Breeding Arctic Terns Kill Lemmings

Abstract

Arctic terns (Sterna paradisaea) are well known for exhibiting vigorous defense of nests at their breeding colonies. However, in 2008 we observed a previously unreported behavior by terns. We watched chick-rearing adult terns attacking collared lemmings (Dicrostonyx groenlandicus), which included repeatedly lifting them into the air and dropping them to the tundra until they died. Terns attack certain birds and mammals that intrude on their breeding territory but do not attack other species that are known to depredate eggs, suggesting that the ability of terns to discriminate threats is imperfect.