Breeding biology of Crested Auklets at Buldir and Kasatochi islands, Alaska

We quantified breeding parameters of Crested Auklets (Aethia cristatella) a t Buldir and Kasatochi islands in the Aleutian Islands, Alaska, in 1996 and 1997. Crested Auklets incubated their eggs for about 36 days and chicks we ighed about 35 g within the first three days of hatching (14% of adult mass ; Buldir, n = 58). Growth rates averaged about 9.9 g per day during the lin ear phase (Buldir, n = 58; Kasatochi, n = 17), and chicks fledged at an ave rage mass of 248 g (95% of adult mass; Buldir, n = 63) and a wing length of 123 mm (88% of adult wing length; Buldir, n = 37) at 34 days after hatchin g. We found no differences in intraisland and intrayear chick growth for Bu ldir and Kasatochi. Productivity (the product of hatching success and fledg ing success) averaged more than 60% for the two years at Kasatochi and for eight years (1990 to 1997) at Buldir. Intercolony comparisons of productivi ty parameters revealed differences in hatching date, age of chicks at fledg ing, and hatching and fledging success. Adult mass differed significantly b etween the sexes (267 g for males, 253 g for females) and among years. At B uldir, we observed no effect of various levels of investigator disturbance on hatching and fledging success or on other breeding parameters. We found no negative relationships between hatching date and fledging age, hatching date and fledging mass, or fledging mass and fledging age, contrary to the predictions of Ydenberg's (1989) model of intraspecific variation in timing of fledging of alcid chicks. Crested Auklet chicks, like those of other di urnally active species of auklets, grow relatively fast and depart at a you nger age compared with chicks of two nocturnal species of auklets.