The proboscis monkey (Nasalis larvatus) or long-nosed monkey, known as the bekantan in Indonesia, is an arboreal Old World monkey with an unusually large nose, a reddish-brown skin color and a long tail. The nose of the proboscis monkey evolved because of sexual selection. The nose of a male proboscis monkey can exceed 3.9 inches (10 centimeters), and is thought to woo females. Proboscis monkeys live in a harem consisting of one dominant male and around 5 or 6 females and their offspring. Proboscis Monkeys: The word 'proboscis' means a long or protruding snout or nose. Proboscis monkeys are preyed on … It is endemic to the southeast Asian island of Borneo and is found mostly in mangrove forests and on the coastal areas of the island. They rest during the day and at night they gather and sleep in the safety of thick branches that hang over water. As proboscis monkeys live in waterways throughout the coastal areas of Borneo, they are adapted to swim. It is known to jump off branches and descend into water. They have large, chambered stomachs that contain bacteria to break down their food. Behaviour. The proboscis monkey … The proboscis monkey is … The word proboscis means nose and these monkeys sure do have big ones, especially the adult males. The proboscis monkey spends most of its life in the trees. Proboscis monkeys live in groups called harems, that usually consist of a male and around seven females, and young. Monkeys live all over the world and come in … Their distinct characteristics do not end there, however. It is a true signal of a male’s body and testis size and there is a correlation between nose size and the number of females a male has . Proboscis monkeys generally live in single-male or male-only bands or harems, of up to 60 and 19 monkeys respectively, and the females give birth to their young most commonly during night or early in the morning. How long does a proboscis monkey live? The average weight of females is 25 pounds. Births usually occur at night. The proboscis monkey walks on all fours and is a capable climber. The basic social unit in proboscis monkeys is a single adult male with from 2 to 7 adult females. Proboscis monkeys eat leaves, unripe non-fleshy fruit, seeds and occasionally insects. Proboscis monkeys, called bekantan in Indonesia, and sometimes otherwise referred to as long-nosed monkeys, are endemic to Borneo, including all three nations that divide the island – Brunei, Indonesia, and Malaysia. (Bennett and Sebastian, 1988) Mating System; polygynous; Proboscis monkeys give birth to a single offspring after a gestation of 166 days. They are crepuscular, which means active in the early morning and just before nightfall. The males mate with females in their social group. LEARN MORE ABOUT PROBOSCIS MONKEYS > Jaguars are one of the proboscis monkey’s predators. Proboscis monkeys are diurnal, preferring to be active from late afternoon until dark. The proboscis monkey is largely arboreal and moves quadrupedally and by leaps. It spends most of its time in the trees, and will leap from branch to branch as well as climb in order to get around. Proboscis monkeys are highly selective feeders, and have a specialized chambered stomach (sacculated stomaches) that allows them to eat foods other primates cannot. An elephant's trunk is a proboscis. Proboscis monkeys are one of the largest primates in Asia. Proboscis monkeys live in groups consisting of one male, one female, and their children. Male proboscis monkeys can weigh up to 50 pounds. Proboscis monkeys are perhaps the most aquatic of the primates.