Friday, 21 February 2014

Gull excursion

This fourth-calendar-year Great Black-backed Gull, ringed on an island off Denmark, teamed up with local Great Black-backeds on the River Thames today - its furthest south 'recovery' point.
In a good morning at my gull study site on the Thames today, seven species included two different second-calendar-year Iceland Gulls (more on those in a separate post), two Yellow-legged Gulls (second- and third-calendar-year birds) and this well-travelled Great Black-backed Gull (above left), bearing a distinctive Norwegian ring. The great thing about the Norwegian Colour Ringing Scheme is that you can obtain an instant history when reporting details of one of its birds.

As its online history shows, JW933 visited eastern Britain in its first two winters, but was always reported from Suffolk and hadn't been seen as far south as the Thames before. Other Norwegian birds have, though, including this distinctive leucistic bird photographed last month further east along the river. Recording and reporting colour-ringed gulls is curiously addictive and rewarding on a personal level, but also important to help build up knowledge of where 'our' birds come from. A mixed flock of wintering gulls somewhere like the Thames may be largely comprised of common species, but more often than not they're a mix of local birds and migrants from elsewhere, something difficult to establish without the use of colour rings.

JW933's longest journey yet.

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