Saturday 6 December 2014

Caspian Gull Extravaganza

Four maybe five Caspian Gulls were at Shawell today. The first was difficult to clinch as the sun was hampering viewing at the landfill site. The gull did, however, appear ok, but I couldn't photograph it amongst the melee on the tip face, so I'm not happy to claim it for certain.

I joined Steve Lister at the lagoons and soon found a gull to flag up as 'an interesting one', this is the code Steve and I use when we find a Caspian Gull - long story. Its head and bill were spot on, but its legs looked a little short. Whilst it preened we got an extended view of P10 and this matched the correct pattern for Caspian Gull. Steve commented that its legs were pink, but I judged the legs to be pasty pink rather than bubble gum pink. In the paper on Identification of Caspian Gulls, Part 1 Typical Birds, Gibbins et al it states: 'There is complete overlap in leg colour between cachinnans and the Herring Gulls of the eastern Baltic (from pure pink to lemon yellow) so this feature is of limited value'

I have done a quick trait score on the bird and it scores within the range of pure Caspian Gull. The legs are unusually short, but there is great variation in leg length amongst the other large gulls, so there is likely to be variation amongst Caspian Gulls also.

Adult Caspian Gull

Shortly after Steve left to go in search of a possible Rough-legged Buzzard, I found a third-winter Caspian Gull, which I believe I first saw on November 19th. It has distinctive streaking on the back of its neck. The streaking is quite heavy but within the parameters for a third-winter in December.

Third-winter Caspian Gull

After finishing watching the gull above, I turned my attention to the gulls on the water and amongst them was another third-winter, one that I've seen previously. This one is more adult like than the previous one, but its tail still has most of the dark tail band.

Third-winter Caspian Gull

The final Caspian Gull had me thinking it was the same adult as the one with the short legs, but on inspection of the photographs it obviously isn't. The bill shape and pattern easily separate the two. This one was quite small, so possibly a female. Its legs were longer than the other adult as well.

Adult or near-adult Caspian Gull

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