Jerry, Rob, Jack and Tweeters:

I just looked for the first time at the great photos Jerry took of a very
light colored Buteo near Davenport, and I'd like to reopen the question of
the ID.

The first impresson is of course of a very light colored bird that makes
one think Ferruginous Hawk. But after a bit of a double take, I'm strongly
inclined to think it's an immature light-phased Red-tail. My reasoning is
as follows:

The tarsi show in the middle photo on his web site
(http://homepage.usr.com/c/composites/148051.shtml) and appear to be
completely bare of feathers. Ferruginous hawks NEVER have bare tarsi
(remember, their common name used to be Ferruginous Rough-legged Hawk);
Red-tails always have bare tarsi.

The light feathers are heavily marked with barring as seen in the third
(flight) photo. This is very typical of Red-tails, but never (to the best
of my knowledge) true of the Ferruginous. I checked our specimens
(including outstretched wings), and the many photos and illustrations in
many books (see list at end of this message), and they seem to strongly
support this point. If you hold up a Ferruginous wing so as to get strong
backlighting, you get very, very weak barring, nothing like the strong
pattern in Jerry's flight photo. But Red-tails show it strongly, as in his
photo.

The Ferruginous is said to never have a dark malar stripe (Clark and
Wheeler, pages 74,75). Jerry's bird has one that shows in both perched
photos, though it's not large. Again, I checked our collection, and the
various photos and illustrations: Ferrugies don't show it, some of our
light phased Red-tails do.

The white spotting on the dorsal side (wings and back) is more typical of
Red-tails than the Ferruginous. Immature light phased Red-tails commonly
have many such white/light spots; the Ferruginous Hawks rarely (?) do, so
far as I can determine from memory, photos, and our specimens. (Jerry's
bird shows more spotting than any I've seen in the photos, specimens, etc.,
but that doesn't make it more like a Ferruginous.)

Jerry's bird doesn't appear to be an immature Ferruginous for the reasons
above and also because it appears to have a barred tail (based on the
flight photo). A Red-tail has a barred tail, a Ferrugie doesn't.

If the bird was an adult Ferruginous, it would have a reddish back. Jerry's
bird doesn't.

If it was an adult Ferruginous, it would show dark red feathers overlying
the legs. This bird does show some red, but it's much lighter. I looked at
the specimens in our collection and I found that a few light phased
Red-tails show this much red on their legs. So, the light red in the photo
isn't diagnostic of adult Ferruginous, and is perhaps more typical of
Red-tails. (Some immature Ferrugies also have this light red color, though
more typically they are white.)

The white in the primaries of the outstretched wing looks like barring to
me (i.e. white bars crossing the entire primary), not panels of white (i.e.
white covering only the inner web of each primary, as shown in Clark and
Wheeler plate 12, and in our specimens). The white in Red-tail feathers
forms a bar as in Jerry's bird.

Regarding the dark streaking on the belly that Rob mentions, I agree that
it isn't typical of a Red-tail, but I think it is even less typical of a
Ferruginous. I can find nothing remotely like it among Ferruginous photos
and specimens, but we have in our collection two specimens of Red-tail with
streaks that approach it. Still, it is different than any we have or I've
seen.

On my monitor I can't see the underwing coverts well enough to tell what
the pattern is. I've seen individuals of both species that would give the
impression I imagine from the photo.

Jack mentions the wing shape (Ferrugies have longer, narrower wings than
Red-tails). True, but I don't think I can be sure of the wing shape from
the photo. And even if I could, I would note that immature Buteos have
longer, narrower wings that the adults. Thus, the difference between an
immature Red-tail wing and an adult Ferruginous wing is less than when
comparing adults of the two species. So I think this character is at best
iffy, in this case.

The size of the bill doesn't convince me either, after looking at our
specimens. Bills of Red-tails do indeed average smaller (less deep) than
those of the Ferruginous, BUT the bills of FEMALE Red-tails are thicker
than those of the males, and every bit as big (thick) as those of
Ferrugies.

The color of the bill doesn't work well either. Both species have yellow
bills, though not always yellow for Red-tails. On my monitor I can see
some yellow but I can't tell the extent or intensity; however, I don't
think it wouldn't make any difference if I could.

Finally, I should note again that Jerry's bird is very light colored, but I
have seen occasional Red-tails late fall or winter in eastern Washington
over the last 25 years that have been (from memory, now) approximately this
light; ones where you were forced to do a triple take to ID it.

Anyway, that's the gist of my thinking on this one. Comments???


Dick Johnson
Curator, Conner Museum of Zoology
Washington State University
johnsonre at wsu.edu


Sources consulted for photos, illustrations, &/or text:

Clark and Wheeler, 1987. Hawks. Peterson Field Guide Series. Houghton
Mifflin Co., Boston.

Wheeler and Clark, 1995. A Photographic Guide to North American Raptors.
Academic Press.

Ferrand, 1983. The Audubon Society Master Guide to Birding, vol. 1.
Alfred A. Knopf, NY.

Udvardy, 1977. The Audubon Society Field Guide to North American Birds,
Western Region. Alfred A. Knopf, NY.

Stokes and Stokes, 1996. Stokes Field Guide to Birds, Western Region.
Little. Brown and Co., Boston.

Dunne, Sibley, and Sutton, 1988. Hawks in Flight. Houghton Mifflin Co., Boston.

Johnsgard, 1990. Hawks, Eagles, and Falcons of North America. Smithsonian
Inst. Press.

Terres, 1980. The Audubon Society Encyclopedia of North American Birds.
Wings Books, NY. (photos pp. 508-9, 512-513)

National Geographic Society, 1987. Field Guide to the Birds of North
America, 2nd ed.

Peterson, 1990. Western Birds, 3rd ed. Peterson Field Guide Series.
Houghton Mifflin Co., Boston.