Sunday, July 6, 2008

Howler monkey


Howler monkeys (genus Alouatta monotypic in subfamily Alouattinae) are among the largest of the New World monkeys. Nine species are currently recognised. Previously classified in the family Cebidae, they are now placed in the family Atelidae.
Howler monkeys range in size from 56 to 92 cm, excluding their tail which can be equally as long. Like many New World monkeys, they have
prehensile tails. They have a lifespan of 15 to 20 years. These monkeys are native to South and Central American forests. They live in groups of usually about 18 individuals. Threats to howler monkeys include being hunted for food and captivity.
As their name suggests, vocal
communication forms an important part of their social behavior. Specifically, the name comes from their distinctive loud barking whoop they make, which can be heard over considerable distances. (As correctly pointed out by William Henry Hudson in his novel Green Mansions, "howler" is a misnomer since the male's voice sounds rather like a powerful roar; female vocalisations sound like a pig's grunt). They have an enlarged basihyal or hyoid bone which helps them make their loud sound. They are considered the loudest land animal. According to Guinness Book of World Record it can be heard clearly for 3 miles.[citation needed] Unlike other New World monkeys, both male and female howler monkeys have trichromatic colour vision.[2]
These large, slow moving monkeys are the only folivores of the New World monkeys. Howlers eat mainly top canopy leaves, together with fruit, buds, flowers, and nuts. They need to be careful not to eat too much of certain species of mature leaf in one sitting, as some of the leaves they eat contain toxins that can poison the monkey.[3]
They move quadrapedally and do not brachiate, usually holding on to a branch with at least two hands or one hand and the tail at all times. Their prehensile tails are strong enough to support the monkey's entire body weight, although they seldom do so. The first 2 fingers of each hand are set apart and are opposable to the other three. They very seldom leave the trees. They rest about 80 percent of the time and are considered the least active of all monkeys.
Howler monkeys live in groups where the number of females is greater than the number of males. Groups may have only one male or several males. Unlike most New World monkeys, juveniles of both genders emigrate from their natal groups,
[4] so neither adult males nor adults females in a group are typically related. Fighting among group members is infrequent and generally of short duration. However, serious injuries can result. Both males and females may fight with each other.[4][5] Group size varies by species and by location, with an approximate male to female ratio of a male to four females.[4]

1 comment:

muskan said...

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