Uso de pedras como ferramentas para obtenção de alimentos por macacos-prego selvagens (Sapajus libidinosus)

Abstract

Wild capuchin monkeys use stones tools to access food items that otherwise would be unavailable, as encapsulated fruits and seeds. The successful completion of this activity not only requires the selection of the suitable tool, but also the correct technique. In order to analyze if the stone tools used by the capuchin monkeys are adjusted to the type of food item consumed and if this adjustment entails variations or behavioral adaptations to accomplish the task, stone tools and techniques used by animals to process five distinct food items, were compared. The study was conducted in an area of Pernambuco’s semiarid Caatinga, located in Serra Talhada. Along 15 months, 257 sites were identified, characterized and monitored. Behaviors of using stones as tools were documented by camera traps. Accounted a ‘total of 395 stones, used as hammers to break of five food items: Syagrus oleracea, Manihot epruinosa, Pilosocereus pachycladus, Tacinga inamoena and Commiphora leptophloeos, these last three were not yet described as accessed auxiliary items by other populations of capuchin monkeys. The use of stones as tools to process the cactaceae revealed especially interested, such strategy is related to the presence of these item’s thorns. It was found also that the characteristics of food items such as hardness, size and the presence of spines influences the stone’s selection to be used as hammers. The postures adopted by the animals for activity breaks are similar to those already described in other studies, however behavioral adaptations in handling the tool are performed to increase its functionality.