Biology
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The red-legged kittiwake breeds in colonies on sheer cliffs (4). They arrive at the breeding colonies in April and depart in September, dispersing to the south over the open ocean over the north-east Pacific and as far east as the Gulf of Alaska (4). A single brood, consisting of two eggs, is produced each breeding season. The eggs are incubated for 23 to 32 days, and the chicks fledge at 38 to 48 days of age (3).
Feeds on small fish (such as lampfish), marine invertebrates, including squid, and on carrion (4) (3).
Conservation
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Many of the Alaskan breeding colonies are protected by the Alaska Maritime National Wildlife Refuge. Furthermore, on the Pribilof Islands a rat prevention programme is underway (4). There is a need for a long-term monitoring programme in order to detect any changes in numbers in the breeding colonies and the threats facing the species must be better understood, in particular the impact of fisheries needs to be established (4). It has been proposed that a buffer zone should be set up around the Pribilofs, in which fishing would be controlled (4) (2).
Description
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The red-legged kittiwake is a smallish gull, easily identified by its scarlet coloured legs (2). Adults are largely white in colour but the back and the upperwings are dark grey. The wings have black tips, and the yellow bill is short (3). Juveniles and birds in their first winter have more black feathers on the outer part of the wing, and can appear similar to the immature stages of other species of gulls; they can, however, be distinguished by their solid white tail (3). The only species that adults may be confused with is the black-legged kittiwake, but as the name suggests, it has black legs (2) (3).
Habitat
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Found on the open ocean and breeds on vertical sea cliffs (4).
Range
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This species breeds on islands off Alaska, USA (Pribilof, Bogoslof and Buldir Islands) and on the Commander Islands, Russia (3) (2). The total population was estimated to number 259,000 individuals in the 1970s, but this figure had fallen to 168,000 by 1990. Most of this decline occurred on the Pribilofs, but there was also a possible slight decline on the Commander Islands (4). The population seems to have stabilised recently (4).
Status
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Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).
Threats
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Although the reasons for the decline of this species are not fully known, it is thought that it may be the result of commercial over-fishing that has reduced food availability (2). A recent development was the construction of a harbour in the Pribilof Islands, which greatly increases the risk of rats being accidentally introduced to the islands. Predation by rats at the breeding colonies would pose a very serious threat to the red-legged kittiwake (2) (4).
Red-legged kittiwake
provided by wikipedia EN
The red-legged kittiwake (Rissa brevirostris) is a seabird species in the gull family Laridae. It breeds in the Pribilof Islands, Bogoslof Island and Buldir Island in the Bering Sea off the coast of Alaska, and the Commander Islands, Russia and spends the winter at sea.
Description
Red-legged kittiwake parent and chick.
The red-legged kittiwake is a very localised subarctic Pacific species. Apart from the distinguishing feature implicit in its name, it is very similar to its better known relative, the black-legged kittiwake; other differences include the shorter bill, larger eyes, a larger, rounder head and darker grey wings, and in the juveniles, which barely differ from the adults, lacking the black tail band and 'W' across the wings of juvenile black-legged kittiwakes. Juveniles take three years to reach maturity. Adults are 35–39 cm (14–15 in) long, with an 84–92 cm (33–36 in) wingspan and a body mass of 325–510 g (11.5–18.0 oz).[2]
Like the Pacific race of black-legged kittiwake, the red-legged kittiwake has a well-developed hind toe. As occasional individual black-legged kittiwakes have reddish legs, any reports of red-legged away from the subarctic Pacific must record all of the other differences, not just the leg colour, for acceptance by bird recording authorities.
Behavior
The red-legged kittiwake feeds on fish such as lanternfish (Myctophidae), squid and invertebrates. It spends the summer at the cliff breeding colonies, nesting on ledges, and migrates out to sea in September to overwinter in the north western Pacific Ocean and the Gulf of Alaska.[3]
Status
This species is listed as "Vulnerable" by the IUCN as its population appears to be in decline. It has a global population in the region of 337,000 to 377,000 mature individuals and its breeding range is 192,000 square kilometres (74,000 sq mi). Its numbers are thought to have decreased by about 35% between the mid-1970s and the mid-1990s though numbers may have stabilized since. It is unclear why they have declined, but it may be related to a change in the availability of prey, possibly associated excessive commercial fishing or with climate change.[3]
Gallery
Alaska SeaLife Center in Seward, Alaska
Alaska SeaLife Center in Seward, Alaska
Red-legged kittiwake chick
Red-legged kittiwake colony, St. George Island, Alaska
References
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Red-legged kittiwake: Brief Summary
provided by wikipedia EN
The red-legged kittiwake (Rissa brevirostris) is a seabird species in the gull family Laridae. It breeds in the Pribilof Islands, Bogoslof Island and Buldir Island in the Bering Sea off the coast of Alaska, and the Commander Islands, Russia and spends the winter at sea.
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