RANGE Eastern Bolivia, southern Brazil and Paraguay, and northern Argentina
HABITAT Prefer tall, aged forests; occupy the middle and upper canopies of the trees
DIET Canopy leaves, fruits such as figs and plums, buds, flowers and sometimes nuts
Males and females are sexually dimorphic; adult males are black, adult females and juveniles are a golden tan color. They are arboreal, diurnal, and have a prehensile tail.
Troop sizes range from 3 to 19. Troops commonly have 1 to 3 adult males and 2 to 7 adult females.
Howler monkeys are the loudest primates in the Americas. Males do most of the howling. They can be heard 1.8 miles away in the forest, and 3 miles away over water.
The hyoid bone in their throat is modified and forms a bony box called a corniculum. The corniculum is an egg-shaped pouch that acts as an amplifying chamber, enabling these monkeys to out-howl all other land animals. They use loud howls, grunts, roars and barks to defend territory.
Black howler monkeys face threats from habitat loss due to agricultural development.
