Female black howler monkeys have yellow-brown or olive colored hair, while males have black hair. Infants are born with a golden coat, which changes as the animal matures. They have long, strong prehensile tails which are useful since they rarely come down from the trees.
Alouatta caraya are found in the rainforests of central South America ranging through eastern Bolivia, southern Brazil, Paraguay, and northern Argentina. Their habit of howling in the morning is thought to be a way of marking their territory.