Howler monkeys lives in the northeast of Argentina, in eastern Bolivia, in eastern and southern Brazil and Paraguay. Together with a brown howler, this species is the southernmost of all representatives of the genus of howler.
Form groups of three to nineteen individuals (an average of seven to nine). For every three males in the group, there are usually seven to nine females.
The howlers sounded their name because of the ability to make loud roaring sounds. These sounds are used for communication, and can be heard from a distance of five kilometers.
They spend 70% of the day in drums, which makes them one of the least active primates of the New World. They live on trees, preferring dry forests. In the diet, mainly leaves, as well as fruits. The tail is of a grasping type, used as an additional limb when moving in tree crowns. On the ground they go down rarely, they get water, moistening their hands with dew and wood juices and licking the moisture from their hands. Life expectancy up to 20 years.
Some of the wool has marks of reddish-brown or dark-yellow color. Cubs are born with golden fur and change color when growing up. The tail is long, of a grasping type, and naked from below. The face is also hairless. Like other howlers, these animals have a unique voice device, which allows them to make loud roaring sounds.