Abstract # 132:

Scheduled for Sunday, September 14, 2014 04:30 PM-04:45 PM: Session 20 (Henry Oliver) Oral Presentation


FOOD-ASSOCIATED CALLING BEHAVIOR IN THE GOMBE CHIMPANZEES: MANAGING THE TRADE-OFF BETWEEN FOOD AND FRIENDS

L. R. O'Bryan and M. L. Wilson
University of Minnesota, 100 Ecology , 1987 Upper Buford Circle, St Paul, MN 55108, USA
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     Chimpanzees (Pan troglodytes) produce food-associated “rough-grunts” when feeding on high-quality food and when in the presence of preferred social partners. While there is evidence that these vocalizations can inform party members of discovered food, why signalers should attract potential competitors remains unclear. We hypothesize that, by promoting co-feeding, food-associated calling behavior may reduce the trade-off between feeding and maintaining cohesion with preferred partners. We tested this hypothesis by conducting an observational study of 10 adult male wild chimpanzees at Gombe National Park, Tanzania from January-June 2012 and 2013. During 8-hour focal individual follows, all occurrences of feeding were recorded, including the duration, the target’s vocal behavior, and the arrival of co-feeders. In addition, group composition scans were conducted every 15 minutes. Using mixed-effects regression models to control for repeated sampling of targets, feeding bouts and focal follows, we examined the correlation between rough-grunt production, feeding duration, co-feeding and group cohesion. We found that feeding duration was negatively correlated (p<.05), and co-feeding was positively correlated (p<.001), with the target’s likelihood of maintaining cohesion with party members. Also, rough-grunt production was positively correlated with both the target’s feeding duration (p<.01) and the arrival of co-feeders (p<.001). Results suggest there is a trade-off between prolonged feeding and maintaining group cohesion but, by attracting co-feeders to preferred food patches, food-associated calling may be capable of reducing this trade-off.