Hylobates moloch
silvery gibbon

Molochs, Hylobates moloch, are endemic to the Indonesian island of Java.

Gibbons live in the tropical rainforests and semi-evergreen rainforests of South and Southeast Asia. Hylobates moloch is found in the tropical rainforest in Java. It is found in the upper canopy of the lowland and hill forests. Gibbons spend most of their lives in trees, and rarely descend to the forest floor.

Adult molochs weigh on average 8 kg. There is no apparent sexual dimorphism (size or color difference) between males and females. Both male and female are a silverly-gray color and possess a dark gray cap. Molochs have long arms and lean bodies, both of which are especially important while they are manuvering through the canopy of the rainforest.

Gibbons are typically monogamous.

The available data on gibbons show no birth seasonality. A mated gibbon pair will produce an average of 5 to 6 offspring over their reproductive lifespan of about 10 to 20 years. Like most primates, H. moloch produces one young per litter, with a gestation length of around seven months. The interbirth period of a reproductive female is about 40 months.

Although no specific information is available, most female gibbons nurse their offspring until the offspring are about two years old. Offspring leave their natal group when they become sexually mature.

Other species in this genus are reported to live as long as 44 years in captivity. Hylobates moloch is probably similar.

Gibbon groups are usually small, consisting of the mated pair, an infant and a juvenile, making the average group size about four individuals.

They are highly territorial and defend their territories by "singing." These loud calls can often be heard up to a kilometer away. Both male and female molochs call during territorial disputes. During these disputes, the female calls loudly, a "great call" and scream, while the male approaches the intruder and chases it away.

Vocal communication is prevalent in all gibbon species. Mated pairs use duets to mark their territory and announce their presence to conspecifics. In addition to vocalizations, gibbons use facial expressions and body postures in communication. Tactile communication is of some importance between mates, as well as between parents and their offspring.

Along with other gibbon species, H. moloch is frugivorous, feeding on ripe fruits in the upper canopy of the tropical rainforests. Molochs have also been observed eating leaves and flowers. Being frugivorous poses certain problems because fruit patches are found in small, scattered areas throughout the rainforest. Gibbons have adopted a rapid form of locomotion, brachiation, in which they swing by their long arms from branch to branch. This rapid form of locomotion helps gibbons to travel rapidly and effeciently from one food source to another.

Details on predation of these animals are not available. However, we can speculate that because they use the high canopy of the rainforest, where branches might support the weight of large animals, their predators are probably small or avian.

The role these primates play in their ecosystem has not been detailed in the literature. However, it is likely that through their frugivory, they play some role in seed dispersal.

Hylobates moloch is not an important economic resource for humans. This species is not used for biomedical research, unlike some other primate species. Molochs are sometimes hunted for meat, and illegal poaching does occur for the pet trade.

These animals are not known to have a negative effect on humans.

This species is endangered. The biggest threat to gibbons is deforestation of the tropical rainforests. Habitats are disappearing at an astonishing rate due to logging and agricultural demands. Without a sufficient range, gibbon species, along with other tropical species, are finding it much harder to exist. In an effort to help save these primates, reserves and parks are created, but there is no conservation program specifically for H. moloch. Other threats to gibbons include hunting for meat, and illegal poaching for the pet trade. These threats, although serious, are secondary to deforestation.