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Proboscis Monkeys are confined to the island of Borneo, Indonesia and Malaysia. They prefer coastal regions to inland areas and inhabit mangrove forest along rivers and estuaries, swamp-land, and lowland rainforest. Proboscis Monkeys are sexually dimorphic. Males have a large protruding nose, which enhances vocalizations through resonance. The nose of the female is smaller. The fur of the adult Proboscis Monkey is pink and brown with red around the head and shoulders. The arms, legs, and tail are gray. Males have a black scrotum and a red penis. Infants are born with a blue colored face. Proboscis monkeys have webbing between the digits to allow for swimming. The basic social unit in Proboscis Monkeys is a single adult male with a harem of from 2 to 7 adult females. The males mate with females in their social group. Proboscis Monkeys give birth to a single offspring after a gestation of 166 days. Births usually occur at night. The female sits on a tree branch during the birth. After the infant is born, the mother consumes the placenta. Infants stay close to their mothers for about one year. The lifespan in captivity is at least 23 years. Proboscis Monkeys are diurnal, preferring to be active from late afternoon until dark. They are primarily arboreal although they are never more than 600m from a river. When moving through the trees, they are quadrupedal. These monkeys are good swimmers and will leap out of the trees into the water. They may cross rivers by swimming if alone or they may cross by jumping from a tree on one bank to one on the other side at narrow points if in a group. There are two types of groups within the Proboscis Monkey society: unimale and all-male. These groups number 3-32 individuals. Several of the groups will come together in the evening to sleep. These multigroup gatherings are called bands. Proboscis Monkeys sleep 0-15m from the river's edge. They do not sleep in the same place on consecutive nights. The same groups associate regularly and there is little aggression between males in unimale groups. The Proboscis Monkey has several sounds for communication. Growls are made by males and are used to calm the group members. Honks are made by males as a threat or to warn of predators. Shrieks are made by females and both sexes of juveniles to show aggitation or excitement, and screams are given during agonistic encounters. Social grooming is performed, usually between females. They prefer fruits, seeds, young leaves, and shoots of mangrove. They may also eat some invertebrates such as caterpillars and larvae. Leopards are known to prey upon them, as are crocodiles. Adult males sometimes vocalize, apparently to scare off potential predators. Proboscis Monkeys are protected from hunting and capture in Borneo but the destruction of the mangrove forest has limited the population. They are listed as Appendix I by the Convention on International Trade in Endangered Species (CITES). They are listed as endangered by the International Trade in Endangered Species of Wild Fauna and Flora (IUCN). Design of the cheeky Proboscis Monkey in his tropical hide out by Ro London. |