Any of the two seabird species of genus Rissa from Laridae family are kittiwakes. They are closely related to gulls, which also belong to the family Laridae. The two species of kittiwakes which are includes in genus Rissa are given below:
- Black-legged Kittiwake (R. tridactyla)
- Red-legged Kittiwake (R. brevirostris)
These two species are found it North America. But, in Europe only black-legged kittiwakes are found. So they are called as black-legged kittiwakes or just kittiwakes in Europe. They are also called as Tickleass or Tickleace in some areas. They get the name because of their sound of calling 'kittee-wa-aaake, kitte-wa-aaake'.
Kittiwakes inhabit in Arctic, North Pacific, and North Atlantic oceans. These are colonial birds, which creates large colonies in their reproductive summer season. They nests on cliff. In fact they are the only gull species which nests totally on cliffs. Kittiwakes are coastal breeders. They often share their living place with murres.
Black-legged kittiwakes are found in large numbers as compared to the red-legged kittiwakes. The breeding colonies of black-legged kittiwakes are found in the Pacific ocean Kuril Islands, Sea of Okhotsk, Bering Sea, Aleutian Islands to the southeast Alaska. However in Atlantic Ocean, they are found in Gulf of St. Lawrence, Greenland, Great Britain to Portugal as well as in the Arctic islands. During winters, they move towards the south. On the other hand, the red-legged kittiwakes breeds on the Bogoslof, Pribilof, and Buldir islands of USA, and the Commander Islands in Russia.
Both the species are very similar in appearance. Kittiwakes have white color on body and head. They have grey back and grey wings with solid black tip. Color of their bill is yellow. However the differences are like, the black-legged kittiwakes are larger than the red-legged kittiwakes. Black-legged kittiwakes have 40 cm length and 90-100 cm wingspan. Meanwhile red-legged kittiwakes have 35-40 cm length and 84-90 cm wingspan.
The other differences between the two species appearance include short bill, large eyes, a large head and dark grey wings in red-legged kittiwake and dark-grey legs or pinkish-grey to reddish legs in black-legged kittiwakes. The male and female bird looks same. A young bird takes three years to reach maturity.