Food Requirement and Risk-Sensitive Foraging in Shortfall Minimizers

Risk-sensitive foraging, generally characterized as the response of predators to variance in food reward (see Stephens and Krebs 1986) in choosing where and what to eat, is now well-established both in theory and empirically (see Stephens and Krebs 1986, Real and Caraco 1986 for recent reviews). While foraging models incorporating risk-sensitivity have been applied to a number of foraging situations (Real and Caraco 1986), the commonest scenario involves a high energy demand predator which risks starvation if there is a shortfall in its food supply. If such a predator makes foraging decisions so as to minimize the probability of a shortfall, reward variance is likely to be an important criterion on which decisions are based (e.g. Caraco 1981, Stephens 1981, McNamara and Houston 1982, Stephens and Paton 1984). In this paper, I look at some of the circumstances in which shortfalls and risk-sensitive choices might be expected, and at the evidence that such choices are made by predators. I also look at the effect of risk-sensitivity in foraging on decisions in other life history contexts.