Gibbons are forest dwellers and are well known for their habit of swinging between the branches of the rainforest on their long arms, a method of locomotion known as brachiation (4). Gibbons are also adept however, at walking upright, both on the ground and in the trees (2). Black-crested gibbons live in small family groups consisting of a monogamous male and female and their offspring, there are also reports that groups may contain additional mature females (4). These apes are predominantly arboreal and the group forages and sleeps amongst the trees (2). Led by the female, the breeding pair partakes in vigorous bouts of singing in the morning, which hauntingly echo through the forest. It is believed that these 'duets' are essential in pair bond formation and reinforcement, but also serve to advertise the presence of the group within the territory (2). A single young is born every two to three years and the infant is usually weaned once it reaches 2 years old (2). Black-crested gibbons feed preferentially on ripe sugar rich fruit such as figs (Ficus spp.), although they also supplement their diet with leaves and insects (2).