Survival of adult Common Guillemots Uria aalge at three Scottish colonies

We present the results of a mark-recapture analysis of survival rates of Common Guillemots with at least one year's breeding experience for birds from three Scottish colonies. Estimates of overall survival of adults from the Isle of May (North Sea), Canna and Colonsay (both off northwest Scotland) from an analysis combining data from the three colonies were 94.8% (se = ±0.6), 92.4% (se = ±0.9) and 96.7% (se = ±0.6) respectively. The rates from Canna (but not Colonsay) differed significantly from those of guillemots on the Isle of May. The Canna and Colonsay figures are the first survival estimates for guillemots in northwest Scotland, an area of high conservation concern for this species. Low input, long-term studies of seabirds can produce important data on adult survival.