Monday, July 23, 2012

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