Abstract # 121:

Scheduled for Saturday, August 26, 2017 05:00 PM-05:15 PM: (National Ballroom Salon A) Oral Presentation


TOOL USE BY YOUNG ADULT BEARDED CAPUCHIN MONKEYS (SAPAJUS LIBIDINOSUS): DOES AGE OR BODY MASS PREDICT PROFICIENCY?

N. Aiempichitkijkarn1, J. Parrilli1, J. C. Respress1, P. Izar2 and D. M. Fragaszy1
1University of Georgia, Department of Psychology, Athens, Georgia 30605, USA, 2 Department of Experimental Psychology, University of Sao Paulo, SP, Sao Paulo, CEP 05508-030, Brazil
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     Bearded capuchin monkeys at Fazenda Boa Vista, Brazil, begin to crack whole piaçava palm nuts using stone hammers after they reach about 1.5 kg body mass. The monkeys gain body mass until 8 - 10 years old, with females averaging 2.1 kg and males 3.5 kg. Does age or body size predict success or efficiency at cracking nuts? We videotaped five monkeys (4.3 - 8.4 years old; 3 females; body mass 1.7 - 2.5 kg) as we provided them with 14-35 piaçava nuts per individual. We coded actions with each nut, and the outcome. Monkeys attempted to crack 96 nuts (range: 14-27). Four capuchins cracked the nut on > 75% of their attempts, using 11 strikes per nut on average (range 5.3 - 17.6), overlapping the range of older adults studied previously. The fifth capuchin never cracked a nut, although she attempted to do so. This monkey sniffed and tapped nuts at higher rates than the others (p<.001 and 0.018, respectively), indicating continued interest. Body mass and age were modestly negatively correlated with percentage of nuts cracked and average number of strikes to crack a nut (rs = -.32 to -.40, N = 4 or 5, NS). We conclude that proficiency does not parallel age nor body mass, and individual timelines to develop cracking vary widely. Permission by IBAMA #28689 and by CNPq/MCT #0002547/2011.