Age-Sex Class Differences in the Positional Behaviour of the Sumatran Orang-Utan (Pongo pygmaeus abelii) in the Gunung Leuser National Park, Indonesia

Abstract
During a three-year field study of the socio-ecology of Sumatran orang-utans, their use of the canopy was investigated in the Gunung Leuser National Park, Indonesia. This paper concerns the positional