By far the most regular age groups of Caspian Gull at Shawell are first and second calendar year. This year juveniles were the most numerous in early autumn and now its mainly first-winters.
Today I saw four first-winters and one second-winter.
As I've probably said before, Caspian and Yellow-legged Gulls are usually born before Herring and Lesser Black-backed Gulls, so they advance quicker. Basically Caspian and Yellow-legged Gulls stand out because they replace their scapulars sooner than the other two species and they have often replaced some coverts before the end of their first calendar-year. The first one below has replaced one of its median coverts on the side visible in the photo. The next two have replaced many coverts including greater coverts.
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| First-Winter Caspian Gull, Cotesbach Landfill Site, November 4th 2017 |
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| First-Winter Caspian Gull, Cotesbach Landfill Site, November 4th 2017 |
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| First-Winter Caspian Gull, Cotesbach Landfill Site, November 4th 2017 |
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