Return to the Isle of Puffins
Survey of bridled guillemots, 1959-60
Southern, H.N. (1962) Proc. zool. Soc. Lond. 138(3):455-472
The Common guillemot, or murre (Uria aalge) is a cliff-breeding auk distributed over the northern Atlantic and Pacific Oceans. In the Atlantic population a mutant form with a white eye-ring, called the bridled guillemot, occurs in a low proportion (1 to 6 per cent) at English and Irish colonies and this proportion increases northwards to a maximum of c.60 per cent in Iceland and Bear Island. This pattern of distribution was established by a co-operative inquiry sponsored by the British Trust for Ornithology in 193839.

Ten years later the survey waa repeated and at a substantial number of colonies the percentage of bridled birds had changed significantly, mainly in the direction of decrease. A recent re-survey after another ten years (196960) shows that the changes have been almost exactly reversed and the detailed evidence is presented in this paper.

Additional data from colonies in Norway and in Newfoundland and Labrador make the picture of distribution more complete.

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