Play profiles of captive adult orangutans: a developmental perspective.

The social play of 6 adult orangutan heterosexual dyads was observed, and the frequencies of the component behaviors extracted. Frequencies were converted to proportions of total play outputs for each individual and for each age/sex class, and then compared to the proportions observed for the social play of juvenile and adolescent orangutans. Adult play was more stationary, and contact maintaining, in style than was the play of younger orangutans.

Cyclic proceptivity in a captive female orang-utan (Pongo Pygmaeus Abelii).

An adult male-female pair of orang-utans was observed for a 3-month period, commencing with the introduction of the animals to each other. After approximately 2 weeks, the female began to show proceptive behaviors towards the male. Two other proceptive periods were observed, occuring from 26 to 30 days apart, and lasting for 4-6 days.