Reproduction and survival of Glaucous Gulls breeding in an Arctic seabird colony

Despite being widespread and easily observed, little is known about the life history of Glaucous Gulls (Larus hyperboreus). From 1984 to 2007, we examined their breeding biology and demography at Coats Island, Nunavut, Canada, where they nest alongside a colony of 30,000 pairs of Thick-billed Murres (Uria lomvia). The gulls fed mainly on murre eggs and chicks and by scavenging adult carcasses. The median age at first breeding was 5 yr, and the mean age was 4.8 +/- 0.9 yr. Adult survival was estimated as 0.84 +/- 0.03 (SE). The mean clutch size was 2.56 eggs and the mean number of young reared per year was 1.6 (range = 0.9-2.2). Birds reared at the colony provided 40% of recruits. Assuming that survival of locally reared chicks that emigrated was similar to that of chicks that returned to the colony, about 22% of the young gulls survived to breeding age. The timing of breeding by Glaucous Gulls appeared related to the timing of laying by murres. Although the demographic characteristics of Glaucous Gulls in our study were similar to those of populations of other large gulls, adult survival was at the lower end of the range for populations of large Larus gulls. There is some evidence that Glaucous Gulls exhibit lower survival than large gulls breeding in temperate areas, possibly because of contaminant burdens. In general, however, the demographic characteristics of large gulls show little variation and are probably a product of their common phylogeny.