Friday mystery object #317 answer


Last week I gave you this unidentified bird skull from the Dead Zoo to try your hand at identifying:

mystery317

It seems that everyone recognised it as being from a charadriiform, and one of the waders at that. The first response was from Chris, who made reference to Lewis Carroll’s poem the Walrus and the Carpenter in which the eponymous characters eat an enormous quantity of oysters – hinting that this is an Oystercatcher.

There were some other suggestions that it could be from one of the birds in the genus Tringa, which includes the ‘shanks’ (Redshank, Greenshank, etc.), but the morphology fits one of the Oystercatchers better – in particular that weird constriction about halfway down the mandible when you look at the skull in profile.

This mandibular ‘waist’ is quite unusual and it doesn’t even seem to occur strongly in all of the Oystercatchers, which helps narrow down the likely species within the genus Haematopus, especially when you factor in things like the relative bill proportions, although you have to be careful doing this as there is some sexual dimorphism in the shape of the bill, with the females’ being longer.

The three closest species are the American Oystercatcher, the Sooty Oystercatcher and the Blackish Oystercatcher, but unfortunately I’ve not been able to find good reference skulls all of these species to be able to look for any distinguishing cranial characters. Based on bill morphology I’m leaning towards this being the skull of the American Oystercatcher, Haematopus palliatus Temminck, 1820.

American Oystercatcher by DonaldRMiller, 2010

American Oystercatcher by DonaldRMiller, 2010

My next step will be to check through our collections to see if we have comparative material to check the identification (once I get some time – a sadly rare commodity). If I can’t confirm I’ll just stick with Haematopus sp. on the label.

If you’re not familiar with Oystercatchers, they walk along the tideline either prying or breaking open bivalves. In my experience they seem more fond of mussels than oysters, but what do I know?

Another mystery next week!

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