Impact of the American mink, Neovison vison, on small rodents inhabiting riparian forests along the headstream of Kushiro River in eastern

Abstract

The feral American mink’s predation on small rodents and competition with other predators have been a concern. In some foreign countries, small native rodents have decreased in population under predation pressures from alien American minks, and the vegetation around the mink’s habitats has changed drastically. Influence of the American mink on small native rodents was studied by examining the habitat conditions and seasonal change of prey, and the distribution patterns of small rodents sharing the habitat with the American mink. American minks were caught on camera traps night and day, most frequently around noon. Signs of the American mink were observed around the confluence of Kushiro River. In their dung, small rodents’ hair and bones were detected. A number of small rodents were captured where the understorey is abundant, especially on sasa-type forest floors. We assumed that the American mink can adapt themselves to the environment in which they are highly populated and thus apply high predation pressures on small rodents.