Red-legged kittiwake  (Rissa brevirostris)

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).

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).

Found on the open ocean and breeds on vertical sea cliffs (4).

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).

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).

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).

• BirdLife International. (2001) Threatened Birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, UK.
• BirdLife International:
  http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3256&m=0

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