Proximity, Contact, and Play Interactions of Zoo-Living Juvenile and Adult Orangutans, with Focus on the Adult Male

Abstract

The behavioral development of young apes is influenced by their physical and social environments. Deficient or limited environments can result in reproductive insufficiencies (see Beck and Power, 1988) and behavioral deficits, such as Stereotypic movements (see Puleo, et al., 1983; Meder, 1989). The role of the environment in behavioral deficits is evident from studies where stereotypies were reduced or eliminated when the physical or social environments were enhanced (Clarke, et al., 1982; Puleo, et al., 1983; Meder, 1989). The mere presence of conspecifics, however, does not guarantee the development of species-typical behavior, even in complex social groups. For example, a young orangutan reared in a social group containing only adults is limited in its opportunities for social play (Zucker, et al., 1986; see Baldwin, 1986, for more about social and ecological constraints on play). Although adult orangutans of both sexes do play, the rate of adult play is much lower than that of immature orangutans (Zucker, et al., 1986), and in playing with immature orangutans, the style of play of adult females differs from that of adult males (Zucker, et al., 1978). Nursery-reared apes are at risk for behavioral deficits as their social and physical environments usually are less complex than their respective natural environments, although nursery environments and rearing protocols can be made relatively complex and stimulating.