Introduction

The Ivory Gull is notable for exploiting remote and desolate reaches of the high Arctic. Its distribution is circumpolar, or nearly so, breeding in northern Canada, Greenland, Svalbard, and several archipelagos stretching across northern reaches of the Russian Federation. It is rarely, if ever, found far from drifting pack ice at any time of year. 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. Its phylogenetic relationships with other larids has not been examined in detail and, unlike many colonial seabirds, 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 whereas its legs appear shorter than in the similarly-sized kittiwakes (Rissa). Its feeding strategy and buoyant flight recall a Sterna tern, its breeding colonies are smaller and more dispersed than in kittiwakes, and 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.