Posted: Sunday 17th July 2016 by Twheatear

The interest of colour rings...

On the beach in Caithness last week, we spotted that one of the great black-backed gulls was wearing a yellow plastic ring, with the code H45, on its right leg. I failed to note whether the ring was above or below the knee, but the European Colour Ringing website had details of three studies of gulls matching that description, only one of which had used the code H45. So from that we knew that our gull had been ringed in Caithness, as a nestling, in 2010.

That might sound like an uninteresting stay-at-home bird, but a very quick response from the project coordinator tells a different story. The advantage of colour rings is that birds can be reported from casual sightings like ours: unlike traditional metal rings they don’t need to be recaptured or found dead for their locations to be discovered. And it turns out that H45 has been spotted five times: in September 2010, less than three months after leaving the nest, it was in Cornwall; in December 2012 it was in the Nevern Estuary in Pembrokeshire; and in February and December 2015 it was back in Cornwall, in the Camel Estuary. Now it’s back in Caithness, just three kilometres from where it hatched six years ago.

So has H45 spent its youth in the furthest corner of the UK from its home and  now, as an adult, returned to breed? Possibly, but it’s interesting to note that all the southern sightings have been in the autumn and winter. So perhaps this isn’t its first summer back in Scotland, and it has been making annual migrations from (nearly) John O’Groats to Lands End in at least some of the intervening years.

Keep an eye out for colour rings and report those you see, and you might help to answer that, and many other questions. Thanks to Mark for the information about H45, and to Dirk Raes for maintaining the European ringing project listings.

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