EFFECTS OF RESOURCE DISTRIBUTION, PATCH SPACING, AND PREHARVEST INFORMATION ON FORAGING DECISIONS OF NORTHERN BOBWHITES

We investigated patch assessment by northern bobwhites (Colinus virgin ianus) in an experimental arena where the distribution of resources in patches, preharvest information about these patches, and spacing of p atches varied. We found that preharvest information about patch qualit y and a bimodal distribution of patch rewards allowed birds to selecti vely exploit patches high in resources. In contrast, uniform distribut ion of patch qualities and lack of preharvest information caused birds to forage nonselectively among patches. Birds distinguished among pat ches of different quality when these patches were spaced 1.5 m apart, but failed to react to patch quality differences when patches were 0 o r 3 m apart. We also found a strong effect of the level of patch deple tion on foraging decisions: as resources in the arena became scarce, b irds increasingly foraged selectively in the most profitable patches. Foraging decisions of bobwhites are biased by the way they experience and memorize a spatially and temporally variable environment. The rela tive cost of this cognitive bias (i.e., lost opportunity) is nonlinear ly related to the mean resource density in the environment and to the difference between this mean density and the resource density in the e xploited patch. Cognitive bias should be considered when evaluating pa tch assessment capabilities of foragers in complex environments.