Introduction

The Glaucous Gull is a large, pale gull that has a circumpolar arctic distribution. In North America, it breeds along northern coasts in Alaska and the Canadian Arctic, east to Labrador. In winter, it is rare or uncommon south of its breeding range but does occur south as far as temperate maritime regions of California along the Pacific Coast and Virginia along the Atlantic Coast. Small numbers also winter regularly on the Great Lakes and the St. Lawrence River.

This gull nests in a variety of northern habitats, including open tundra, high coastal cliffs, islands in freshwater tundra lakes, and sandy islets at river mouths. It often nests in association with other colonial-nesting birds such as Black-legged Kittiwake (Rissa tridactyla), Thick-billed (Uria lomvia) and Common murres (U. aalge), Iceland Gull (Larus glaucoides), and Common Eider (Somateria mollissima). Glaucous Gull nesting density can range from single nests spaced kilometers apart over flat tundra to colonies of more than 300 pairs on islands and cliffs. This gull is socially monogamous, and each pair can raise up to 3 young in a season; the pair bond is often maintained for many breeding seasons.

A generalist feeder, the Glaucous Gull has a diverse diet that includes marine and freshwater fish and invertebrates, bird eggs and chicks, small mammals, berries, carrion, human refuse, and food items pirated from other foraging birds. One of these food categories may predominate in the diet of some individuals during the breeding season.

Compared with other North American gulls, this species is poorly studied, owing to the inaccessibility of its northern breeding locations and its thin distribution at coastal wintering areas. Recent studies in North America (Alaska and eastern Canadian Arctic) have focused on reproductive ecology (Strang 1976, Schamel et al. 1979), the identification of distinct races (Snell 1991b), foraging ecology and diet (Strang 1982, Gilchrist et al. 1998, Schmutz and Hobson 1998, Bowman et al. in press), and contaminant levels (G. Donaldson and B. Braune unpubl.).