Kittiwake

The kittiwakes are two closely related seabird species in the gull family Laridae, the black-legged kittiwake (Rissa tridactyla) and the red-legged kittiwake (Rissa brevirostris). The epithets "black-legged" and "red-legged" are used to distinguish the two species in North America, but in Europe, where Rissa brevirostris is not found, the black-legged kittiwake is often known simply as kittiwake. The name is derived from its call, a shrill 'kittee-wa-aaake, kitte-wa-aaake'. The genus name Rissa is from the Icelandic name Rita for the black-legged kittiwake. The two species are physically very similar. They have a white head and body, grey back, grey wings tipped solid black and a bright yellow bill. Black-legged kittiwake adults are somewhat larger (roughly 40 cm or 16 in in length with a wingspan of 90–100 cm or 35–39 in) than red-legged kittiwakes (35–40 cm or 14–16 in in length with a wingspan around 84–90 cm or 33–35 in). Other differences include a shorter bill, larger eyes, a larger, rounder head and darker grey wings in the red-legged kittiwake. While most black-legged kittiwakes do, indeed, have dark-grey legs, some have pinkish-grey to reddish legs, making colouration a somewhat unreliable identifying marker.

Source: Wikipedia