Three Miles!

Howler Monkeys are the loudest terrestrial animals in the Western Hemisphere. Their calls can be heard up to three miles away, thanks to a large hyoid bone (Adam’s apple) which amplifies the sound. Males have much larger hyoid bones and thus make louder calls than females. Howler monkeys call to establish territory and as a response to disturbances. Groups of howler monkeys can typically be heard calling back and forth in the early morning and at dusk.  

Hanging Out

A howler monkey’s tail is prehensile (grasping) and acts like another arm, allowing the monkey to swing, grip and even hang upside down by its tail alone. The underside of the tip of the tail lacks hair and has a textured surface. This creates friction and helps the monkey get an even stronger grip.

Who’s Who

Black howler monkeys display sexual dimorphism, meaning males and females appear physically different. Males have black fur and females are blond. Both sexes are blond at birth. As males mature, their coats change to black, usually at about two years of age. A male black howler monkey’s larger hyoid bone is also an example of sexual dimorphism.