Patch choice and risk: relative competitive ability is context dependent

The relative abilities of individual cichlids, Tilapia zillii to obtain food under scramble competition was highly repeatable between trials using a single input source, regardless of whether the input was constant or variable. However, when given a choice between two patches differing only in their temporal variability in input about an identical mean, an individual's rank based on intake in one patch was uncorrelated with either its intake in the other patch or its intake in the single-patch trials. In the two-patch trials, certain individuals both spent more time in food patches and visited patches more often than others, and overall the fish spent more time in the constant rate patch than the variable patch, leading to more items being consumed from the constant rate patch. We discuss possible causes and consequences of this dependence of relative competitive ability on the context of the foraging situation. Copyright 1999 The Association for the Study of Animal Behaviour.