RISK OF PREDATION AND FORAGING ACTIVITY IN SHREWS

The responses of foraging common shrews Sorex araneus to the presence of a potential predator, the weasel Mustela nivalis, was studied on an experimental arena. The weasel was allowed to visit an enclosed part of the arena at will. A significant short-term (5 to 15 min) decrease of activity was observed after a visit by the weasel during both low and high level weasel activity. Individual variation in the shrews' responses was great. Some individuals decreased their foraging activity to a very low level following the weasel's visits while others did not show any change in activity at all. The magnitude of the shrew's response was positively correlated with its weight at the beginning of the experiment. The results demonstrate that, under risk of predation, large individuals could afford to decrease their foraging activity at the cost of weight loss but smaller individuals, with smaller body energy reserves, apparently could not do so.Peer reviewe