Presbytis melalophos
mitred leaf monkey

Presbytis melalophos is found in the rainforests of the Malay Peninsula, Sumatra, and western Borneo. (Oates, et al., 1994)

Mitred leaf monkeys inhabit lowland and submontane dipterocarp and evergreen forests. They are also found on the margins of rivers. They prefer discontinuous understory at approximately ninety feet from the ground, but are occasionally found in the continuous main canopy and the highest, emergent layers of the forest. ("Old World Primates", 1990; Aimi and Bakar, 1996; Richard, 1985)

Like all members of the genus Presbytis, mitred leaf-monkeys have a short rostrum and weakly-developed brow ridges. Mitred leaf monkeys have long forelimbs and relatively long hindlimbs, which is consistent with their preferred mode of locomotion, leaping and brachiation. They have long, bicolored tails and weigh an average of 6.0 kilograms. Males weigh only slightly more than females. Mitred leaf-monkeys are distinguished from other Presbytis species by their single-phrase call, pelage characters, and skull features such as long nasals and narrow interorbitals. (Bennett and Davies, 1994; Aimi and Bakar, 1996; Bennett and Davies, 1994; Meijaard and Groves, 2004)

Presbytis melalophos has brownish-gray pelage with the ventral side lighter than the dorsum. The tail is bicolored and the head has a distinct black crest. There are four subspecies of Presbytis melalophos based on pelage differences, distinctions in vocalizations, and geographic location. P. m. bicolor is the whitest subspecies and P. m. sumatrana is the darkest subspecies. The pelage color of P. m. mitrata and P. m. sumatrana is intermediate. Neonates are white with a pale face and a dark, reddish-brown spinal stripe. ("Old World Primates", 1990; Aimi and Bakar, 1996; Meijaard and Groves, 2004)

Mitred leaf monkeys live in single-male groups with five to seventeen females. The single male of the group mates with females in the group. Females exhibit no external sign of estrus and solicit copulation. (Newton and Dunbar, 1994)

General reproductive behavior, including breeding season, number of offspring per breeding season, gestation period, and age at sexual maturity, has not been studied in P. melalophos. In other colobines, males reach maturity at 34-47 months and females reach maturity at 35-60 months. Gestation period is 155-226 days. Most colobines that have been studied breed throughout the year, with 16-25 month interbirth intervals. In Presbytis thomasi, a close relative of P. melalophos, females give birth to one offspring per interval. The young are weaned at 12-15 months. (Matthews and Myers, 2004; Newton and Dunbar, 1994)

In many colobines, infants are transferred between the mother and other group females; however, this behavior has not been observed in P. melalophos. Females nurse and care for their young until they become independent. Immature males disperse from their natal group when they are half-grown, while females remain in their natal group. The role of male mitred leaf monkeys is unclear in raising young. (Newton and Dunbar, 1994)

There is little available information on the lifespan of P. melalophos, either in the wild or in captivity.

Mitred leaf monkeys live in groups consisting of one male and five to seven females. Groups with smaller home ranges are generally more territorial than groups with larger home ranges; territoriality is directly related to the supply of resources. Males identify the group's territory with vocalizations and displays. When groups approach each other, harem males will call to each other and may become physically agressive. Males may also be solitary or live in all-male bands. Solitary males are chased away from females by harem males and are generally confined to a resource-poor area of the forest. ("Old World Primates", 1990; Bennett and Davies, 1994; Van Schaik, et al., 1992)

Females determine their group's movement and are responsible for encounters with another group. However, females remain uninvolved in intergroup conflicts. Females in a group show no evidence of a dominance hierarchy. (Van Schaik, et al., 1992)

Mitred leaf monkeys are arboreal. They spend most of their time in the understory of the forest, leaping between small branch supports and are primarily active during the day. (Fleagle, 1979)

Home ranges are 14-30 hectares; groups may travel up to 950 meters in a day. There is a 20-30 percent overlap of home ranges but an overlap of 79 percent has been recorded. Habitat destruction has resulted in greater home range overlap and increased territoriality. (Johns, 1986; Van Schaik, et al., 1992)

Males announce their territory to other groups in the area with loud calls and distinct leaps. Males of neighboring groups call in chorus at intervals throughout the night. Males also call when two groups approach each other. These territorial calls are quite distinct from the alert calls sounded by a group member when a predator is spotted. ("Old World Primates", 1990; Bennett and Davies, 1994)

Mitred leaf monkeys are frugivorous and folivorous. Fruit comprises 50-60 percent of the diet; the rest consists of leaves and, occasionally, seed and flowers. The foregut is enlarged and has the capacity for microbial fermentation. Presbytis melalophos feeds from up to 197 different tree species. It prefers new leaves to mature leaves. (Bennett and Davies, 1994; Richard, 1985)

The main predators of P. melalophos are birds of prey, including Spilornis cheela, and snakes in the genus Python. When a member of the group detects a predator, it issues an alert cry to other members of the group. The harem male attempts to distract the predator with loud cries and leaps, drawing the predator away from the rest of the group by as much as 240 feet. ("Old World Primates", 1990; Bennett and Davies, 1994)

The diet of P. melalophos includes lots of fruits, the seeds of which are dispersed in its feces. (Bennett and Davies, 1994)

Little information is available on the benefits provided to humans by P. melalophos. They are important members of healthy ecosystems.

There is little information available on the adverse affects of P. melalophos on humans. However, because its diet consists of fruits and leaves, P. melalophos may be a potential crop pest for farmers near its territory.

Presbytis melalophos is highly vulnerable to habitat loss, especially due to the logging industry. Logging decreases the density and availablility of food supplies, altering the behavioral ecology of P. melalophos. In areas where logging has occurred, groups must range more widely or fission into smaller subgroups to forage. After selective logging, groups often reoccupy forested territories. Habitat loss also occurs as a result of spreading agriculture and human development. (Davies, 1994; Eudey and Members of the Primate Specialist Group 2000, 2004; Johns, 1986)