Dead Bird Quiz answers

1 05 2012

Pied-billed Grebe has a very deep bill compared to its colleagues

Thanks to both Mary and Wouter for their answers this week; I am relieved that these two pros concurred with my own assessment of these specimens. All three of us pegged Bird A as a Horned Grebe and Bird B as a Razorbill. How did we do it, you ask? For Bird A, the first order of business was determining that this is a grebe. Luckily, the presence of the feet cements that i.d.–the grebe foot is unique in its large, lobed toes.

Horned Grebe's straight bill

Eared Grebe's slightly upturned bill

Within the grebes, there are several candidates on the east coast: Pied-billed, Red-necked, Horned, and, to a lesser extent, Eared. We can rule out the Red-necked Grebe right away based on size; the Red-necked Grebe is larger in all measurements than Bird A. Next, we can focus in on the bill shape. Bill length is similar between Pied-billed, Eared and Horned Grebes, but the Pied-billed has a much stockier bill with a far deeper base. That doesn’t fit with Bird A’s slender-based beak. So we’re left with Horned versus Eared. Eared Grebes have a much more western distribution than Horned Grebes, but they can certainly occur here on the east coast. While there are plumage differences between the two that can be helpful, many beached birds are too worn and disheveled for that. The trait I focus on is the bill shape. While subtle, the Eared Grebe’s bill is slightly recurved (upturned) while the Horned Grebe’s bill is straight and with a somewhat blunter tip. Thus, our Bird A, with its straight, non-recurved bill, has to be a Horned Grebe.

As for Bird B, the thin white stripe at the trailing edge of a black wing is the mark of an alcid. But which alcid, you ask? The answer is in the bill.

Razorbill in breeding plumage shows off its yellow mouth.

The lower bill has been torn away, and only an arcing upper bill remains. That prominent profile tells us this is a Razorbill. A small novelty is the striking yellow color to the mouth lining. While the Razorbill’s cousin, the Black Guillemot, gets a lot of press for the velvety red color of its mouth when calling, I argue that the murres and Razorbills should get some attention for that lovely yellow as well. You won’t see it often in living birds, since they rarely call outside the breeding season. But dead birds, with their habit of holding very still, give you a rare chance to see this vibrant pigment up close and personal.




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