Wild orangutan birth at tanjung puting reserve
During ten years (1971–1981) of research on wild orangutans at the Orangutan Research and Conservation Project study area in the Tanjung Puting Reserve, Central Indonesian Borneo, parturition was observed twice. Observations centered on parturition totalled 1,206 hr and included 95 whole days of observation (when the target individual was followed from nest to nest). The two females who gave birth are mother and daughter, one multiparous, the other primiparous. The 1977 birth to the daughter made the older female who subsequently gave birth in 1979 the first known wild orangutan grandmother. In 1977 the entire birth process was observed while in 1979 only the emergence of the fetal membranes was seen. The females' behavior during parturition as well as prepartum and postpartum was quite different and is described. Parity may account for some of these differences.