The ecology of weasels (Mustela nivalis) on mixed farmland in southern England

As part of a programme of research into the effects of cereal farming on wildlife, we investigated habitat use by weasels (Mustela nivalis) on mixed farmland. Three female and seven male weasels were radio-tracked. Weasels on arable land were exclusively diurnally active, perhaps in response to higher predation risk at night. Females and sub-adult male weasels had smaller ranges than did adult males, but all ranges were unusually large, probably as a result of low prey densities. Weasels rarely traveled more than 5 m from linear habitats, which were composed mainly of woodland edge and hedge with ditch. These habitats were relatively rich in small mammals. Heavier males had lower densities of linear habitats in their ranges than did lighter males, but larger absolute amounts of woodland edge. The proportion of linear habitat used by male weasels decreased with an increase in percentage and density of woodland edge available within their range. In contrast to females, males rarely entered the woodland. Differences between males and females in habitat use may be due to differences in their size-related ability to exploit small rodent prey.