Thursday, January 29, 2009

Glaucous x Herring Gull hybrid?

Yesterday when I searched through the Herring Gulls on the rubbish dump of Köping my eyes got stuck on a first winter gull. Seen from the front it was even coloured in a lighter shade than young Herring Gulls of the same stage. The bill was as dark as in Herring Gull with a hint of pink from the base to the nostrils. When it turned around and the primaries were shown I started thinking of a possible hybrid Glaucous x Herring Gull. They were not as dark as that of a normal Herring Gull and had quite broad light brown edges. Very much like the ones of the following gull, photographed by Chris Gibbins in Scotland this winter. Press here to see the image.
In the evening Hans Larsson noticed the light eyelids on the images, normally shown by Glaucous Gull.

The wing coverts had a lot of off-white markings and the scapulars weren't contrasting against the wing coverts. I don't know wether some were moulted or not. In the image to the left a few scapulars look moulted, but it's hard to tell. Sadly, I never managed to remember the appearance of the tertials and sadly the bird quickly dissapeared. From what I could see the bird had a tail-bar resembling that of a Herring Gull.

I can add that I saw a light gull in flight maybe ten minutes before I saw this one on the ground. It's quite possible it was the same gull. My impression of the gull in flight was someting like this presumed Herring x Glaucous hybrid (except for the red hue), press here.
By that I mean a light and diffuse appearance. But again, I'm not sure it was the same gull.

What suggest a hybrid on the standing bird is the pattern of the primaries, the even body colour and the very clear light eyelids.

Maybe you have experience of this kind of hybrids or just some thoughts? Write a comment!

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