5 Aug 2012

Esophageal diverticulum

Just got back from a week in sunny (very!) Majorca. Not much birding done but a bit to much eating and drinking with the occasional forays into the sea for a bit of diving. A few birds seen though with the highlight being a flock of around 10 Audoins Gulls (with young) on a rocky headland south of Cala D'Or. The pines surrounding the beaches were full of Sardinian Warblers and the hotel grounds teemed with Spotted Flycatchers. I took this photo a few weeks back but had forgotten it was on my phone until I came to download some holiday photo's this morning. It shows a young Linnet on Hilbre with seeds stored in an esophageal diverticulum at the back of its neck!

I know other finches, such as Redpolls, have such an adaptation to enable them to store seeds to digest at their leisure later but it s the first time I've seen it in a Linnet. The esophageal diverticulum is a specialised 'pocket' of the midthroat that is used to store additional seeds and allows the birds to
make the most of a locally abundant food supply. In this case it looks as if its seeds from grasses or sorrel.

Amazing stuff.

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