[3] The population in the Santa Cruz Department in Bolivia was split off as a separate species, the Bolivian red howler, in 1986,[4][5] and more recently, splitting off the population in northeastern South America and Trinidad as the Guyanan red howler has occurred.

The position of the foramen magnum is very posterior to make way for the expanded jaw and enlarged hyoid bone.

Howler monkeys also have an inflated bulla, which is the bony encasement of the middle ear.

The diurnal Alouatta seniculus is an arboreal primate, so it spends much of its time high in the canopy.

Venezuelan red howlers are most active in the morning, when the group is on the move to find another feeding spot.

[6] A. seniculus monkeys are folivores, which means their diets mainly consist of leaves, but they also rely on nuts, small animals, fruits, seeds, and flowers for important nutrients.

These howler monkeys are able to eat the fibrous leaves due to the structural aspects of their dentition.

Narrow incisors aid in the ingestion of the leaves, and molars with sharp, shearing crests help them to better chew their food.

[6] The hindgut contains bacteria that digest leaves and makes up a third of the Venezuelan red howler's total body volume.

[6] Like other New World monkeys, the Venezuelan red howler's dental formula (maxilla and mandible) is two incisors, one canine, three premolars, and three molars.