Seasonal surplus killing as hunting strategy of the weasel Mustela nivalis - test of a hypothesis

This paper questions the common explanation of surplus killing by small mustelids as an incidental response to superabundance of prey. Alternatively, we propose that surplus hunting in weasels is a regular seasonal (winter) strategy, a mean of: (1) balancing the cold-inducted increase of energy need, (2) compensating the concurrent restriction in hunting activity, (3) constantly supplying a "buffer" cache against unpredictable winter conditions. We tested this prediction in seminatural conditions in nineteen experiments performed over three years with 8 nonreproductive weasels Mustela nivalis Linnaeus, 1766 and very high densities of rodents, mainly the bank voles Clethrionomys glareolus (Schreber, 1780). Each experiment lasted from 6 to 25 days.