Abstract # 2861 Event # 123:

Scheduled for Saturday, June 19, 2010 09:00 AM-09:10 AM: Session 20 (Medallion Ballroom B) Oral Presentation


PAN HANDLING TIME: OPTIMIZATION IN THE RECOVERY OF HIDDEN FOODS BY CHIMPANZEES (PAN TROGLODYTES), AFTER LONG DELAYS

K. Sayers and C. R. Menzel
Georgia State University, Language Research Center, Decatur, GA 30034, USA
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Contingency models of diet choice assume that feeding decisions are made at the time resources are encountered. Some primates, however, may possess knowledge of foods located outside the range of perception. Little is known about what food characteristics are retained in long-term memory, or how this information relates to foraging efficiency. To investigate these issues, we sequentially presented two chimpanzees (Panzee and Sherman, n=20 trials apiece) with ten transparent bags of almonds per trial, each varying in quantity (kilocalories) and shell presence/absence (high/low processing time). The bags were hidden under forest cover outside the subjects’ outdoor enclosure. After delays ≥15 minutes, subjects interacted with a person naïve to locations or contents of hidden bags. The chimpanzees directed the uninformed persons to hidden bags one by one via manual pointing and other gesture. There was a strong, significant negative correlation between recovery order and profitability (kcal/handling time) of each bag, consistent with optimization under instantaneous rate maximization [Pearson r: α=0.01]. The order in which bags were recovered was related to both quantity and shell presence/absence. The two subjects weighted these variables differently in selecting recovery order, as predicted by individual-specific almond processing times. These results suggest that differing heuristics can result in equally efficient solutions, and that cognitive factors hold promise for incorporation into foraging models. Supported by HD-38051, HD-056352, 1F32HD061177.