Monday, January 25, 2010
Click the picture for a larger view.
Answer by Tony Leukering
Though all respondents provided raptorial answers, the variety therein included eight species of three genera. Most went with a member of the large genus Buteo, despite the pointed-ish wings. This week's quiz bird is a bit backlit, the picture is a bit fuzzy, and the bird, itself, is in a disturbing state of wear and molt, but we'll just have to persevere!
Our bird's wings are fairly long, ruling out the accipiters, there is just too much pattern on various feathers for our bird to be any of the pointed-winged kites, and the wingtips are too pointed for the bird to be any of the round-winged kites. The wings are too short to be those of an eagle, and none of the vulture species are reasonable guesses, what with so much whitish mottling on the underparts. The beast is certainly not an Osprey nor a Crested Caracara. Some odd plumage of Northern Harrier might be considered, but "brown" individuals of that species have the darkest part of the underwing being in the wingpits, which may very well be our quiz bird's palest area, at least on the underwings. All this leaves us with the buteos and, considering the pointed-ish wings, falcons. Those are odd bedfellows.
As there are fewer falcons to consider than buteos, we'll start with falcons. Our bird's dark, mottled underparts are a non-match for nearly all ABA-area falcon species, with Gyrfalcon being, because of the large variability in that species' plumages, at least a forlorn hope. Yes, our bird has pointed-ish wings, but ogling the wingtip more closely reveals that it has at least three fingers, with the growing primary 7 (p7) probably to be a fourth finger. Falcons are not known for their fingers.
Moving on, taxonomically, but staying put plumage-wise, we can see that there is a vague swath of pale coloration in the wingtip, perhaps a suggestion of a window of a juv buteo. However, windows typically cross among primaries (as in Red-shouldered), they do not parallel primaries and this bird's pale area seems to travel down p8 and p9. So, though our bird is apparently a young bird (because of, in the words of Kevin Kerr, "its failure to match any adult plumage"), it has replaced enough primaries to mask or eliminate any window. That could have been tremendously helpful, as most of the commonest and widespread buteos (Red-shouldered, Broad-winged, Red-tailed, Ferruginous, and Rough-legged) sport windows as juvs. Note that this set of species also includes most of the species that exhibit polymorphism, that is, have multiple color morphs.
Though we still have quite a way to go, as we haven't ruled out that many buteo species, though Rough-legged is eliminated by that bird's windows at all ages, I'm going to take a short-cut. Looking at the middle primaries of the bird's right wing that have obviously been replaced -- at least p5-p7 -- we see feathers that are very dark. On most buteo species, the remiges (primaries and secondaries) are pale with variably dark subterminal bands. This results in the remiges being the palest part of the underwing in the darker species and the darker individuals of polymorphic species. That's certainly not true here and, in fact, it seems that these replaced feathers are the darkest part of the underwing. Ah, that is like a hot knife through butter, as there are only two ABA-area buteos that show that pattern: Swainson's and White-tailed. And, as White-tailed Hawks with white throats would not show such strong dark malar stripes and no White-tailed Hawks exhibit our bird's tail pattern, the quiz bird must be a Swainson's Hawk.
After four quizzes, nine are tied with perfect scores, including all three members of the Guarente clan and both Such boys.
Incorrect species provided as answers:
Red-shouldered Hawk - 1
Sharp-shinned Hawk - 1
Broad-winged Hawk - 2
Gyrfalcon - 1
American Kestrel - 1
Red-tailed Hawk - 1
Peregrine Falcon - 1
Congratulations to the 19 of 27 getting the quiz correct:
Answer: Swainson's Hawk