Just a pile of bones? Don’t despair!

18 03 2010

Sue Bickford of Maine found this shabby bone pile this month.

Not uncommonly, Seanetters find not a complete carcass, but a rather degraded pile of feather and bone. Crucial parts like the head and feet are often missing, and a Seanetter would be forgiven for thinking that identification is all but impossible in such cases. Not so!

In the case of the bird pictured here, all that remained were the sternum and wings. The sternum alone can give a surprising amount of information. In this photo the furcula (the two fused collarbones also known as the wishbone) is tagged with an orange cable tie (thank you, Sue!). That furcula appears to connect to the keel, which is the sharp ridge of bone on the otherwise flat, shield-shaped sternum. That connection between furcula and keel is characteristic of pouchbills (pelicans and cormorants and the like).

A cormorant's keel (the triangular ridge of bone) and furcula (the curving bones sweeping backward at left) are connected.

Compare with a Herring Gull where there is a gap between the furcula and the keel

The lesson here: if you find a jumble of bones, we may be able to tell what the bird once was if you take a few good pictures. Some guidelines: try to take your photos from directly above the bone and then directly through the side (angled photos can distort the anatomy). Your SEANET blogger does not pretend to expert knowledge of the subject, but can often give an idea of at least the species group to which your bony specimen might belong.

For an excellent site on seabird bone anatomy, please visit Edward Soldaat’s seabird osteology page, from which the two photos of sternae shown here were borrowed.

We welcome any and all bone photos, so don’t be shy about submitting them–they may be the key to the i.d.!

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