Friday mystery object #275 answer


Last week I gave you this bird skull to have a go at identifying:

mystery275

I must admit that I was a little mean, because although this didn’t have an identification, it did come with a little more information than I gave you – mainly that it was found on the Welsh coast and it had a black head.

This information probably doesn’t actually help as much as you might think, although it does help narrow the likely possibilities to birds from a particular geographical area and likely habitat type. Plus those with a black head of course.

Also, I realise now that there has been some perspective distortion between the scale bar and the skull, making it look shorter than it really is – when measured it was 83mm long. But it turns out that you didn’t really need the information anyway, as the clues from the skull were enough, even with a slightly dodgy scale.

A clue by joe vans alluded to the salt gland scars above the orbits, which indicate that is a marine bird. Flick Baker also hinted at a bird of the sea – a Common Gull, which fits the bill (if you’ll excuse the pun), but this skull seems a bit on the short side if you compare with the specimen on skullsite.com.

Common Gull (Larus canus) in winter plumage, by NotFromUtrecht, 2010

Common Gull (Larus canus) in winter plumage, by NotFromUtrecht, 2010

A bit closer in size was the suggestion by palfreyman1414 of Black-headed Gull, which would also fit with the note about the specimen’s head.

Black-headed gull at but not in the Antwerp Zoo, Belgium by Hans Hillewaert, 2008

Black-headed gull at but not in the Antwerp Zoo, Belgium by Hans Hillewaert, 2008

Daniel Calleri also suggested something closer in size and with a black head, but it was the Mediterranean Gull. You might think this is less likely given the additional information about it coming from Wales, but they now range over much of Europe and the British Isles.

Mediterranean Gull in Sweden, by Martin Olsson, 2007

Mediterranean Gull in Sweden, by Martin Olsson, 2007

However, both of these are generally a little smaller than this specimen. Richard Lawrence wrapped up nicely with the following:

Size is everything with salt glands like that… too big to be the smallest, to small to be the commonest, too bulky to be the one with the darkest head… I’m plumping for the one with three fingers…

…which is an allusion to Rissa tridactyla (Linnaeus, 1758) – the Kittiwake.

Kittiwake in Vardø, Norway by Yathin S Krishnappa, 2012

Adult Kittiwake in Vardø, Norway by Yathin S Krishnappa, 2012

Now, the Kittiwake skull on skullsite.com is a little longer and as you can see there is no black head on the adult bird. However, I agree with Richard and think that this may be a young individual, which would explain the slightly smaller size and the presence of a black(ish) head.

So thanks for all your suggestions – they’ve been really helpful in sorting through the options! More mysteries next week…

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