Experimental study of tool use to nutcraking by semifree ranging capuchin monkeys (Cebus apella)

Author(s)

Tiago Falótico

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Psicologia (IP/SBD)
• Defense date: 2006-05-11

Examining board members

Eduardo Benedicto Ottoni; Dorothy Fragaszy; Francisco Dyonisio Cardoso Mendes

• Advisor: Eduardo Benedicto Ottoni
• Field of knowledge: Humanities - Psychology
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP; Index Psi Teses - IP/USP
• Location: Universidade de São Paulo. Biblioteca do Instituto de Psicologia; QL737.P925; F196e

Abstract

Three experiments were conducted about tool use to nutcracking by capuchin monkey (Cebus apella) at semi-free ranging condition in Tiete Ecological Park. The first involved the introduction of a new species of nut; the aim was to study the dissemination of the use of this new fruit in the group and the involved social transmission mechanism. The quite fast dissemination occurred by individual learning in some cases, but there were instances of consumption only after observation of other monkeys cracking the new nuts or contact with their leftovers.In the latter case, the possible social influences would be restricted to Stimulus Enhacement, but, in the cases where direct behavioral observation took place, Imitation and Emulation cannot be ruled out. There was no correlation between the choice of targets for observation and the measured traits of the targets. The second experiment examined the preferences in the choice of artificial stone hammers ranging from 300g to 1700g. We found a preference for the two heviest hammers, although the juveniles had a tendency to use the nearest tools, independently of weight. The third experiment was about the transport of tools, to determine if the transport of potential tools occurred when these were found at 5m or 10m from the use site (the “anvil"). The results confirms the occurrence of this behavior, always involving the simultaneous transport of nuts. (AU)