And unlike other primates, orangutans build nests. They do this for two main reasons. First, to avoid sleeping on the ground, where they can be assailed by insects and other creatures. And second, because they lack a tail, and their size can make them unstable when they fall asleep in trees. It is not uncommon for young orangs to fall from their nests a few times before they master tree sleeping.
Orangutans are only one of the rainforest's numerous inhabitants.
During the day, massive animals like Asian elephants and Sumatran rhinos can be found journeying through the undergrowth. The Sumatran rhino, on the other hand, is a native, though there are so few rhinos remaining that until recently, they were believed extinct. With the arrival of night, spiny-tailed porcupines, mousedeer, and fish owls emerge from their diurnal hiding places, searching for food. No nocturnal creature is more unusual than the flying squirrel. Flaps of skin stretch between the squirrel's front and rear legs, and when the squirrel leaps from a tree, it glides on its skin membranes, sometimes for distances of more than 300 feet.