Effects of home-range characteristics on the diet composition of female American mink in the Baltic Sea archipelago

Abstract

Predator home-range size may serve as a proxy of resource abundance and spatial structure of home range may also reveal information about diet composition of predators. We studied the diet of American mink <em>Mustela vison</em>, an introduced predator in Europe, to explore diet composition and to examine the association of diet with home-range characteristics. We collected scats of radio-tracked mink (two males and nine females) in summers 2004-2005 in the Archipelago Sea, SW Finland. The most important prey groups were fish (33% occurrence), birds (28%) and small mammals (mainly voles; 15%). The proportion of small mammals in female mink diet correlated positively with home-range size, which indicates that larger home ranges include larger islands, where vole populations are more persistent. Our results highlight the importance of fish as main prey for survival and invasion of mink in the outer archipelago, subsidising mink impact on other prey.