Sumatran orangutans (Pongo abelii) are one of our closest living relatives and the most intelligent non-human great ape. They are classified by the IUCN as Critically Endangered and are among the 25 most endangered primates in the world. Around 90% of all remaining Sumatran orangutans live in the Leuser Ecosystem and they are under imminent threat of extinction with the current rate of habitat loss. Sumatran orangutans are almost exclusively arboreal, or tree dwelling, and need large rainforest trees for locomotion, food and sleeping sites. Orangutans have the slowest life histories of any mammal except for humans. Because they are not a social species and learn through observation, they need to spend a minimum of seven years with their mother before they have the necessary skills to survive on their own. Orangutans only have one offspring at a time every eight to nine years so populations are naturally slow growing.
Orangutans are frugivorous and play a key role in healthy ecosystem function through seed dispersal over a huge range. If orangutans disappear, so too will certain tree species. Orangutans are threatened by habitat loss and hunting despite legal protection status since 1931 in Indonesia. As forest is increasingly encroached on and converted into agriculture and cultivated, orangutans come into conflict with humans through crop raiding. Often gardens and farms have no forested perimeters, making the boundary between agriculture and forest indistinguishable. When females are killed their babies are taken and sold into the illegal pet trade. Sumatran orangutans are a key focal species for The Sumatran Ranger Project. Together with Sumatran elephants, they form the top two species involved in human-wildlife conflict in our focal communities along the buffer zone of the Leuser Ecosystem.