Black Howler Monkey

Alouatta caraya

Range: Interior of southern Brazil through Paraguay to northern Argentina.

Vocalization: The howler monkeys get their common name from their ability to emit thunderous calls that are used in part to mark their territory. They are capable of making these great sounds because they have two egg-sized hollow hyoid bones in their throat that act as resonating chambers. The adult male howler monkeys initiate howling, but all members of the 10 to 20 monkey clan may then join in.

Characteristics: Howler monkeys are strictly arboreal animals and are one of several species of New World monkeys equipped with a prehensile tail. Although capable of brachiating and leaping, they prefer a more trundling type of movement (being sure of handhold on a new tree limb before releasing their feet and tail from the old limb) as they move single file along their treetop “roads.” However, when the clan comes to a break in the trees, the adult howlers may form a hand-to-tail monkey bridge so that the juveniles can safely cross.

Howler monkeys are highly territorial, marking their area by howling at rival clans, but seldom fighting with other clans. Adult females outnumber males by two or three to one. The clans have a somewhat loose social hierarchy, but the adult male leaders do enforce clan rules of conduct and direct communal activities.

Within the clan, howlers communicate by blinking eyelids, waggling tongues and making clicking sounds. They are diurnal monkeys but are quite sedentary, even in the wild.

Reproduction: Gestation is somewhere between 140 and 195 days. One baby is the normal litter size. A newborn howler will cling to its mother’s belly for about a month and then shift to her back. The young will nurse for about a year. Mothers have complete charge of their young, but the entire clan will come to the aid of a baby that falls.

Diet: Leaves, fruit and vegetables.