Yellow-legged Herring Gull

After the exploits of yesterday I stayed closer to home today with a short walk up to Langelinie to look for gulls. Quite a few larger gulls around now (I guess more have come in due to the recent cold snap), mostly argentatus Herring Gulls. The highlight was this adult/near-adult yellow-legged Herring Gull. Quite a striking bird but definitely NOT a Yellow-legged Gull (michahellis) or Caspian Gull (cachinanns) given the structure and pattern of the wing tip (see third photo). Yellow-legged Gull (michahellis) should show a flatter head shape, peaking behind the eye, more attenuated rear, darker mantle and a 'mirror' on P10 (primary 10). Caspian (cachinnans) would show a smaller, darker eye, longer, thinner legs and a different pattern to the wing-tips (usually with an unbroken dark mark on P5).

So the only conclusion is that this is one of the small percentage of argentatus Herring Gulls that show yellow legs. A potential pitfall for the unwary!