| Abstract: | The behavior of 12 orangutans (three adult males, two adult females, two subadult males, three adolescent males, and two infant males) was observed on a 450-m2 island at the Singapore Zoological Gardens (SZG). Male orangutans (6–18 years old) showed less social and solitary play as they aged; adults (over 16 years old) were not seen to play. As they grew older males increasingly spent less time making physical contact, but the amount of time they spent in proximity (within arm's length) to others increased. Adult females regularly played with other group members. Contact, allogrooming, and social play showed nonrandom relationships between individuals. Adult females showed the most allogrooming and contact, adolescent and subadult males the most play. There was no obvious dominance hierarchy. One adult male spent about 10% of his time walking around the perimeter of the island. One-year-old infants rarely interacted with other individuals apart from their own and the other infant's mother. While orangutans lead relatively solitary lives in nature, it was concluded that the opportunities for social contact and play provided by the SZG orangutan island were beneficial to this species in captivity. Opportunities for social interaction provided the animals with a means of increasing the stimulus component of their environment, thus compensating for the inevitable restriction of complexity and unpredictability as compared with the wild state. |
