Improving guillemot ledges

Published source details Corkhill P. (1970) Improving guillemot ledges. Seabird, 2, 46-47.
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Summary

Repair/support nests to support breeding

A before-and-after study in 1967–1971 on Skomer Island, Wales, UK (Corkhill 1970) reported that after modifying nesting ledges (by clearing vegetation and moving rocks), guillemot Uria aalge productivity increased. Statistical significance was not assessed. In the two years before modification, guillemots breeding on the studied ledges produced a total of 1–2 fledglings/year. In the two years after modification, this increased to 3 fledglings/year. In the third year after modification, four chicks and one egg were recorded, but these were not followed to fledging. The study focused on two ledges used by 5–7 pairs of guillemots. The ledges were modified in autumn 1968 by removing fringing soil and vegetation, moving large rocks to the edges of the ledges, and paving the floor with flat stones (angled to improve drainage). Productivity was monitored before (1967–1968) and after (1969–1971) modification.