The Bornean gibbon (Hylobates muelleri) is a gibbon that inhabits the rainforests of Borneo. Its arms are very long and it moves swiftly by brachiation, covering about 3 m in a single swing. It is diurnal and primarily eats ripe fruit; it has no tail and therefore lacks a prehensile tail. It typically holds territories as pairs or small groups and the pair sings in the morning to assert their territory. The gestation period is about seven months, and the species is classified as Endangered (IUCN Red List category I B).