Competition affects risk-sensitivity in foraging shrews

Summary Studies of risk-sensitive foraging have so far focused only on the effect of food demand on choice of feeding site. We suggest that competition is likely to be another factor influencing risksensitivity. A choice experiment with common shrews showed that, in the absence of competition, risk-aversion increased with increasing food intake relative to requirement. When apparent competitors were present, however, shrews were risk-indifferent regardless of their estimated requirement. The switch to risk-indifference in the presence of competitors appears to be an all-or-nothing rule of thumb which is not modified by experience with reward probability distributions.