Black-legged Kittiwake
Rissa tridactyla
Small oceanic gull. Adults have solid black wingtips that look like they were dipped in ink. Also note translucent flight feathers, entirely yellow bill, and black legs. Nonbreeding birds have a dark ear patch and smudgy gray on the back of the neck. Immatures are boldly patterned with a black collar and “M” pattern on wings. Rather buoyant in flight, sometimes soaring in high arcs in windy conditions. Breeds at high latitudes across the Northern Hemisphere, primarily in large colonies on cliffs and other structures overhanging water. Spends the winter on the open ocean, sometimes seen from shore. Rare inland. Can gather in flocks during migration and winter, especially where food is abundant.
Identification
The adult is 37–41 cm (15–16 in) in length with a wingspan of 91–105 cm (36–41 in) 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, black legs and a yellow bill. Occasional individuals have pinky-grey to reddish legs, inviting confusion with red-legged kittiwake. The inside of their mouth is also a characteristic feature of the species due to its rich red colour. Such red pigmentation is due to carotenoids pigments and vitamin A which have to be acquired through their diet. Studies show that integument coloration is associated with male's reproductive success. Such hypothesis would explain the behavior of couples greeting each other by opening their mouth and flashing their bright mouth it to their partner while vocalizing. As their Latin name suggests, they only possess three toes since their hind toe is either extremely reduced or completely absent. The two subspecies being almost identical, R. tridactyla pollicaris is in general slightly larger than its counterpart R. tridactyle tridactyla. In winter, this species acquires a dark grey smudge behind the eye and a grey hind-neck collar. The bill also turns a dusky-olive color.<p>Since kittiwakes winter at sea and rarely touch ground during this period, very little is known about their exact molting pattern.<p>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. They can also be identified due to their solid black bill. This plumage is a hatch-year plumage and will only remain for their first year. Kittiwakes obtain their mature plumage at 4 years old, but will gradually change their juvenile plumage over time until maturity is reached. A second-year juvenile resembles a hatch-year regarding the plumage, though the bill is no longer solid black but instead has a greenish color. The black marking on the coverts and the tail is still visible. The black marking will only molt during their third year, where the black is no longer present on the coverts, but the grey smudge on the head remains. A third-year bird will also exhibit a small zone of bright yellow/orange at the base of its mostly greenish bill. It is only at four years old that the bill will reach an overall colour of bright yellow and complete its mature plumage.<p>The old fisherman's name of "tarrock" for juvenile kittiwakes is still occasionally used.<p>The red-legged kittiwake is the only other species in the Rissa genus and can be differentiated from its counterpart by its red legs, as the name suggests. The head of the red-legged kittiwake is slightly smaller and bears a shorter bill. The chicks of the Pacific black-legged kittiwake and red-legged kittiwake cannot be distinguished during their youngest downy phase.<p>The juvenile black-legged kittiwake can be confused with the Bonaparte's gull juveniles although the kittiwakes' plumage has more black on the primaries and a different pattern going across the coverts.
Taxonomy
Genus: Rissa; Family: Laridae; Order: Charadriiformes.
- Scientific name
- Rissa tridactyla
- Authority
- (Linnaeus, 1758)
- Order
- Charadriiformes
- Family
- Laridae
- Genus
- Rissa
Range and habitat
Breeding range: PAL, NA : high Arctic to temperate n coasts, from Greenland, Iceland, w, nw Europe, Svalbard (n of Norway), n Siberian is. to Sakhalin, Kamchatka, Kuril and Commander is. (e Russia); Aleutian and Bering Sea is., w, sw Alaska mainland; Canadian high Arctic (ne Canada), Gulf of St. Lawrence and Newfoundland (se Canada). Non-breeding range: w North Atlantic coast and coastal waters s to Virginia; mid-Atlantic Ridge to Azores; North Sea; Japan, Korean Pen., se Alaska to s California (USA).
- Breeding range
- PAL, NA : high Arctic to temperate n coasts, from Greenland, Iceland, w, nw Europe, Svalbard (n of Norway), n Siberian is. to Sakhalin, Kamchatka, Kuril and Commander is. (e Russia); Aleutian and Bering Sea is., w, sw Alaska mainland; Canadian high Arctic (ne Canada), Gulf of St. Lawrence and Newfoundland (se Canada)
- Non-breeding range
- w North Atlantic coast and coastal waters s to Virginia; mid-Atlantic Ridge to Azores; North Sea; Japan, Korean Pen., se Alaska to s California (USA)
- Migration
- Complete migrants
Behavior
Migration pattern: Complete migrants.
Conservation
Population trend: declining.
- Population trend
- declining
Photos
Distribution
Bird Calls
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