Dead Bird Quiz answers

27 03 2012

Turns out you have to get up pretty early in the morning to fool devotees of the Dead Bird Quiz. Both Wouter and Dennis detected my ruse, that these three pictures represented fewer than three distinct species. In fact, as Dennis correctly answered, the first two birds were both Bufflehead (A was a male, and B was a female), and the last bird a Common Goldeneye. Both species are small ducks, with the Goldeneye’s wing chord ranging from 19-24cm, and the diminutive Bufflehead’s merely 14-18cm.

To walk through the i.d., what we have here are three dark wings, each with some degree of white on the upper surface. Alcids (murres, dovekies, and such) have a dark wing, but the white is limited to the very tips of the secondary feathers and does not extend over the wing’s upper surface. So those guys are out. That leaves the Red-necked Grebe and the small ducks (Bufflehead and Goldeneye). The Red-necked Grebe can be ruled out by the lack of a white leading edge in the crook of the elbow of the wing. RNGRs thus have two distinct white patches on the upperwing–one on the leading edge close to the body, and the other on the trailing edge farther out along the secondary feathers.

Red-necked Grebe: note two separate white patches on upper wing.

Male Bufflehead; white extends almost to leading edge of wing.

Female Bufflehead: note the limited white on upperwing versus male. (Photo by Mike Baird)

The best differentiating feature between our remaining candidates, the Bufflehead and Common Goldeneye, is size. Goldeneyes will invariably have a longer wing chord, if the measurements are taken very carefully. But if measurements are not available, then it can be a challenge to make the call between male Bufflehead and male Common Goldeneye in particular, if only the wings remain. In general, the white band on the upperwing extends a bit farther forward on the Bufflehead, but without having them side by side, that’s a tough comparison to make. All the more argument for taking careful, accurate wing chord measurements; it can be the difference between an i.d. and “Unknown duck” in the database, after all.

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