Monday, 9 January 2012

Where there's muck ...

I could think of no better way of spending last Friday than being surrounded by gulls for hours on end. With a major influx of Iceland and Glaucous Gulls taking place after last week's Atlantic storms, I was hoping for a white-winger locally, but in the event it was Caspian and Yellow-legged Gulls that provided the main interest. At least four of the former comprised a first-winter, a third-winter, a fourth-winter and an adult, with the last two both being ringed. The fourth-winter bird was gold-on-green 355P, ringed as a chick in Poland and found by Jonathan Lethbridge and I at Rainham RSPB 14 months ago but not seen there since - great to have it back for another winter.

Back for another season, this fourth-winter Caspian Gull was ringed as a chick in Poland in 2008.
Note the distinctive primary pattern with largely white-tipped P10, big white mirror on P9, grey tongues on P8 and P9 and solid black band on P5. The primary coverts still have residual black markings.
The adult Caspian was the metal-ringed bird I saw last month. Despite getting close shots of it, however, I haven't been able to read any meaningful ring detail - if you can make anything out from these images, please post a comment. I suspect it was ringed overseas, not least because most gull-ringing schemes over here seem to colour-mark birds.




Yellow-legged Gulls were almost constantly present, and I decided to photograph every bird for a complete record. I estimated at least 14 individuals across all age classes, but having sifted through more than 900 images and compared fine bill and plumage detail, I was surprised to discover a minimum of 24 birds - four first-winters, nine second-winters, four third-winters and seven fourth-winters/adults. The range of variation within each age class was also surprising, and when time permits I will post a selection of images.

Plenty of other interest included an adult graellsii Lesser Black-backed Gull from a new ringing scheme (details hopefully to follow), and a very streaky-headed third-winter Herring Gull with a strong brown wash to the greater coverts, grey tongues to at least P8 (probably to P9, not sure about P10), a solid black band on P5 and a rather heavily marked blackish tail band for its age. As is so often the case with gulls, plenty of follow-up research to do ...

Third-winter Herring Gull with heavy head streaking and brown-washed greater coverts ...
... note also the primary pattern and blackish tail band at this age.
UPDATE: It was subsequently suggested that the metal-ringed adult Caspian Gull featured above may have originated from the Ukraine or Russia, but more recently it appears that it may have actually been ringed 13 miles east along the Thames at Pitsea, when it was mistaken for a Herring Gull (per Steve Arlow).

2 comments:

  1. Such a handsome bird, the Caspian

    ReplyDelete
  2. Its wouldn't be better then this because its truly an informative post. Thanks for the great work and keep going!!!

    ReplyDelete

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