Dead Bird Quiz answers

15 07 2010

What?! Only ONE guess on this week’s quiz? What are you all, on vacation?!

Bonaparte's Gull in flight. Note the prominent white stripe on the primary feathers.

Only the intrepid John Stanton offered a guess, and he’s 1 for 2. John correctly identified Bird A as a Bonaparte’s Gull. These Arctic breeders overwinter up and down the East Coast, and are found on lakes, rivers and ocean waters. They usually do not mix with other gulls, and will form large flocks where prey is abundant. They are smaller than most other gull species found by Seanetters. Distinguishing features of this gull apart from its small size are its thin, black bill and the conspicuous white triangle on the outer primaries.

Seanetters report very few Bonaparte’s Gulls, and even fewer of our Bird B, which was a terribly tricky specimen. Your SEANET blogger was stumped by this bird, and submitted it to our panel of experts, with the off-the-wall guess of a Sabine’s Gull (which would be almost impossible based on the time of year this bird was found). Cornell’s Marshall Iliff was first on the case, replying,

“This is not a Sabine’s Gull, since the feet are totally wrong in both color and shape (no webbing). In fact, this is an American Oystercatcher, which explains the wing pattern and the thick pink legs with prominent, rounded nails.
Oystercatchers occur in Maine only around Scarborough Marsh/Pine Point
Narrows/Stratton Island.”

Alternate view of Bird B, an American Oystercatcher. Note the lack of foot webbing and the white stripe on the upperwing.

This bird was, in fact, found on Scarborough Beach in Maine, falling within the limits of the only population of that species in the state.



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