“THE FLYING MAMMAL”

Two speciesof orangutan
There are two species of orangutan - the Bornean and Sumatran - which differ a little in appearance and behavior. While both species have shaggy reddish fur, Sumatran orangutans have longer facial hair.
Sumatran orang-utans are also reported to have closer social bonds than their Bornean cousins. The Sumatran orang-utan is almost exclusively arboreal. Females virtually never travel on the ground and adult males do so only rarely. This is in contrast to Bornean orang-utans, especially adult males, which more often descend to the ground.

Sumatran Orangutan (Pongoabelii) female swinging through the trees with male baby in GunungLeuser National Park, Sumatra-Indonesia
©Naturepl.com/Anup Shah / WWF

Social structure
They live in primary and secondary forests. Although they can occur up to 1,500m above sea level, most are found in lowland areas and prefer forests in river valleys or floodplains.
Orang-utans travel by moving from one tree to another, and usually avoid climbing down to the ground. But when they do, they move on 'all fours', placing their clenched fists on the ground.
Orang-utans make a nest of vegetation to sleep in at night, and rest in smaller nets during the day.
Adults are generally solitary, although temporary aggregations are occasionally formed. Males' large home ranges overlap with the ranges of several adult females. Adult males are generally hostile to one another, although they do not display territorially.

Bornean Orangutan (Pongopygmaeus)
©Wikipedia