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The status and problem of the bridled guillemot
Southern, H.N. (1939) Proc. zool. Soc. Lond. A, 109(1):31-41
1. This paper summarizes the results obtained from the Bridled Guillemot Enquiry organized by the British Trust for Ornithology. It is hoped to carry on the enquiry during 1939.

2. The biological problems of most interest connected with the enquiry are (a) how isolation has occurred in a previously more homogeneous population to produce the cline in proportion of bridled birds now observable from south to north, and (b) upon what genetic basis such proportions are maintained.

3. The results are given showing increase from [less than] 0.25 per cent, in the south of England to 26 per cent, in the Shetlands, with two lines of discontinuity in the cline; beyond the British Isles the increase is continued up to 70-80 per cent, in the Westmann Islands, Iceland.

4. The question of the races shows another cline existing in Guillemot populations. There is not complete evidence to show that this is significantly correlated with the cline in bridling.

5. Previous work adds little but contradictions to the data gathered in 1938.

Keywords: none


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