Quiz #460 (2012-3-05) Solution

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The picture is not of an ABA Code 5 species.

Solution by Tony Leukering

What's a day when one doesn't learn something? I like to avoid such days and, thanks to Peter Wilkinson, I have avoided that pitfall today.

This week's quiz bird is obviously a small gull (plumage and small, dark bill) and the caveat with the quiz photo precluded Gray-hooded Gull from being the solution. Once amongst the small gulls, we should check wingtip pattern to greatly reduce the number of options. In this view, we cannot see much of anything of the wingtip pattern, but we can see enough. The enough of which I write is the underside of the outermost primary (p10) on both wings and on both wings, those feathers are nearly entirely white. That means that this cannot be other than one of the species with white wedges in the wingtip. (As an aside, studying the underside of the wingtips in most gulls can be quite useful in arriving at an ID and one can usually manage such on a perched or swimming gull.)

Differentiating Black-headed and Bonaparte's gulls can be a mite tricky at times, but this view is not one in which it should be, and I note that no respondent went with Black-headed, though some missed the obvious separator. Bill color is often useful in discerning between the two species, dark reddish in the former, black in the latter. However, this color can be tricky to assess in some pictures and I would certainly be hesitant to rule out Black-headed on the strength of bill color on this picture! Throw in the difficulty in assessing mantle color (Black-headed's is paler than is that of Bonaparte's) and I would have been left with a single -- though excellent -- differentiating character. Our bird's nape is obviously gray; Black-headed sports a white nape (and crown) contrasting with the gray mantle.

This is where that new knowledge bit comes in. Peter Wilkinson pointed out that there is another clue, in the shape of the meeting of black tip and white body of p10 in the two species. Bonaparte's shows a smoothly curved meeting extending from the inner margin of the feather down toward the tip and to the outer margin of the feather (as on the quiz bird; see inset, below). With Peter's suggestion, I looked into the feature a bit and found that the meeting in Black-headed is rather straighter, cutting across the feather or, even, slightly back up the feather, such that where the white meets black on the inner margin is at the same distance from the tip -- or closer -- than where it meets on the outer margin. As Peter noted, I doubt that the character would be useful in the field, except under the most beneficial circumstances, but it seems to be readily assessable in photographs given an appropriate view.

I took this picture of an adult Bonaparte's Gull in North Cape May, Cape May Co., NJ, on 11 March 2010.

One respondent's answer was precluded from being correct for the competition as it neglected the "e" in the name of the species and another's was precluded as the "g" went uncapitalized.

Incorrect species provided as answers:
Ross's Gull - 1
Black-legged Kittiwake - 1

Congratulations to the 18 of 20 getting the quiz correct:
Ben Coulter
George Cresswell
Nick Komar
Logan Kahle
Tyler Bell
Margaret Smith
Robert McNab
Jim Nowjack
Al Guarente
Richard Jeffers
Josh Yoder
Su Snyder
Margie Joy
William von Herff
Peter Wilkinson
Kirk Huffstater
Bryan Guarente
Sean Walters

Answer: Bonaparte's Gull

Quiz #459 (2012-3-04) Solution

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Solution by Tony Leukering

A long, somewhat-lanky raptor dashes over a pond in front of two ducks. While the ducks may not have drawn much attention, they also did not confuse many of us. As is typical, the raptor did.

I will start down the solution road with the two ducks in the background. They appear to be quite similar to each other in size and shape, so might very well represent a single species. We can see the right bird's tail, which is mostly white. As we know from previous quizzes at this venue, a white tail in dabbling ducks (note the patterned body feathers that rule out virtually all diving ducks) means either Mallard or Northern Shoveler. The bill color would rule out all but the youngest juvenile Mallards (which do have black bills), but the yellow eyes rule out even that option. In fact, these three features leave us only Northern Shoveler as an option and the combination of bright yellow eyes and black bills indicate that both birds are adult males, despite their drab dress. The extensiveness of the white in the tail of the right bird also points in that direction.

The raptor is brown with paler underparts; a yellow eye; a relatively hooded look; and a longish, banded tail. Not knowing the actual distance from raptor to ducks, we cannot truly assess the raptor's size in relation to the known Northern Shovelers. However, those with a knowledge of photography will probably guess that, due to the fact that both the ducks and the raptor are in focus (or nearly so), that they are not all that far apart. That could mean that the raptor is not insubstantial, but let's try to back that assessment up with confirmatory features in order to truly rule out Sharp-shinned Hawk. Well, Sharpies only rarely show the strong hooded aspect shown by our quiz bird and features of the bird's head also support ruling out the smallest of ABA-area accipiters: the eye is placed far forward on the head and is small relative to head size; the crown is flattish with a long-sloped forehead. Additionally, the head is certainly protruding well beyond the leading edge of the wings. Finally, the tail just looks too long to be that of a Sharp-shinned Hawk.

The longish tail and its pattern rule out nearly all other non-accipiter options (as does eye color for a few), so we're left with Northern Harrier and the two large accipiters. Brown Northern Harriers have long, banded tails like that of our quiz bird, but the dark and light bands are of nearly equal width. Also, the quiz bird sports only the barest suggestion of the pale, median-covert bar sported by brown Northern Harriers.

We are now left with just the two big accipiters. Juvenile Northern Goshawks show white highlights to the dark bands on the tail and also sport wing bars created by pale bases to both the median and greater coverts and thin, white tips to the greater coverts; our quiz bird lacks all of these and does not sport the obvious pale superciliary of Northern Goshawk. While the presence of such a super would not rule out Cooper's Hawk, the lack certainly rules out Northern Goshawk.

I took this picture of a juvenile female Cooper's Hawk flying over Bunker Pond in front of two adult male Northern Shovelers in "non-breeding" plumage at Cape May Point State Park, Cape May Co., NJ, on 22 October 2011. I note here that virtually every time that I have seen a raptor mis-identified as a Northern Harrier, the bird was a Cooper's Hawk -- the two species can be remarkably similar in appearance and shape.

One respondent's answer provided incorrect assessment of sex of the ducks directly with the species determination, thus the answer was precluded from being correct for the competition.

Incorrect species provided as answers:
Sharp-shinned Hawk - 2
Northern Harrier - 2
Blue-winged Teal - 1

Congratulations to the 14 of 20 respondents getting the quiz correct:
Tyler Bell
Robert McNab
Logan Kahle
Al Guarente
Ben Coulter
George Cresswell
Don Jones
Thomas Hall
Richard Jeffers
Kirk Huffstater
Margaret Smith
Josh Yoder
Bryan Guarente
Sean Walters

Answer: Northern Shoveler, Cooper's Hawk