The Great Black-backed Gull, Larus marinus, is a very large gull which breeds on the European and North American coasts and islands of the North Atlantic. It is fairly sedentary, but some Great Black-backed Gulls move further south or inland to large lakes or reservoirs.
This is the largest gull, much bigger than a Herring Gull. It is 61-74 cm long with a 1.4 to 1.7 m wingspan. It is bulky, and has a powerful bill. The adults have black wings and back, with conspicuous white "mirrors" at the wing tips. The legs are pinkish, and the bill yellow with a red spot.
Young birds have scaly black-brown upperparts, and a neat wing pattern. They take at least four years to reach maturity, development in this species being somewhat slower than that of other large gulls. The call is a deep "laughing" cry.
These are omnivores like most Larus gulls, and they will scavenge as well as seeking suitable small prey. They frequently rob other seabirds of their catch. It can swallow a puffin or a small wild duck whole.