howler monkey

Howler monkeys (genus Alouatta monotypic in subfamily Alouattinae) are among the largest of the New World monkeys. fifteen species are currently recognised. Previously classified in the family Cebidae, they are now placed in the family Atelidae. These monkeys are native to South and Central American forests. Threats to howler monkeys include human predation, habitat destruction and being captured for captivity as pets or zoo animals.
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. Unlike other New World monkeys, both male and female howler monkeys have trichromatic color vision. This has evolved independently from other New World monkeys due to gene duplication. They have a lifespan of 15 to 20 years. Howler species are dimorphic and can also be dichromatic (i.e. Alouatta caraya). Males are, on average, 1.5 to 2 kg heavier than females.
Howler monkeys generally move quadrupedally on the tops of branches, usually grasping a branch with at least two hands or one hand and the tail at all times. They have strong prehensile tails which are able to support the monkey's entire body weight. However, fully adult howler monkeys do not often rely on their tail for full body support whereas juveniles do so more frequently.

These large and 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. Howler monkeys are also known to occasionally raid birds nests and chicken coops and consume the eggs