Delacour's Langur - Behaviour

Behaviour

Delacour's langurs are diurnal, often spending the day sleeping in limestones caves, although they will sleep on bare rocky surfaces if no caves are available. They are folivorous, without about 78% of the diet reportedly consisting of foliage, although they will also eat fruit, seeds, and flowers. It has been reported that the monkeys will eat leaves from a wide range of different plant species, indicating that their apparent dependence on limestone habitats is not related to their diet.

In previous decades, Delacour's langurs were reported to live in troops of up to thirty individuals, often including a mix of males and females, although single-male groups are more common, and some small all-male groups have also been reported. In more recent years, the typical group size seems to be much smaller, with only about four to sixteen members each. Males defend the troop's territory from outsiders, often standing watch on rocky outcrops. When potential rivals are spotted, the males in a troop initially try to intimidate them with loud hoots and visual displays, resorting to chasing and fighting if this fails. Within the group, social bonds are maintained by grooming and play.

Despite living in forested habitats, Delacour's langur is primarily terrestrial, only occasionally venturing into the trees. They swing by their hands when travelling through trees, and use their tail for balance when scrambling over steep rocky terrain, which may allow them to move more rapidly than other related lutungs.