The Ivory Gull is notable for exploiting remote and desolate reaches of the high Arctic. Its breeding distribution includes north-eastern Canada, northern Greenland, Svalbard, and several archipelagos in northwestern reaches of the Russian Federation. In winter is has a near circumpolar distribution, and is found in the Arctic, Pacific and Atlantic oceans. On occasion, at any time of year, it can be found far from drifting pack ice. In North America, this gull is confined to the central and eastern Canadian Arctic during the breeding season. Only rarely does it occur as a winter vagrant south of the Bering Sea and Maritime Provinces.
Ivory Gulls were known to Arctic mariners as early as 1609 ( Løvenskiold 1964 ), although the species was not classified formally until 1774 by C. J. Phipps, who described it from a specimen taken in Spitsbergen following an attempted voyage to the North Pole. In spite of a relatively early discovery, its mysterious lifestyle led to ample speculation about its habits. Some of the earliest assertions, such as a supposed aversion to sitting on the sea surface and reliance upon polar bear (Ursus maritimus) and seal offal, were certainly overstated. Even today, knowledge of the life history of Ivory Gulls has been slow to accrue and there have been no truly long-term studies of its demography.
The monotypic Pagophila exhibits distinctive structural, behavioral, and ecological differences from other gulls. Its bill is stout and rather long, while its legs appear shorter than in the similarly-sized kittiwakes (Rissa). Its feeding strategy and buoyant flight recall a Sterna tern, and it will nest on flat islands in colonies, as do terns. It will also breed on high mountain peaks and cliffs, however, more like kittiwakes, although its colonies are smaller and more dispersed. It has an unusually short period of immaturity for gulls of this size. Few other birds specialize in foraging within pack ice habitats. It is an opportunistic, aggressive, and voracious feeder, and in certain circumstances can be quite tame and easily approached by people.
In North America, the only intensive study of Ivory Gulls was undertaken in the 1970s by MacDonald ( Macdonald 1976 ) at Seymour Island, a Migratory Bird Sanctuary established in the Canadian High Arctic specifically to protect this species. Geologists discovered several of the colonies in Canada ( Frisch 1983 , Frisch and Morgan 1979 ), and these have been augmented more recently by population surveys designed specifically for this species ( Gilchrist and Mallory 2005 ). Contaminants in Ivory Gulls have also been examined recently, particularly in relation to their trophic level in marine food chains ( Campbell et al. 2005 , Braune et al. 2006 ). Overall, however, we continue to know little about its reproductive ecology, migration, over-wintering biology, or population size and dynamics.