Quiz #334 (2010-1-05) Answer

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Answer by Tony Leukering

A big, all-white, long-necked bird with a black bill and black legs -- gotta be a swan. As noted by a couple of respondents, swan ID is rarely easy, a caution with which I wholeheartedly agree! However, we're greatly assisted this week by the fact that our quiz bird is an adult; I really dislike juvenile swans -- they're tough!

Though ID of adult swans is fairly straightforward, it can be a bit tricky with some individuals, particularly if the views we get don't include good profiles. Our quiz bird is in profile, but the bill is partially hidden and the posture does not provide an optimal assessment of structural features. Just to be on the safe side, I ran the picture by Steve Mlodinow (currently of WA), who probably studies more swans than >99.99% of ABA-area birders. Fortunately for me, he agreed with my ID.

I am restricting discussion of this bird to the possibilities that are Tundra and Trumpeter swans, as Mute Swan and Whooper Swan are fairly readily eliminated by, if nothing else, bill color.

On ID of adult swans, most of the important features to assess reside on the head, but include:

1) size (preferably with a good yardstick species in proximity),
2) shape of culmen (top edge of bill),
3) shape of the meeting of forehead feathering and bill,
4) relation of forward extent of feathering above the eye to that below the eye,
5) shape of meeting of cere and facial feathering around eye,
6) presence/absence of yellow on the bill,
7) shape of feathering edge at gape, and
8) shape of neck in alert posture.

While there are other features that are useful here and there, the above get at the most useful ones. However, on our quiz bird, we can throw out #s 1 and 8 outright (the bird is by itself and not in alert posture), #2 is not perfectly useful as part of the bill is hidden, and there are enough Tundra Swans lacking yellow on the bill such that #6 is not useful here. Granted, presence of yellow would have sealed the ID but absence is not helpful. Also, #3 is difficult to assess accurately without a head-on (or nearly so) view of the forehead.

Let's look at the remaining features individually.

4) The feathering edge at the distal edge of the forehead is not as far forward as is the feathering edge at the chin -- point to Trumpeter Swan.

5) The bird's eye is directly adjacent to the bare skin of the cere, with no feathering pinching in to nearly isolate the eye from the black of the cere and bill -- point to Trumpeter Swan.

7) The edge of feathering extending from in front of and below the eye to the chin is straight or very nearly so, without any distinct curve downward at the gape -- point to Trumpeter Swan.

Of these three useful features, #5 is probably the one most readily assessed correctly at distance, because it imparts a very different look to the whole face on the two species. This really is a card-carrying Trumpeter Swan, as close attention to the swan-head illustrations in The Sibley Guide will attest.

I took this picture of an adult Trumpeter Swan in February 2006 in the Skagit area, Washington, where Steve M. tells me Trumpeter Swans regularly root around in muddy ag fields, while Tundras don't often do so. Of course, I've seen Tundras rooting around in fields in Maryland this winter, but.... Finally, to answer an indirect query by one respondent and to try to put to rest the misinformation of a previous age, both native swan species have salmon edges to the mandible; it is not an ID feature.

I suppose that the respondent providing a non-swan species in the answer (that person did get the swan correct) must have interpreted some of the stubble incorrectly.

Incorrect species provided as answers:
Tundra Swan - 8
Stilt Sandpiper - 1

Congratulations to the 21 of 30 getting the quiz correct:
William Velmala
John Bissell
Tyler Bell
Al Guarente
Tony Ferdensi
Chuck Carlson
Tom Wilberding
George Cresswell
Kevin Kerr
Mark Dettling
Andy Dettling
Aaron Brees
Peter Burke
Peter Wilkinson
Marcel Such
Nick Komar
Barbara Deneen
Joel Such
Chris Warren
Andrea Smith-Guarente
Bryan Guarente

Answer: Trumpeter Swan

Quiz #333 (2010-1-04) Answer

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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:
John Bissell
Nick Komar
Mark Dettling
Joel Such
Chris Warren
Chuck Carlson
Kirk Huffstater
Aaron Brees
Kevin Kerr
Marcel Such
William Velmala
Al Guarente
Peter Burke
Peter Wilkinson
Joe Bens
Thomas Hall
Bryan Guarente
Andrea Smith-Guarente
Chishun Kwong

Answer: Swainson's Hawk