Why do baby red langur monkeys change colour?

Research Blog

Written by Eka Cahyaningrum (BNF Primate Scientist)

Red langur monkeys (Presbytis rubicunda) can be found on the islands of Borneo and Karimata. This species also lives in the Sebangau Forest where we conduct primate behaviour research and other biodiversity studies.

The babies of this species are born snow white. The young animals’ fur begins to change to reddish-orange starting with its tail. The colour then spreads over its back to the whole body, so for a short period of time, it looks quite strange with only a bright orange tail.


The snow white baby red langur in Sebangau. Photo: BNF | LLG UPT CIMTROP


Adult langurs have reddish-orange fur, with a wrinkly black face and white chin that makes them look like an overthinking-grumpy monkey. There are some theories as to why these animals are born with a different fur colour than adults. It has been suggested that it keeps the youngsters safe from predators, stopping them getting separated from their mothers and even sending out a signal to the rest of the troop that they should start to think about childcare duties.

Some experts suggest the sheer spectacle of these langurs may encourage older females to look out for – and take better care of – the babies in their group.


Mother and infant red langur in Sebangau Forest.Photo: BNF | LLG UPT CIMTROP


The plight of this entire species is certainly worth caring about. Red langurs are classified as ‘Vulnerable’ as a result of their natural habitats being destroyed by logging and forest fires, while people also hunt them for meat and keep them as pets.

Thanks to support from Primate Conservation Inc. (PCI), we will be able to conduct more population surveys of this species in Sebangau Forest and continue the research we’ve carried out for over 10 years. We will use the result to provide detailed information about the red langur monkey population and will update their current conservation status in Sebangau Forest.


Male red langur in Sebangau
Photo: Andrew Walmsley | BNF | LLG UPT CIMTROP