Supply-Side Optimization: Maximizing Absorptive Rates

The complexities of feeding behavior extend far beyond the simple priorities of life in The Hundred Acre Wood. Vermeij (1987), for example, has suggested that predator-prey relations have continually escalated as predators and prey co-evolved. A consequence of such escalation is that prey defences and predator weapons against them both continue to become more effective. The ultimate source of the material and energy for this escalation in heterotrophs with digestive tracts is absorption across the gut wall. Thus it is arguable that the lowest common denominator in foraging theory should be absorption of digestive products; the ultimate evolutionary escalation must be in rate of gain from food. Most foraging theory, however, focuses on choice of diet and feeding location (Stephens and Krebs, 1986) and stops with prey acquisition and pre-ingestive handling — despite the fact that digestive handling times often far exceed pursuit and ingestive handling times.