Exploration and exploitation of foraging patches by desert sparrows
Submitted by Johan on 8 May 2015.Get the paper!
Food resources are generally patchily distributed which has triggered a plethora of foraging models predicting both exploration behaviours to find high-quality patches and exploitation levels when foraging in a patch.
In a series of ingenious semi-controlled field experiments, Milesi and Marone set out to test some of these predictions using a seed-eating, desert living population of rufous-collared sparrows as model organisms.
Seed density was always higher under trees and in areas where litter had accumulated and birds used this information to start to forage in such areas. The clever experimental set-up made it possible for Milesi and Marone to separate the cue; tree cover and litter, from the actual density of seeds by removing seeds from the litter and creating high seed density patches on bare soil. It turned out that the sparrows explored their immediate surroundings to an extent that made it possible for them to quickly detect the high-density seed patches even if they occurred on bare soil and subsequently, preferentially used these areas for foraging. Thus, the sparrows used reliable cues for starting a foraging bout but also sampled the environment thoroughly enough to find sporadic rich patches.
Jan-Åke Nilsson, Editor in Chief
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