Intra-and Inter-Specific Social Learning of a Novel Food Task in Two Species of Tamarin

Abstract

Intra-and inter-specific social learning was investigated in two species of New World monkey, the saddle-backed tamarin {Saguinus fuscicoUis) and the redbellied tamarin {S. labiatus), which form stable and permanent mixed-species troops in the wild. We explored whether improved food acquisition, through social learning, is a potential advantage of mixed-species troop formation by allowing a pair of naive observers to watch a pair of trained demonstrators complete a novel foraging task. The aims of the study were (a) to determine if individuals succeeded at the task more quickly after having observed demonstrators, (b) to investigate whether speed of acquisition differed after observation of conspecific demonstrators as opposed to congeneric demonstrators, and (c) to compare performance between species. The number of trials taken by observers to succeed on the task was compared with that taken by naive demonstrators to succeed on the task initially. Individuals succeeded on the task more quickly if they had had the opportunity to watch demonstrators perform the task, regardless of whether the demonstrator was a conspecific or congeneric. There was no difference in performance between species. It is concluded that, for both species, the learning of a new foraging technique is facilitated by the presence of both conspecifics and congenerics and that the likely mechanism for this facilitation is a combination of stimulus enhancement and response facilitation. Social learning of this kind is discussed with respect its adaptive value in wild mixed-species tamarin troops.Tamarins of the genus Saguinus are small bodied (300-550g: Hershkovitz, 1977), diurnal, arboreal, South American primates which feed primarily upon insects, ripe fruits, nectar, and plant exudates (Snowdon and Soini, 1988;Garber, 1993). Their social lives are characterised by high levels of co-operation, tolerance and adaptability (Caine, 1993). When travelling and foraging troop members move in a cohesive manner (e.g., Yoneda, 1984a; Goldizen, 1987 for S.