. It
>would hunt by dropping down to the ground from its perch. It is hard for
>us to comment on other aspects of its flight pattern. However, on Sunday we
>did see the bird briefly hover. Is this observation alone enough to rule
>out RSHA? If this bird were a RSHA and out of its normal range and in
>abnormal habitat, could it behave uncharacteristically?

If it were hunting in entirely open country, I suspect that might be the
case. I don't recall seeing Red-shoulders hover (my experiences with this
species were constant when I lived in Florida, but that's a long time ago,
and I see western birds only occasionally), but I wouldn't rule it out as
within their abilities.

>>As was pointed out briefly in the
>>kesstrel vs. sharp-shin thread, where a bird is and what it is doing are
>>very powerful parts of the field-identification process.
>
>We agree here. Powerful but not absolute. There are also birds that go out
>of range and we have had our share of them. We shouldn't have had a
>Steller's Eider nor a Heermann's Gull. One doesn't usually expect a Red
>Knot or a Red Phalerope, but they too have been here. A RSHA in is far less
>out of place than the Green-tailed Towhee currently in Rhode Island. More
>over, the location that it is in is river bottom / riparian growth, not
>prairie. This habitat is somewhat similar to the Ridgefield National
>Wildlife Refuge where a RSHA is currently being observed.

Sorry, here I didn't communicate well enough. I was talking entirely about
habitat and not range. Of course birds go out of range all the time, but
you still see a Steller's Eider or Red Phalarope paddling about in the
water rather than feeding in the shrubbery or in some other situation that
would be atypical of it. A Red-shouldered Hawk, being a woodland bird,
would probably head for a tree grove (as Don wrote) rather than hanging out
on the open prairie, and, again, your first message didn't convey that the
bird was in woodland.

>> Red-shoulders are considerably smaller than Red-tails, probably weighs
>from 50-70% as much.
>
>Clark provides the following weight and length ranges:
>
>RTHA: Weight 1.5 - 3.3 lbs -- Length 17 - 22 in
>RSHA: Weight 1.1- 1.9 lbs -- Length 15 - 19 in
>
>If these numbers are accurate, there appears to be overlap in sizes.

No, I don't think there's really overlap in what I call "size;" I've
handled dozens of dead Red-tails and several dead Red-shoulders and have
worked with large numbers of museum skins of both. Length measurements can
be terribly misleading, as when they are the same, they convey that birds
are the same size, when in fact they may be quite different in body bulk.
Tail length plays a part in this, as do erroneous measurements that may be
expressed in field guides. For a silly example, a Black-billed Magpie is
the same size (19") as a Red-shouldered Hawk, according to the NGS field
guide.

One reference for the two species (probably where Clark got his weights)
shows mean weights (females then males) of 701 and 550 grams for
Red-shouldered, 1224 and 1028 for Red-tailed. This shows that, sex for
sex, Red-shouldered is about 55% of the body bulk (=size) of Red-tailed. A
female Red-shoulder is 70% of the body bulk of a male Red-tail, so the
largest Red-shoulder would still be quite a bit smaller than the smallest
Red-tail. And the book (Palmer's Handbook of North American Birds)
indicates the weights for Red-shouldered were for northeastern birds;
western birds are smaller.

The wing area of a Red-shoulder is about 70-75% of that of a Red-tail, as
nearly as I can see by comparing them directly in our collection. Whenever
I see a Red-shoulder, I'm struck by how obviously smaller it is than a
Red-tail. Any other raptorphiles out there want to comment on this?

>We think that the reason people identified it as a RSHA is that the markings
>look very much like the RSHA shown in field guides and in other literature.
>In our opinion, this bird is on the very low end of the RTHA size range.
>The beak is less massive as are the legs/feet. The chest streaking is
>heavy. The white wing crescents are present and very visible from the
>underwing. There are no patagial marks. The tail is barred, upper and
>lower views. The wider light terminal tail band of a RTHA is not present.

The "white wing crescents" may be an oversold field mark for Red-shoulder.
I have in my hand wings of an adult of each species, and the Red-tail has a
far more conspicuous pale area at the base of the outer primaries than does
the Red-shoulder, from beneath; neither shows a wing crescent from above.
Many times I've noticed the pale primary base in Red-tails and wonder how
often people think they are Red-shoulders because of that. The lack of a
patagial mark is probably a good indicator that it's not a Red-tail,
although I've seen Red-tails in which this mark is not very distinct.

Parenthetical question here. How many observers go out and look at 100
Red-tailed Hawks and score the patagial marking as "conspicuous,"
"inconspicuous," or "absent," actually testing the validity of a classical
field mark? Has anyone out there in Tweeterland done this (I haven't, and
I'm one of the more persistent critics of the single-field-mark system).
The experts on hawks seem to be the first to admit how variable they are.
When you know what species it is, how often do you check each of its
attributes?

As far as tail markings go, I just looked at our substantial series of
immature Red-tails. About 10-20% have the terminal light band worn off,
mostly birds later in spring but including one midwinter bird. And,
interestingly, a few have dark bands as wide as the pale ones, so that the
tail could be described as "dark with lighter bands." I get my exercise
for the day when I'm writing these commentaries!

>In our opinion, there is enough here to suggest a RSHA. It clearly does not
>fit the norm of a red-tailed. Since it is out of range, we are trying to be
>careful and want to base our identification on more than just range. This
>is why we asked for more information.
>
>We plan on taking our own photos. At the very minimum, this bird is an
>interesting study and we DO NOT feel it should be dismissed yet.

I agree absolutely with you.

Dennis Paulson phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416