Brown howling monkeys, like other howler monkeys, are best known for their impressive howls, which can be heard for over 1.6 km and are often mistaken for roars of lions by visitors to the area. Far from being dangerous predators, these primates are placid, arboreal vegetarians that live in social groups. There are ten species of howler monkeys, which can be identified by their coat color. As expected, brown howling monkeys have brown coats, though the color may vary from brown to dark red or black. The hair is lighter and sparser on the belly, and the face and ears are dark and bare. Like other howlers, they have large stocky frames. The males are considerably larger than the females. Their tails are long and prehensile, and lack fur on the underside near the tip. These amazing features allow brown howling monkeys to hang from their tails and use them as an anchor while feeding.