Breeding Biology of Crested Auklets at Buldir and Kasatochi Islands, Alaska

We quantified breeding parameters of Crested Auklets (Aethia cristatella) at Buldir and Kasatochi islands in the Aleutian Islands, Alaska, in 1996 and 1997. Crested Auk lets incubated their eggs for about 36 days and chicks weighed 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 linear phase (Buldir, n = 58; Kasatochi, n = 17), and chicks fledged at an average 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 hatching. We found no differences in and and intrayear chick growth for Buldir and Kasatochi. Productivity (the product of hatching success and fledging success) averaged more than 60% for the two years at Ka satochi and for eight years (1990 to 1997) at Buldir. Intercolony comparisons of productivity parameters revealed differences in hatching date, age of chicks at fledging, and hatching and fledging success. Adult mass differed significantly between the sexes (267 g for males, 253 g for females) and among years. At Buldir, we observed no effect of various levels of inves tigator 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 diurnally active species of auklets, grow relatively fast and depart at a younger compared with chicks of two nocturnal species of auklets.