The Borneo orangutan is the only great ape found in Asia. Here in Borneo, it shares the rainforest with 12 other primate species including two gibbon species.
Although they more closely resemble monkeys, gibbons are actually called smaller or lesser apes, and like all apes, gibbons lack tails.
Compared to great apes, gibbons are small, exhibit low sexual dimorphism (meaning there’s not much difference in size or appearance between male and female) and do not make nests.
They are also known to be the fastest and most agile of all tree-dwelling, nonflying mammals.
Here are the basic things you need to know about the two gibbon species that can be found in Borneo:
1.Bornean white-bearded gibbon (Hylobates albibarbis)
It is also known as the Bornean agile gibbon or southern gibbon. Before this, it was considered as a subspecies of the agile gibbon (Hylobates agilis). However, based on DNA research it is classified as a completely different species.
They are commonly seen with grey or dark brown fur, a black face and white beard.
According to Borneo Nature Foundation, gibbons are harder to study than orangutans because they travel very quickly through the forest canopy and are difficult to habituate.
It is crucial to study more about this particular species of gibbon since it is an endangered animal.
Additionally, it is endemic only to southern part of Borneo, between the Kapuas and Barito rivers.
Additionally, the Bornean white-bearded gibbon is endemic only to southern part of Borneo, between the Kapuas and Barito rivers.
Sixty-five percent of their diet comprises fruit, while 23% is made up of leaves and insects.
They rely heavily on dense and tall forest areas for safety and travelling. Hence, logging and mining are huge threats to their survival.
Gibbon Behaviour Project by Borneo Nature Foundation is the only project in the world dedicated to the long term study of Bornean white-bearded gibbon.
After a large part of the forest habitat was lost to fire, the gibbons had to fit into a smaller space and forced to compete for more food and other resources.
Just like humans during home intrusions, some of these gibbons were moving to a new area after the fire and raising conflicts with other groups.
2.Mueller’s gibbon or Bornean gibbon (Hylobates muelleri)
According to A Field Guide to the Mammals of Borneo by Junaidi Payne and Charles. M Francis, Hylobates muelleri is basically grey-brown but with a wide range in coat colour and pattern.
It is endemic to the island of Borneo and can be found in the northern and eastern part of the island.
In Indonesia, they are distributed in a number of protected areas including Betung Kerihun National Park, Bukit Baka Bukit Raya National Park, Kayan Mentarang National Park, Kutai National Park, Sungai Wain Protection Forest and Tanjung Puting National Park.
Meanwhile in Malaysia, Hylobates muelleri occurs in Pulong Tau National Park, Lanjak Entimau Wildlife Sanctuary and Semenggoh Nature Reserve.
How do you spot this mammal in the forest? Payne and Francis stated that they are most often detected by the loud, bubbling call of the adult female, heard during the first hours of daylight and carrying for a distance of over 2km under suitable conditions.
Their diets are mainly made up of fresh, ripe fruits, young leaves and small insects.
They are social animals, just like all primates. Plus, all gibbons are strongly territorial. Mueller’s gibbons usually can be found in small groups consisting of one adult male, one adult female and one to three young.
Each group defends a territory of 20-30 hectare. So, it is sad and depressing to see them after being rescued in a small, confined cage such as in Matang Wildlife Centre.
They wouldn’t be there in the first place if it weren’t for irresponsible human acts like keeping them as pets or wildlife trafficking.