Black-legged Kittiwake

Rissa tridactyla (Linnaeus, 1758)

		adult
2015-09-11 Laptev Sea, 77° 57,67' N 130° 30,28' Е.	© Georgy Vinogradov

Description

Black-legged Kittiwakes is medium-sized gull, close on Common Gull in size. It is distinguished from Common Gull by the black legs and by the absence of white patches on black tips of two first (outer) primaries. The anatomic feature of Black-legged Kittiwakes is absence of rear toe. (On position of rear toe there is only little prominence. Hereof the scientific name of Black-legged Kittiwakes - tridactyla means “three-toed”.) In autumn plumage nape and hind-neck are grey, on ears there are dark-grey patches usually crescent-shaped, but very variable in size, to the point of jointing on nape. Juveniles have same dark head pattern and also black semi-ring on the hind-neck; black angle-shaped band is along whole wing. Tail have black terminal band which is broader in center than in edges, therefore tail may seems cut from far. Yearling birds (2nd calendar year) are same to juveniles but dark patterns become paler (browner) and less in size; during the summer dark replaces to light plumage; bill is dark-yellow dark-tipped. Weight 300-530 gr, length 38-46, wing 29.7-33.0, wingspan 106-125 cm.

References

В.К.Рябицев. "Птицы Сибири". Москва-Екатеринбург, Изд-во "Кабинетный ученый", 2014.