Friday 8th January comments: This week we’ve started a mini-series to bring you all the latest on our different seabirds which nest on the Isle of May National Nature Reserve (to lighten the mood at this difficult time). In our first featured bird; the Guillemot, we brought you the breeding biology, identification and the good news that the islands population has been increasing over the last decade. In the final chapter on Guillemots today we feature the species whereabouts at this moment in time, in mid-winter.
Guillemots breed on the Isle of May cliffs from April-July and as the summer progresses, the cliffs become bare and the Guillemots and young head out into the open north Sea. However after a two month absence, there is a noticeable return to Isle of May waters in October and soon after the birds start appearing on the cliffs from early November.
Various ongoing studies by Professors Mike Harris and Sarah Wanless of UKCEH indicate that birds return daily throughout the winter months to the cliffs usually from dawn for a few hours (and can be up to four hours) before heading back out to sea. This unusual behaviour involves birds in varying winter plumage and they return to cliff ledges occupied during the summer as the urge to establish and defend a good cliff ledge is far too strong, even in winter. It is also considered that this behaviour is also used to maintain their pair bond.
As the New Year and the new spring season approaches, birds will moult into their fine summer plumage and once again, the cliff ledges will be occupied by breeding Guillemots from early April to start the cycle all over again.