Lesser black-backed gulls (Larus fuscus) are the only long-distance migrant gulls found in Finland, spending their winters in equatorial Africa. They migrate away as early as September, and do not return until April. The lesser black-backed gull is classified as critically endangered in Finland. The species is susceptible to environmental toxins, which it accumulates during migrations.
The numbers of lesser black-backed gulls nesting in Helsinki have recovered in recent years, unlike in other areas in Finland. The breeding population found on Harakka island consists of a few pairs of gulls. The largest colonies of several dozen pairs can be found on the islets along the ferry route to Suomenlinna. As the name implies, the lesser black-backed gull has a black back and is smaller than the great black-backed gull. Its feet are yellow.