Howler monkeys are among the largest of the New World monkeys. Nine species are currently recognised.
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.
Howler monkeys have a short snout, and wide-set, round nostrils. They 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.
They move in fours 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. 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, so neither adult males nor adults females in a group are typically related.
As their name suggests, vocal communication forms an important part of their social behavior. They have an enlarged basihyal or hyoid bone which helps them make their loud sound.
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.
Howler monkeys are also known to occasionally raid birds’ nests and chicken coops and consume the eggs.