Tropical rainforests are one of the oldest habitats on the face of our earth – older than many of the stars. The first programme in the Wild Asia series is set in the tropics of Asia and explores a small area of rainforest in Northern Sumatra. This forest is the realm of our central character, Asia’s largest ape, the orangutan, dubbed the “Red Ape” in honour of its orange-coloured coat.

For the last five years an Indonesian/ British research team have been studying a group of orangutans in this swampy area of rainforest. Their work is the basis of this film.

The research team has given key members of the group names. Andai is nine years old and has just begun to fend for herself. Until now Andai has lived in total dependence on her mother, Arni, whose new baby has now become the centre of her life. Arno is both the new baby and Andai’s father. He is the dominant male in the group and therefore likely to have fathered almost all the offspring.

Arno, Arni and Andai share a most remarkable skill: they use a simple tool – a specially fashioned twig – to overcome problems in prising food from difficult places. The researchers believe that Andai learned how to use tools from her mother Arni, who may have learnt it from Arno or from her mother. Before long Arni’s new baby will probably learn too. These orangutan are the only ones in Sumatra and Borneo who have been observed using tools.

These orangutans are remarkable in another way, for while the red apes have always been regarded as solitary creatures, this group is different. They are much more sociable, congregating for the fruiting season in the swamp forest. Adults socialise with others as though they were friends, and juveniles play together.

The film explores the very special relationship that this group of orangutans have with the forest in which they live. A forest that is, itself, like a huge organism.

The forest breathes in rain and expels oxygen. The canopy of the forest is like a skin. Beneath it, the forest floor is like the gut. Everything ends up here, dead animals, leaves, seeds and droppings and eventually it will all be recycled.

In the Realm of the Red Ape opens with the unique sounds of a primate dawn chorus and follows the red apes through their day as they interact with the forest. It explores the special relationships of the forest as a living organism. It ends as the orangutans settle for the night in the nests they build for themselves in the trees. Each night a new tree, each night a new nest.