A predominantly solitary creature, the Bornean orangutan occupies large overlapping home ranges where it spends almost all of its time in the trees, clambering between branches or using its body weight to bend and sway trees (2). Each night, the Bornean orangutan builds a nest from bent branches on which to sleep, high up in the trees (2) (7). An extra layer is added to cover the individual if it is raining (2).
Orangutans are the slowest breeding of all mammal species, with an inter-birth interval of approximately eight years (2) (8). They are long-lived, and females tend not to reproduce until they reach 15 years of age (2). The female Bornean orangutan is thought to prefer to mate with a dominant, flanged male, and will seek one out (4). However, other male orangutans may force matings should they encounter a lone female (2) (4).
The female Bornean orangutan gives birth to a single young after a gestation period of 235 to 270 days (2). The infant spends its first two to three years being carried constantly, and will still remain close to the female for at least another three years (2) (8).
The orangutan’s diet includes over 400 types of food, with fruit such as wild figs (Ficus spp.) and durians (Durio spp.) forming around 60 percent of its diet (2) (8). Leaves, shoots and invertebrates are also taken, and the Bornean orangutan will occasionally feed on mineral-rich soils (2).