Tuesday, 1 October 2013

Red-legged kittiwake

Rissa brevirostris

Photo by Doug Sonerholm (Flickr)

Common name:
red-legged kittiwake (en); gaivota-tridáctila-do-Pacífico (pt); mouette des brumes (fr); gaivota piquicorta (es); klippenmöwe (de)

Order Charadriiformes
Family Laridae

This species is found in the northern Pacific ocean, with breeding colonies around the Bearing sea, in the Pribilof, Bogoslof, Budir and Aleutians islands of the United States, and in the Commander islands of Russia. They wander in the Pacific between parallels 35º and 62º N.

This small gull is 35-40 cm long and has a wingspan of 84-92 cm. They weigh 325-510 g.

The red-legged kittiwake is a pelagic predator, foraging in the open ocean and breeding in vertical sea cliffs and rocky offshore islands.

They feed on small fishes, namely lampfish and pollack, as well as squids, small crustaceans such as amphipods and carrion.

Red-legged kittiwakes breed in April-September. They breed in colonies, nesting in a shallow cup of mud, grass and kelp placed on a ledge in a vertical cliff. The female lays 1-2
grey to buff or greenish eggs with brown blotches, which are incubated by both parents for 23-32 days. The chicks are fed by both parents and fledge 38-48 days after hatching.

IUCN status - VU (Vulnerable)
This species has a relatively large breeding range and a global population estimated at 337.000-377.000 individuals. From the 1970s to the 1990s the population declined by 35 %, a trend which as since stabilized for a total decline of 30-50% over the last 4 decades. The reasons for the population decline remain unclear, but it has been attributed to a reduction in food supply resulting from excessive commercial fishing. Shifts in the distribution of prey fish species, resulting from climate change and rising sea temperatures, may also contribute to current and future declines, while climate change may also have a direct impact on this species which as a breeding range restricted to within 10º latitude from the polar edge. There may also be some impact of subsistence hunting in some islands. If rats reach the islands where they breed they could pose a further threat, so a rat prevention programme is underway in the Pribilof Islands

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