Abstract # 136:

Scheduled for Sunday, September 18, 2011 10:45 AM-11:00 AM: Session 18 (Meeting Room 410) Oral Presentation


THE EFFECT OF FOOD-ASSOCIATED CALL PLAYBACKS ON THE FEEDING SITE CHOICES OF CAPTIVE CHIMPANZEES (PAN TROGLODYTES)

L. R. O'Bryan1, M. L. Wilson1, S. P. Lambeth2 and S. J. Schapiro2
1University of Minnesota, 100 Ecology Building, 1987 Upper Buford Circle, St Paul, MN 55108, USA, 2Michale E. Keeling Center for Comparative Medicine and Research, The University of Texas M. D. Anderson Cancer Center, Bastrop, Texas 78602, USA
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     Though multiple studies have investigated the proximate basis for chimpanzee food-associated “rough-grunt” production, this call’s function remains unclear. Three hypotheses for the function of food-associated calls are: 1) they increase the proximity, 2) decrease the proximity, or 3) coordinate the foraging behavior of listeners. Hypotheses 1 and 3 predict the attraction of listeners while hypothesis 2 predicts their repulsion. We conducted a playback experiment with captive chimpanzees (n=12) at the Keeling Center, TX to evaluate these predictions. Subjects were trained to expect one “food patch” (room containing 60 grapes) on either side of a holding room. Each subject then experienced two stimulus trials and one silent trial to test for side preferences. During stimulus trials, a rough-grunt or control call was broadcast from one patch before releasing the subject. Control calls consisted of pant-hoots, pant-grunts, or human-directed vocalizations. We found no significant side preferences during silent trials, with 8 of 12 subjects (chi-squared, p=.25) approaching the right room first. However, significantly more subjects than expected by chance (10 of 12, chi-squared, p=.02) approached the stimulus room first in rough-grunt, but not control call (7 of 12, chi-squared, p=.56) trials. Results support the prediction that rough-grunts promote attractive rather than aversive behavior and suggest that rough-grunts are more attractive than other species-specific vocalizations. Work is in progress to differentiate between the increased proximity and coordination hypotheses.