Adult Caspian Gull Viksletta, Halden

Near dusk yesterday, I came across a large congregation of gulls on a flooded field at Viksletta, Halden. Well worth a try, I thought, and was rewarded with this adult caspian gull. Unfortunately I only had the phone to document it with (through a swarowski telescope), so the results are not award winning material...Note that the bill tip was covered with dirt, making the bird look like belonging to a younger age group. In the field it showed e.g plain grey primary coverts, indicating adult. Slivers of grey eating into the black in the primaries on the upper hand consolidated the id.

 White head, dark eye, greenish bill with hardly any gonys angle. Small bird, so probably female.

Females are not as extreme as males, and a small female like this has an almost common gull expression, owing to the dark eye and rounded head shape.

On this picture, you can see (on the far wing) a long white tip to P10 and a silvery white "tongue" on the inner web eating its way from the base far out towards the tip, leaving a narrow portion of the feather (inside the white tip) black. This individual has a peculiar light spot in the black.

Note how the border between the silvery white tongue and the black is almost 90 degrees. This is a strong caspian gull feature. On most herring gulls, the white tongue tapers and becomes progressively more narrow. Se cropped picture below.