Balancing variable patch quality with predation risk.

Patch choice is almost always under the influence of multiple factors. Patch quality and the threat of predation are two such factors that have been shown to influence the foraging decisions of animals. In addition, aspects of patch quality may also vary with time, and consequently animals should incorporate temporal information to reduce their uncertainty about current patch conditions. The temporal weighting rule (TWR), which has been validated in previous studies, describes how animals should choose among variable options with the passage of time. In this study, we varied an additional factor, predation risk, along with certainty about patch yields in a field experiment, utilizing individually marked, free-ranging least chipmunks, Tamias minimus. We gave the animals in each condition experience at our experimental patches and then recorded patch choices a few minutes or one to 2 days later. The results show that animals combined perceived predation risk with a progressively shifting assessment of patch quality to form estimates of overall patch value as modeled by TWR. Based on the information available, the animals' patch choices were, arguably, the most adaptive choices.