Tagged Lesser Black-backed Gulls return to Orford Ness

Wednesday, April 18th, 2012

Species: Lesser Black-backed Gull

Project: Seabird-wind farm interactions - Orford Ness

Lesser Black-backed gull tagged with a GPS device (Photo: David Crawshaw)

Lesser Black-backed gull tagged with a GPS device (Photo: David Crawshaw)

On 20th February we received an exciting email from one of our volunteer gull ringers at Orford Ness – our first GPS-tagged Lesser Black-backed Gull of the year had returned to breed! Since then other gulls have come to join it, and fifteen tagged birds are now back (twelve tagged in 2011 and three from 2010). Last year all our tagged gulls migrated to wintering grounds in Iberia and North Africa. This year, we’ve seen some very different movements, with some birds going to Morocco, Spain and Portugal, but others staying in the UK for the whole winter – one individual did not even leave East Anglia!

These contrasting patterns are beautifully illustrated by our only tagged breeding pair of gulls, which were both fitted with GPS transmitters on 21st May 2011. The male in this pair spent most of his winter in Dorset, Hampshire and Somerset, primarily roosting in and around Poole Harbour on the south coast of England. His mate, meanwhile, opted to sun herself in Lisbon, Portugal. Intriguingly, these birds, that left Orford Ness in late summer, nearly met in late October, when the female was preparing to depart for warmer climes. On the afternoon of 28th, the female called in on Ibsley Water in Hampshire for about half an hour. Less than an hour later, the male was also there, having returned to roost after spending the afternoon on fields near Blandford Forum. However, our female had already left and was on her way south, missing a reunion with her mate by a matter of minutes!

Male and female gull tracks in Hampshire UK 28 October 2011

On the afternoon of 28 October 2011, the two birds' paths almost meet near Ibsley Water in Hampshire, with the female (shown in red on the figure) passing through around 15:30 and the male (shown in blue) coming in to roost for the night at 17:10.

Interestingly, none of the birds that stayed in the UK was tagged in 2010. All birds for which we now have two years’ worth of data took very similar routes and chose almost the same wintering destinations as they did during last winter. They therefore all ended up in Spain, Portugal and Morocco again. However, the timings were slightly different this year, with birds returning to the colony earlier than they did last spring. It is interesting to speculate about the reasons underpinning our gulls’ diverse migratory strategies. We hope our questions will be answered as more birds return, both to Orford Ness and Texel.

More information on this project can be found at:
http://www.bto.org/science/migration/tracking-studies/tracking-lesser-black-backed-gulls/march-2012-update.

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