Black Terns breed in colonies in lakes, marshes and wetlands characterized by shallow water and floating vegetation. During the last century, the number of Black Terns has dropped off in Sweden and in other countries in Western and Central Europe. Because it is considered a threatened species, the Black Tern is listed in EU's Birds Directive. The population of Black Terns in Sweden is about 200 pairs and about one third of the population breed in the province of Västmanland, where Asköviken is an important locality.

Photo: Anders Geidemark