Otto lives in the rainforests of Sumatra with his mum. Orangs are fairly solitary most of the time but Otto has an older sister, Octavia, who lives around in the forest nearby. Sometimes they hang out together. And when a particularly rich fig tree is fruiting he sometimes catches a glimpse of his dad, Oswald, who is a huge adult male, the only one in these parts. Orang-utans live on the islands of Borneo and Sumatra in South-east Asia and are the only great apes found outside Africa. Orang-utans spend most of their time in the treetops of the rainforests -- in fact the name "orang-utan" means "man of the forest".