Ivory Gull (Pagophila eburnea)
Given the ivory gull's harsh environment, it has several constraints on its population. Predators and weather are the most important limiting factors although human disturbance is also has a significant effect. At certain times in the breeding season, even a low flying aircraft can force the gull to abandon its nest!
The adults have white plumage which provides camouflage and warmth. They have smaller bills and shorter legs than other gulls of similar size- adaptations that conserve heat.
The ivory gull is the most Arctic of all the gulls, living in the far north year round. Its breeding grounds are confined to the High Arctic islands and coasts, and it nests in Siberia, northern Europe, northern Greenland, and northern Canada. In the winter, it stays with the pack-ice, rarely venturing south.
Ivory gulls breed in small groups, often on high cliffs where their eggs are safe from arctic foxes. They build bulky nests from any available vegetation, and usually lay two eggs. The incubation period is 24 or 25 days, and the chicks can fly about five weeks later.
In summer, ivory gulls feed on fish, crustaceans, and other marine organisms. They hover over the ocean surface until they find food, which they swoop down to grab. In the winter, their nourishment is attained through scavenging, scouring the ice for seal carcasses abandoned by polar bears and picking at the flesh left on the bones. In times of food scarcity, they will even eat polar bear droppings! There is no doubt that this birdís scavenging behaviour enables it to survive the harsh Arctic winters.