The Great black backed gull (Gull marinus), also known as the greater black-backed gull or, informally, as the black-back, is slightly smaller than a herring gull. It is distinguished by its sheer size and unmistakable black back and wings. Adults are blacker than the smaller lesser black-backed gull. The bill is yellow with a red spot, like the Lesser Black-backed Gull and Herring Gull. The eye is yellow with a red orbital ring. The legs and feet are pink; these facts together with the size of the bird are distinguishing features. In the winter the head is lightly streaked with grey.