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Black-legged Kittiwake

Black-legged Kittiwake

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The Black-legged Kittiwake (Rissa tridactyla) is a seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

 species in the gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

 family Laridae.

This species was first described by Linnaeus
Carolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...

 in his Systema naturae in 1758 as Larus tridactylus.

In North America, this species is known as the Black-legged Kittiwake to differentiate it from the Red-legged Kittiwake
Red-legged Kittiwake
The Red-legged Kittiwake is a seabird species in the gull family Laridae. It breeds in the Pribilof, Bogoslof and Buldir islands of the USA, and the Commander Islands, Russia. Adults are long, with an wingspan and a body mass of ....

, but in Europe, where it is the only member of the genus, it is often known just as Kittiwake.

The adults is 37–41 cm (14.6–16.1 in) in length with a wingspan of 91 – and a body mass of 305–525 g (10.8–18.5 oz). It has a white head and body, grey back, grey wings tipped solid black, and have black legs and a yellow bill. Occasional individuals have pinky-grey to reddish legs, inviting confusion with Red-legged Kittiwake. In winter, this species acquires a dark grey smudge behind the eye and a grey hind-neck collar. The name is derived from its call, a shrill 'kittee-wa-aaake, kitte-wa-aaake'.

It is a coastal breeding bird around the north Pacific and north Atlantic oceans, found most commonly in North America and Europe. It breeds in large colonies on cliffs and is very noisy on the breeding ground. Cliff nesting for gulls occurs only in the Rissa species, and the Kittiwake is capable of utilizing the very sheerest of vertical cliffs, as is evident in their nesting sites on Staple Island
Staple Island
Staple Island is a small rocky island that is one of the outer Farne Islands in Northumberland, England. Staple iIsland is known for its prolific breeding colonies of Atlantic Puffins, Razorbills and Kittiwakes. This uninhabited island has a history associated with the early monastic settlement...

 in the outer Farne Islands
Farne Islands
The Farne Islands are a group of islands off the coast of Northumberland, England. There are between 15 and 20 or more islands depending on the state of the tide. They are scattered about 2.5–7.5 km distant from the mainland, divided into two groups, the Inner Group and the Outer Group...

 (Hogan, 2005). One to two buff spotted eggs are laid in the nest lined with moss or seaweed. The downy young of Kittiwakes are white, since they have no need of camouflage from predators, and do not wander from the nest like Larus
Larus
Larus is a large genus of gulls with worldwide distribution . Many of its species are abundant and well-known birds in their ranges...

gulls for obvious safety reasons.

At fledging, the juveniles differ from the adults in having a black 'W' band across the length of the wings and whiter secondary and primary feathers behind the black 'W', a black hind-neck collar and a black terminal band on the tail. The old fisherman's name of "tarrock" for juvenile Kittiwakes is still occasionally used.

They are fish feeders, and are more pelagic than Larus gulls outside the breeding season. They do not scavenge at tips like some other gull species.

There are two races of Black-legged Kittiwake:
  • Rissa tridactyla tridactyla in the North Atlantic Ocean, which is unique among the Laridae in having only a very small or even no hind toe.
  • Rissa tridactyla pollicaris in the North Pacific Ocean, which (as the name pollex, thumb, suggests) has a normally developed hind toe.

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