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Unidentified Piping Objects

April 10, 2008

You don’t have to have been long in the birding game to realize that there are some groups that pose particular identification problems in the field. Interestingly, my time volunteering in the bird lab at the North Carolina Museum of Natural Sciences has been largely taken up by breaking down some of the mysteries in these groups. Gulls, jaegers, Myiarchus flycatchers (that one was all my doing admittedly), and now Calidris sandpipers.

The genus Calidris or, as their commonly refered to, peeps, are a group of smallish highly migratory shorebirds characterized by their uniformly cryptic coloration, high energy, and propensity for inducing hysteria in birders. And rightly so, they can be difficult little birds to get to the bottom of, even for birders with lots of experience. But I’m not here to add anything to that already deep well of knowledge that exists with regards to peep identification. There is nothing I could really say that hasn’t already been said. In fact, if you’re interested, this most excellent article from Surfbirds by Cameron Cox opens that case, then shuts it, locks it, and deftly files it under “Difficult Bird IDs, Elegant Solutions to”. It’s that essential.

No, I only mean in this post to ease the fears of those who may feel lost by shorebirds on those distant mudflats and beaches, because sometimes, birds in the hand are no easier. This is the tale of my recent assignment to the “Drawer of Death”. Named not so much for the fact that it is full of dead birds, because that doesn’t make it particularly special in a room of dead bird cabinets, but because it contains the unknown Calidris. The birds that, even though far nearer than those distant mudflats, remain a mystery. Ladies and gentlemen, I give you… the drawer…

The birds were by and large Western and Semis, the two species of peeps that seem to cause the most trouble to birders, and for good reason. There is a lot of overlap between the two, especially with regard to bill length, a long-billed female Semi may look quite a bit like a short-billed male Western. I should point out that much of what we know about field identification of peeps is relatively recent, and so the birds that were still mysteries in the NCSM collection were largely older birds that had sat unchecked in the drawer for years rather then any individuals that were baffling to the excellent ornithologists at the museum. But to get an idea of what I had in front of me check out the picture below, one is Western, one is Semi. Can you tell which is which?

See how close they can be? Incidentally the top is Western and the bottom Semi. Fortunately, I had some tools at my disposal that the average field birder is unable to use. The calipers, for instance, a measuring device that enables you to make the fine distinctions in bill length, were indispensable. The range of bill lengths for the Western/Semi complex are pretty well established, and having such a tool allows you to have the quantitative outlook to go along with the often misleading qualitative view, or rather, just eyeballin’ it. As you can imagine, most of these birds were along the outliers, so in addition to the bill length I’d look at wing length where Semis tend to be on the long end here. Makes sense really, they migrate farther.

So in the end I had mostly Western or Semi with a couple mislabled Leasts thrown in for good measure. Leg color tends to fade in older bird skins so the Least’s legs, normally an excellent field mark in live birds, tends to shade a very dark green in dead ones. I did, however, come across a bird that remains unidentified, you can see it below.

I suspect it’s a Semi, but the bill and wings were both quite a bit shorter that what one could expect. Shorter even than the literature says for Least. It’s a puzzle to be sure, and I’m not really willing to indulge in dreams of pulling out a first NC record of some rare shorebird from the collection, despite the latent desire to do so. So until someone more comfortable with funky shorebirds comes along to take a look, unidentified it will remain.

So take heart, you who despair at the sight of packed mudflats. Sometimes even the bird in hand is no easier.

  1. John permalink
    April 10, 2008 9:11 am

    I notice that the birds in the second picture still have very different-looking bills even though the length is roughly the same. That, at least, is somewhat encouraging.

  2. April 10, 2008 10:17 am

    You’re right John. The base is much thicker in Western and the culmen tends to show a bit of downward curve. Whereas Semi, even when it’s abnormally long, tends to be straight and a little bulbous on the tip.

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