Answer to Mystery Bird Quiz # 7

First off, thanks for all the responses to the mystery bird quiz. Below is the photo again to refresh your memory.


MYSTERY BIRD QUIZ

The top bird and bottom bird seem to be the best place to start in IDing these birds. Both birds are similar in size. Have rather long, slightly drooping bills, grayish heads, white belly, and black legs. Both of these birds are nonbreeding plumage Dunlin. The bottom bird is showing the white underwing, with gray tips to the flight feathers and the top bird is showing the gray upperwing with white area through the middle of the flight feathers. As far as the top bird potentially being a Western Sandpiper, the bill is a bit too long to be a Western and also the overall chunky look of the body doesnt agree with the slim look of a peep. Here is a photo of a nonbreeding Dunlin for comparison.

Dunlin (photo taken at Bald Eagle State Park)

Finally, the center bird with yellow legs. This bird is similar is size to the Dunlin; mostly gray and white; and has a black, drooping bill; but the yellow legs rule it out as another Dunlin. It has grayish armpits and a white supercilium. The first bird that comes to mind is a Lesser Yellowlegs. This species fits most of the descriptions, except Lesser Yellowlegs have a very straight bill without any droop and they are a bit bigger than a Dunlin, roughly 2 inches longer in length and 7 inch longer wingspan. Also Lesser Yellowlegs typically dont show such a profound white supercilium. Greater Yellowlegs can be ruled out also, because once again the bird is not nearly big enough and a Greater Yellowlegs bill is slightly upturned, opposite of the mystery bird. The only other North American species that fits the description is then the Stilt Sandpiper. This species is uncommon to rare in PA, but occurs occasionally during migration. The Stilt Sandpiper has a very obvious white supercilium in the adult nonbreeding plumage, yellow legs, and a somewhat long, drooping bill. Take a look at this photo of the same Stilt Sandpiper as in the mystery bird photo but in a standing posture.

Stilt Sandpiper

These photos were taken at the Kriner Road Water Retention Pond in Chambersburg, PA last October 25th. Ironically there was also a Lesser Yellowlegs present so below are some photos that compare the sizes and shapes of Dunlin, Stilt Sandpiper, and Lesser Yellowlegs. In the first photo notice the similar sizes of the Dunlin and Stilt Sandpiper, and the much larger appearance of the Lesser Yellowlegs. Also note the lake of an obvious white supercilium on the Lesser Yellowlegs. In the second photo, take a look at the severe size difference in the Stilt Sandpiper and the Lesser Yellowlegs, the lack of a white supercilium in the Yellowlegs, and the shape of each of their bills.

Stilt Sandpiper (left), Dunlin (center), and Lesser Yellowlegs (right)

Lesser Yellowlegs (left) and Stilt Sandpiper (right)

There were many responses, which made this more fun. Most responses I got said that they believed the the top and bottom birds to be Dunlin and they thought the center bird (with yellow legs) was a Stilt Sandpiper, so good job! Quite a few other responses thought the top and bottom birds were Dunlin, but considered the center bird to be a Lesser Yellowlegs. Some folks thought the top bird could be a peep of some sort, maybe a Western Sandpiper. Thanks so much for participating and I am very, very sorry for the poor quality of all of these photos, but I believe they were good enough to explain the identifications.

References:

Sibley, David. The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000. Print