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Ivory Gull
last update: Feb 24, 2009 11:00 PM
Latin name: Pagophila eburnea
Longevity: 12-17 years
Population: 15,000-25,000
Cites classified: Near Threatened
Where found: It breeds in the high arctic and has a circumpolar distribution through Greenland, northernmost North America, and Eurasia.
Wingspan: 108-120 cm
Length: 40-43 cm
Weight: 448-687 g
Mating/Breeding: It breeds in the high Arctic north on coastal or inland cliffs up to 300 m high, on broken ice-fields or on bare, level shorelines with low rocks. The nest is constructed of moss, straw and other debris on a snow-free area of rock. Nest sites include broad upper ledges of steep, inaccessible coastal or inland cliffs up to 300 m high, broken ice-fields and bare, level shorelines with low rocks. On cliffs, pairs usually nest within 10 m of the top in small colonies with inter-nest distances of 1-20 m.
Eggs: Usually 1-2 bark to pale brown eggs with variable amount of dark spotting and blotching.
Hibernation: Winters along pack and drift ice in the Bering Sea and northward of Newfoundland. Also winter on ice along northern Eurasia
Migration: only short distances south in autumn, most of the population wintering in northern latitudes at the edge of the pack ice, although some birds reach more temperate areas.
Hunting Habits: It hovers, dips, and plunges into water to get food. It is attracted by red splashes on snow. It also follows whales and scavenges carrion from polar bear kills.
Feed on: It takes fish and crustaceans, but is also an opportunist scavenger, often found on seal or porpoise corpses. It has been known to follow polar bears and other predators to feed on the remains of their kills.
Predators/Threats: The species is thought to be declining due to changes in conditions on its staging or wintering grounds (e.g. more severe winters, changing sea-ice distribution and thickness). The species is hunted. Potential causes of the decline identified in Canada include illegal hunting, oiling at sea, disturbance of colonies due to escalating diamond exploration and/or increased nest predation, and toxic pollutants that bioaccumulate at high trophic levels. For example, concentrations of total mercury in eggs of Ivory Gulls collected from Seymour Island, Canada, have steadily increased since 1976 to levels which are now among the highest measured in seabirds, which may have had a long-term effect on breeding productivity.
Colour: adult has completely white plumage, lacking the grey back of other gulls. The thick bill is blue with a yellow tip, and the legs are black.
Interesting Trivia:
- The Ivory Gull casts up pellets of indigestible matter from its food, such as bones and fur. Pellet-casting is most frequent where lemmings are abundant and are the major prey.
- Large nests of the Ivory Gull are eaten by caribou during the winter and early spring.
