Saturday, 4 December 2010

Caspian Gull (Larus cachinnans), ad, 2.-3.12.2010, Aarhus East Harbor

In flight the hand was slender and when seen from the underwing the black on primaries created a classic cachinnans boomerang.

This Caspian Gull has a classic small dark eye with a slight green peppering in the iris. When seen at some distance due to the peppering and the smaller size it stood out as being rather dark in contrast to nearby argentatus.

The white apical spots are all relative small and there is a unique step in distance between tip of p6 and p9 making this individual distinctive.

The upperparts are slightly darker than nearby argentatus which was obvious in both overcast and sunny weather.

In the stretched wing the grey tongues on the outer primaries are obvious.

There is a broad black band on p5, p10 has a isolated mirror and there is even a smaller mirror on p9 which is atypical for western Pontic cachinnans, but typical in more eastern bird within cachinnans populations. From time to time such birds with more black in wingtip than average are observed among Caspian Gulls all over their western winter range and at breeding sites in spring, even in the western Black Sea populations.

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