3rd Sep 2018: Caspian Gull?

John was out in the morning and at lunchtime and he and Colin were out in the evening today. In the morning there was a Teal, four Yellow Wagtails over and a Willow Warbler. At lunchtime John got on to a Wood Warbler in the tit flock on the south-eastern corner of the woodland, but unfortunately it was only seen very briefly. There was also a Black Swan and a Spotted Flycatcher.

In the evening there was a juvenile Yellow-legged Gull and what looked like a juvenile ‘Caspian Gull’. Fortunately, it was ringed (XEHA) so John could get a bit more detail on where it was from. It turns out it was ringed in a mixed colony in Germany at Gräbendorfer See. However, it turns out this is a mixed colony where it is not possible to identify the chicks with any certainty. The colony is mostly Caspian or Herring Gulls with some Yellow-legged Gulls and Lesser Black-backed Gulls and the existence of many hybrids (!).

Ian had a look at John's photos and added these notes:

I had a similar bird from the same colony at Didcot over the weekend - X544. Mine was a good cach in all respects except for the heavily marked scaps and the latters very advanced moult. I would guess mine might have had Yellow-legged Gull in its parentage. I think yours looks good apart from the heavily barred greater coverts and scaps so I would guess it's also of mixed parentage. Mixed parentage birds are becoming quite regular visitors to Didcot tip but I've had four pure Caspians in the last two weeks: a juv, 2 1st-s/2nd-w and an adult.

Photos courtesy and copyright of JFT

(YLG)