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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Dead Bird Quiz becomes tournament of champions

13 02 2013
Our Bird A once looked more like this masked bandit.

Our Bird A once looked more like this masked bandit.

I’m glad I postponed this DBQ answer reveal, because we ended up with a wealth of responses. First to ring in was James Taft, suggesting Forster’s Tern for Bird A. Subsequent guessers Mary Wright and Wouter van Gestel concur, as do I. It’s a relatively easy thing to identify an intact carcass. For the dead bird enthusiast looking for pointers on this i.d., the Forster’s Tern (FOTE) is most likely to be confused with the Common Tern (COTE). Notable differences: in non-breeding plumage, FOTE have a dark “mask” encircling each eye with a lighter nape of the neck. The COTE, on the other hand, always has a black nape, and either a complete or partial black cap, depending on the season. Breeding FOTE also have a black cap, however, so in that case, the bill color can be of help. It’s dark orange-red in breeding COTE, and pale orange with a distinct black tip in breeding FOTE.

Bonus on our Bird A: it’s a species for which we needed pictures for the upcoming Field Guide, so I was doubly excited to see this one submitted to the database!

Is that you, Bird B? (Sooty Shearwater in flight)

Is that you, Bird B? (Sooty Shearwater in flight)

Bird B generated a collection of conflicting identifications from four contestants: Juvenile Laughing Gull (James)? Black Gull (Nancy)? Sooty Shearwater (Mary)? Greater Shearwater (Wouter)? This always unnerves me since I do not claim to be an expert at making these identifications and I always feel best when I get a roaring consensus. In this case, I did get a welcome opportunity however: a chance to try out the Wing Key I’m developing for the Field Guide. Following my own key lead me thusly: dark and unmarked upperwing? yes. underwing light? yes. Wing chord greater than or less than 15cm? (and I am aware I failed to give you this info, dear readers; it was 27cm) yes. Underwing light but with darker leading edge? yes.

So here’s where it got tricky. The next question in my key is “clean white central underwing? or “smudgy white underwing”? In our Bird B, the light underwing doesn’t look entirely clean white, which would lead us to an i.d. of Greater Shearwater. But it doesn’t look quite as smudgy gray as your typical Sooty Shearwater (the other likely option) either. Based on the wing chord of 27cm, I’d lean toward Sooty though.

Wouter’s point that the underwing just doesn’t look dark enough to be a Sooty is well taken however, and leaves me whipsawed with confusion. In this case, it may be the safest bet to call this one “unknown shearwater.” But if I’m bold, I may commit to Sooty. But I’ll choose “somewhat confident” on the dropdown menu if I do, you can be sure.