Time to revisit? A predator's previous successes and failures in prey capture determine its return time to patches.

ABSTRACT

In a heterogeneous environment containing multiple patches that may deplete and renew, a forager should be able to detect the quality of food resources within and among patches and choose to exploit them to best maximize returns. From the predator's perspective, the behavioral responses of the prey in a patch will be perceived as depletion when they retreat to refuge and renewal when they reemerge. A predator encountering responsive prey should manage predation risk, and thus behavioral resource depression, by optimally timing its return time to the patch based on prey behavior. We evaluated the foraging decisions of a predator that encountered patches differing in size of the refuge and prey density. We used little egrets and goldfish as predators and prey in an environment that contained three patches (pools). We manipulated prey density and refuge size and availability (using covers) and observed predator foraging behavior. When the egret had previously caught a fish it did not discriminate between the pools, and the return time was similar for all cover types. The fish densities also did not affect the egret decisions to return to pools. However, when it failed to catch fish, it returned sooner to the pool containing the small cover than the larger one. Additionally, after failing to catch fish in patches containing the highest prey density, the egrets subsequently preferred to return to such patches sooner. We show experimentally that previous failures influence the foraging decisions of a predator choosing how quickly to return to a previously visited patch.