A Great Black-backed Gull lands on a sign in a marina that reads 'Danger.'

Black-headed gull (Chroicocephalus ridibundus) in winter plumage in this popular coastal town, Aberaeron, Ceredigion, Wales, United Kingdom, Europe

A chick of a Great Black-backed Gull (Larus marinus), on Staple Island, Farne Islands, Northumberland, England, United Kingdom, Europe

Cormorant birds and Black Backed Gull in Courtmacsharry Bay, County Cork, Ireland

Greater Black-Backed Gull by San Francisco bay, California, United States of America

Greater Black-Backed Gull by San Francisco bay, California, United States of America

Greater Black-Backed Gull by San Francisco bay, California, United States of America

Black-backed gull (larus dominicus) Brown Bluff, Antarctica, Southern Ocean.

Lesser black backed gulls nesting on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

Juvenile Great black-backed gull (Larus marinus) in flight, UK

A lesser black backed gull chick at Europes largest Gull Colony of Herring and Lesser Black Backed Gulls on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

A Lesser Black Backed Gull attacking an intruder near its nest on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

Lesser black backed gulls nesting on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

Great black-backed gull (Larus marinus) and shag (Phalacrocorax aristotelis) sharing a rock. Hebrides, Scotland.

A lesser black backed gull chick nesting on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

Lesser black backed gulls nesting on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

Juvenile Great black-backed gull (Larus marinus) in flight, UK

A lesser black backed gull's nest on Walney Island near Barrow in Funress, Cumbria, England, United Kingdom, Europe

White-tailed Eagle or Sea eagle (Haliaeetus albicilla) in flight with prey, and Great Black-backed Gull (Larus marinus) behind, Flatanger, Nordtrondelag, Norway, Scandinavia, Europe

White-tailed Eagle or Sea eagle (Haliaeetus albicilla) in flight with prey, badgered by a Great Black-backed Gull (Larus marinus) behind, Flatanger, Nordtrondelag, Norway, Scandinavia, Europe

Lesser black backed gull, Isle of May, Scotland, UK,

Great Black-backed Gulls with a comb in the beak, France

Lesser black-backed gull (Larus fuscus) young chicks, Farne Islands, Northumberland, UK