Friday mystery object #397 answer


I’m going to start this week’s blog mystery object with an apology – it’s going to be a short one, as I’m in the final throes of taking down our Fin whale, which means I’m exhausted after several long weeks of hard graft. Check out the #DeadZooDiary hashtag on Twitter if you want to get an idea of what’s involved.

Last week I gave you this somewhat smaller skeleton from the Dead Zoo to have a go at identifying:

It wasn’t too difficult to narrow it down to one of a few species, thanks to the very distinctive knee region.

There are only a small number of birds that have adopted this extreme elongation of the cnemial crest on their tibiotarsus and patela. These are all specialist foot-propelled swimmers that need that long lever to help power their diving strokes. This is a feature limited to just the grebes and the loons/divers.

Most people figured out that this is the skeleton of one of the loons. The skull provides some clues, but unfortunately the angle of the photo doesn’t make it easy to figure out which of the five species it is.

The scale does rule out the larger of the species (Gavia immer or G. pacifica), but there are three other possibilities. For me the postorbital region suggests that this is the Arctic Loon Gavia arctica (Linnaeus, 1758), which fortunately matches the label.

I hope you enjoyed this weird kneed bird – congratulations to Goatlips and everyone else who figured it out!

4 thoughts on “Friday mystery object #397 answer

  1. Love the tibiotarsus/patella bit. New to me, though I knew this was the Arctic Loon from the skull. Thanks to Goatlips, I went to the Cornell site and listened to the “song,” which is weird and wonderful indeed, though I still vote for the Common Loon’s wail and laugh. Used to have a recording of it on my phone answering message. Too weird for most of my callers. Tried it to discourage the dozens of robocallers, but robos are immune to any lunacy except their own. Thanks for the fun!

  2. Certainly a loon indeed, but because of the upward angle of the lower beak it looks more like a red-throated loon (Gavia stellata) to me than an arctic loon (G. arctica). By the way, the two big loons are G. immer and G. adamsii. G. pacifica is the same size or a bit smaller than G. arctica.

    • I was looking at that bill and thinking the same. Once I have a bit of time I’ll take another more detailed look, but that will have to be after the whale skull has been finally dealt with! Thanks for the notes on G. pacifica, this is why I shouldn’t write when exhausted. When I can face turning on a computer I’ll correct!

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