Sg. Kohlmann et Kl. Risenhoover, EFFECTS OF RESOURCE DISTRIBUTION, PATCH SPACING, AND PREHARVEST INFORMATION ON FORAGING DECISIONS OF NORTHERN BOBWHITES, Behavioral ecology, 9(2), 1998, pp. 177-186
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.