Great black-backed gulls (Larus marinus) nest on islets out at sea, further away from the mainland than other gulls. Helsinki’s breeding population consists of only a few dozen pairs. In the winter, great black-backed gulls turn up at harbours and marketplaces in search of food, unlike lesser black-backed gulls.
The great black-backed gull does not reach maturity until the age of three or four, and you can often see young gulls that are still too young to breed here and there in the inner bays of Helsinki. The great black-backed gull is a predatory bird, preying on the chicks of eiders and other waterfowl, in addition to feeding on various types of waste at rubbish dumps. It is also known to follow fishing goosanders and fishermen in the hopes of snatching their catches. A pair of great black-backed gulls is known to have nested on the outermost tip of Harakka island.