Just Find the One With the White Head

I've heard it said that to find both Caspian and Yellow-legged Gulls at this time of year just look for the ones with the white heads - well it ain't that easy.

At Shawell, at the moment, there are some handsome looking adult Yellow-legged Gulls that are feather perfect, but there are also a few traps for the unwary (whoever the unwary are). Today I spotted an adult gull with yellow legs but something was not right about it, as far as YLG is concerned. Its legs and bill were not the right shade of yellow for me, its grey colouration was slightly too pale and its jizz was not quite right either. I considered 'yellow-legged' Herring Gull, but I would have liked to have seen a few dark streaks on its head at this time of year. I saw what appears to be the same gull in the afternoon and I could see that it had a few unusual dull dark markings - see the third photo down.

It is difficult to be sure but my gut feeling is that it could be one of the Dutch Yellow-legged x Herring Gulls. In the afternoon I saw a fourth-winter gull, which was similar, but it had much more white than black in its primary wing feathers. A couple of years ago Steve Lister and I saw a colour-ringed Dutch hybrid YLG at Shawell.

I'd be interested to get any opinions on this gull, as it is great to share thoughts on gulls like this. One thing for sure is that gulls keep things interesting and are always setting us challenges.

Possible Yellow-legged x Herring Gull

Possible Yellow-legged x Herring Gull

Note the Odd Markings Under the Tertials

Shortly after seeing the first odd looking gull I spotted the second-winter Casp x Herring Gull that I wrote about on 15/11/14. I saw it better this time and it was clearly a mixture of the two species, so I had been right to be suspicious of it in the first place.

At last, at about 11:00 a pure looking Caspian Gull appeared, but it didn't hang around for long. From what I could see it was a fourth-winter that I had seen previously.

Later on at the lagoons I spotted a clean white headed adult gull. Strangely enough it turned out to be another odd gull. Its bill was sort of Caspian like, but mainly in colour as it was quite short. Its eyes were pale, but not as pale as most adult Herring Gulls. Its wings were short and there was too much black on the longest primary (P10) for a Caspian Gull. It obviously isn't a pure Casp, so it's most likely a Casp hybrid or a very advanced Herring Gull - I favour a hybrid   Caspian x Herring Gull. 

So far this year I have seen 30 Caspian Gulls at Shawell that I consider to be OK, but I've also seen eight gulls that I consider to be hybrid Caspians. This is probably an accurate reflection of what we should expect in the UK, as the nearest breeding colonies are reported to have a similar percentage of pure compared to hybrid Caspian Gulls. Of course some of these hybrid type gulls are  impossible to be 100 % certain of their true parentage.

So if your looking for Caspian or Yellow-legged Gulls at the moment beware there are a few pitfalls to work through.