The Optimal Patch Use in Divers: Optimal Time Budget and the Number of Dive Cycles During Bout

Diving animals feeding on patchily distributed prey repeat dives with short surface intervals. For optimal foraging, they must optimally organize both the time budget and the number of dive cycles at a given patch. The cost of time and energy consumption per dive cycle is strongly affected by the respiratory metabolism used during dive because energetically efficient aerobic diving allows only a brief foraging duration during a dive whereas inefficient anaerobic diving allows a long foraging duration. I develop a model that predicts the effects of prey patch type on the optimal combination of time budget and the number of dive cycles by using the “marginal value theorem”. General features of the results are: (1) using anaerobic metabolism increases the range of prey patch types worth using in the habitat. (2) Anaerobic metabolism is favorable when the prey patch quality is high, the prey patch is situated in deep water, and the prey patch is hard to find, although the last one is not a strong condition. (3) When only aerobic diving is favorable, the time budget of the dive cycle is little affected by patch quality, but when anaerobic diving is favorable, it is strongly affected by patch quality. It is affected by patch depth in both cases. (4) When a dive bout is composed of many dive cycles, the dive duration and surface interval of the dive cycle are short. When long dive duration with long surface interval is optimal, the optimal number of dive cycles during the bout is small.