Orang­utans: Endan­gered forest dwellers

Profile

Family: Apes (Hominidae)

Genus: Orangutan (Pongo)

Species: Bornean orangutan (Pongo pygmaeus), Sumatran orangutan (pongo abelii), Tapanuli orangutan (Pongo tapanuliensis)

Size: 1.25 m to 1.50 m

Weight: Females 30 to 50 kg, males 50 to 90 kg

Life expectancy: 50 years (in the wild)

Features

Orangutans are the largest tree-dwelling animals on earth. In relation to their body height of about 1.40 m, the peaceful forest dwellers have quite long arms. These are used for easy movement between the branches and trees in the jungle and can reach a wingspan of 2.30 m. The males usually weigh between 50 and 90 kilogrammes, the females only between 30 and 50 kilogrammes. A special feature of orangutans is their reddish-brown fur colouring which distinguishes them strongly from the great apes living in Africa. The cheek flaps which are only found in males and grow particularly strongly after taking over a territory are also extremely species-specific.

Distribution

Several thousand years ago, orangutans still inhabited large parts of the tropical forests of the Asian continent. However, due to large habitat loss and hunting, orangutans are now only found on the two islands of Sumatra and Borneo. The north-western regions and the west coast of Sumatra are the favoured regions of the impressive primates. On Borneo, on the other hand, they mainly inhabit the southern and eastern regions of the island.

Habitat

The tropical rainforests of Sumatra and Borneo provide an almost perfect habitat for orangutans. Particularly regions near rivers or swamps are their preferred home. An important food source for the animals are the so-called dipterocarpaceae which can often be found in large forests with tall trees.

Diet

Orangutans are mainly herbivores and especially prefer fruits. Their teeth make it possible to break open even hard shells or seeds. But young shoots, leaves and bark also make up a large part of an orangutans' diet. Occasionally, however, the primates also eat insects, smaller vertebrates or birds' eggs. Orangutans are extremely aware of what they eat. For example, it has been observed that apes, when suffering from upset stomachs or other ailments, focus on certain medicinal plants that can provide relief from some ailments.

Social behaviour

Orangutans are mostly solitary. If the orangutan is not a mother with young animals, lasting bonds between individuals are unlikely. Males in particular avoid the territories of other males unless they want to fight for mating rights. Orangutan communication is often much quieter than that of other apes. Although the primates make sounds, body language and facial expressions are also an important factor in communication.

Orangutans and humans

The threat from humans has been increasing over the last 30 years. Due to the growing establishment of oil palm plantations, the habitat of the orangutans has shrunk enormously. However, the situation has been improving for some years now and their population is slowly but steadily recovering.
Moreover, humans are increasingly able to understand the gentle forest dwellers. For example, some institutes started to succeed in teaching orangutans sign language and thus communicating with them. Even though detailed conversations were not possible, researchers were still able to learn new things about the animals.