Dead Bird Quiz answers

26 02 2014

Let’s delve into these, shall we? Bird A, I was very relieved to find, retained a tell-tale characteristic that vastly simplified this i.d.: the feet. The lobed toes with no webs between mark this bird as a grebe. What sort of grebe though? Here on the East Coast, we get three species turning up with some regularity: Pied-billed, Red-necked, and Horned. The feet won’t give us much by which to differentiate those three, so we must turn to other features. Wouter weighed in on this one, noting “It is medium sized with dark axillary feathers. Therefore, I think it’s Red-necked Grebe.” Wouter is basically never wrong, so let’s look at those aspects of this bird that he’s focusing on. The wing chord, making a guesstimate from the ruler in the photo, is somewhere around 16-17cm. The range for Horned Grebes is typically 13-15, and Pied-billeds smaller still at 11-14cm. Our Bird A is somewhat in between the range for Red-necked Grebe (at 18-21cm) and the smaller Horned Grebe. So, how can we make this call? As Wouter points out, the axillaries (or wing pit feathers) are dark in our Bird A. I have been staring at images of Horned Grebe and Red-necked Grebe underwings at the Slater Museum’s wing website, and am frustrated by a fair bit of overlap in their appearance; both species have darker feathers at the wing pit, variably with age and sex, it appears. Add to that that the specimen we have in Bird A looks to potentially have some twisted feathers near the wing pit where the orange tag is attached, so it’s possible that we are looking at the upper surface of those feathers rather than the under. The only other consideration I have here is the foot color. I don’t find a lot of definitive coverage of this, but in my experience, Horned Grebe feet are a paler gray than Red-necked Grebe feet, which makes me lean toward Horned Grebe for this specimen. On the other hand, the primaries look darkish gray, which tends to weigh more on the Red-necked side of the scale, as Horned Grebes tend to have a very white underwing overall. Persuade me, Wouter and any other Red-necked Grebe proponents!

Horned Grebe underwing

Horned Grebe underwing

Red-necked Grebe

Red-necked Grebe

Bird B takes the challenge of the Dead Bird Quiz to yet another dizzying height. This set of wings is in rough shape, but what we can tell is that they’re quite small, there appears to be a pale lengthwise band running along the upper surface, and there is a substantial amount of white on the underwing, particularly through the secondaries. I thought it might be some sort of shorebird, and Wouter did even better, going so far as to say it’s likely either a Semipalmated or a Wilson’s Plover. We don’t get many shorebirds in our SEANET database, so my experience identifying them is limited. These two species are quite similar, however, as detailed in a previous post, and in that case, we had additional parts to judge by–like feet. And heads. So perhaps with this one, we’ll go with “Unknown Plover.”

Forster's Tern in winter plumage (photo: BRian Gratwicke)

Forster’s Tern in winter plumage (photo: BRian Gratwicke)

Bird C will be a cinch for our southern contingent, but I include it because they’re still novel for me. It’s a tern, to be sure, and when confronted with terns, I often sigh and go take a coffee break. But this one is intact, so I actually stand a chance. Bird C has an faint orange tinge to an otherwise black bill, and some black on the head. From one angle, it looks more like a partial black cap with a white forehead, but from the other angle, it looks more like a black eye patch. That feature is what I latched onto, guessing that this is a Forster’s Tern (which is also what Janet Kurz, the finder, identified it as.) Wouter also concurred, citing additionally the white tail edges and light inner primaries to help clinch it. I like this bird for the DBQ especially because the dishevelment of the feathers over the head change the bird’s appearance substantially. This is a challenge we dead bird enthusiasts are accustomed to–plumage that makes the i.d. in a live bird may be substantially altered or even absent in a carcass. Luckily, there were plenty of other aspects of this bird that we could utilize. And I’m glad we all agree on at least one of these!




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