| Abstract: | Food-choice was investigated in a social group of 16 chimpanzees (Pan troglodytes) maintained in a large outdoor compound. Three feeding stations located along the periphery of the compound were considered analogous to food patches. Color-coded aluminum panels temporarily covered each feeding apparatus, with one color corresponding to nonpreferred food (commercial biscuits) available at two locations and other colors corresponding to the certain or uncertain availability of preferred food (oranges) available at one location. Only nine chimpanzees met the criterion for learning the color/food associations and thus only those animals were included in the analysis. There was a significant decrease in choosing the station associated with oranges when the probability of availability of oranges was reduced from 0.5 to 0.1 but not from 1.0 to 0.5. In addition, there was a significant increase in the frequency with which the subjects made no choice when the probability of availability of oranges was reduced from 1.0 to 0.1. The data indicate that the uncertain availability of preferred food in a choice situation affects choice behavior in a social group of chimpanzees studied under controlled conditions. |
