The Biological Bulletin, Vol 193, Issue 2 171-186, Copyright © 1997 by Marine Biological Laboratory

ECOLOGY AND EVOLUTION

Nearly Optimal Foraging in Patches Under Nutrient Constraints

J. F. Boyer
Department of Biological Sciences, Union College, Schenectady, New York 12308

Three feeding strategies with different rules for prey selectivity were evaluated by Monte Carlo computer simulation. The predator must obtain a minimum quantity of each of three different nutrients, and it sequentially encounters one of three kinds of prey that differ in both their nutrient compositions and their relative abundances. Within patches, prey may be randomly dispersed or aggregated with Markovian transition probabilities. Overall cost is the sum of search time plus consumption cost plus emigration (between-patch traverses) risk. The predator will emigrate if it is unsuccessful in acquiring a minimum of {Gamma} units of any needed nutrient within the T most recent prey encounters. The three strategies are (1) no discrimination-with potentially high consumption costs, (2) minimal consumption-with potentially very prolonged search times, and (3) a hybrid strategy that requires a physiological monitoring of net nutrient acquisition (or the bookkeeping of highly correlated gustatory cues). Each strategy has its characteristic dynamics and optima, but collectively these simulations show that no one strategy is superior and that over a large portion of the parameter space the differences in overall cost are relatively small.