Wednesday 3 February 2016

First-Winter Caspian Gulls

So far this year I've done pretty well with Caspian Gulls and especially first-winter birds, which are my favourites.

Last Saturday I returned to Casepak recycle centre by the old British Shoe site in Braunstone, Leicester. I was hoping to get another chance to photograph the juvenile Glaucous Gull, but alas there was no sign of it. I spotted an immature gull with a very white head and underparts flying between the recycle compound and a nearby roof. I reacted quite quickly and managed to get a series of images of it. As I suspected it was a first-winter bird, but could it be identified from the photos? I placed a series of images on Facebook European Gulls group. I asked if it could be a first-winter Caspian Gull. Initially there were comments in agreement and then another group member asked why it wasn't a Yellow-legged Gull. I posted a better image showing the underwing a bit clearer. He quickly changed his opinion to most probably Caspian Gull. Another comment said he was concerned about the lack of streaking on the neck. I managed to find examples of Caspian Gulls with the same sparse amount of neck streaking. The go to Caspian Gull man said he thought it was most likely a Caspian Gull, but thought the tail was poorly marked.

After going through this process and searching through many photos I personally consider it to be a first-winter Caspian Gull. As I've said before there is a staggering amount of variation amongst immature gulls.

There is a considerable amount of overlap between Caspian Gulls and Yellow-legged Gulls. As a rule first-winter Caspian Gulls have whiter underwings, but there are some Yellow-legged Gulls of the same age with equally pale underwings. The combination of a pale window on the inner primaries with pale spots on the outer webs; pale grey mantle; small white head, the shape of the black tail band of the outer tail and the pale underwings all point to Caspian Gull. In some images the bill looks chunky, but in others it looks longish and parallel edged.  

Presumed First-Winter Caspian Gull
Presumed First-Winter Caspian Gull
Presumed First-Winter Caspian Gull
At Shawell I get a bit more time to study the gulls and the first-winter Caspian Gull in the video below posed nicely allowing me to record some decent video.

So for all you armchair gull watchers here's something for you to enjoy:

Best watched by clicking on the Youtube logo and switching the quality to HD.

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