Proboscis monkeys could significantly decline if deforestation in Borneo increases.

The monkeys live in swamp forests, mangrove forests and riverine forests in lowland areas and are under increasing threat as more land is logged or converted to agricultural use.

Researchers project that if deforestation and hunting continue the population of monkeys in the Lower Kinabatangan Wildlife sanctuary could decline by more than 1000 in the next 50 years. The population is currently 3000.