Alouatta caraya
black howler monkey

Alouatta caraya are found in the rainforests of central South America ranging through eastern Bolivia, southern Brazil, Paraguay, and northern Argentina.

(Walker 1999)

Alouatta caraya range varies from tropical semi-deciduous gallery forest where rains are nearly constant throughout the year, to tropical deciduous forest spotted with savanna like openings where there is a marked wet, warm season and a dry, cool season. A. caraya require forests with diverse species of plant life to supply their dietary needs. Much of their habitat is currently being diminished by destruction of these forest types. (Welker et al. 1990, Rodrigues and Marinho-Filho 1995, Kowalewski and Zunino 1997)

Alouatta caraya are sexually dimorphic where males average 6.7 kg and females average 4.4 kg. Male body size ranges from 1.7 to 2.2 ft with tails of similar length to their body. Females' bodies average 1.6 ft with tails slightly longer than their bodies. A. caraya are also sexually dichromatic. Males usually have black hair, which gives the species the common name of Black Howler monkey. Females however have more yellow-brown or olive colored hair. Infants are born with a golden coat, which changes as the animal matures. A. caraya have long, strong prehensile tails. These tails are hairless on the underside, which allows them to be sensitive to touch and act in identifying things, much like a 5th hand. The black face is mostly hairless as well, with slightly bushy eyebrows. A. caraya have brown, medium sized eyes set in a frontal position. The muzzle is prominent and the nostrils close together. Like other howlers they have enlarged hyoid and larynx housing the vocal apparatus where the distinctive howling originates. A. caraya however, have less prominent lower jaw and bulging neck than some howlers.

(Welker et al. 1990, Walker et al. 1999, Bicca Marquez and Calegaro Marquez 1998)

The mating system of Alouatta caraya appears promiscuous among the members of the group.

Gestation length for A. caraya is 187 days. Studies have shown that younger females have gestation length of 10 to 12 months where more mature mothers have gestation length of only 7-10 months. Females give birth to one offspring per birth and care for infants for about one full year before mating again. Infants are about 125 g at birth.

(Welker and Schafer-Witt 1990, Shoemaker 1979)

Females care for their young for about 12 months after they are born. Female offspring remain in their natal group and therefore stay with their mother long after they are independent.

Most howler monkeys live in large social groups generally made up of family members. These groups appear to be matrilineal where the males disperse to non-natal groups, though not always. In Alouatta caraya groups there are usually between 5 to 8, though they have been observed in the wild in groups up to 19 individuals. The groups have roughly equal sex ratio but may tend to have more females than males. A. caraya practice allomothering where other females will carry, groom and protect infants other than their own. Adult males are also sometimes seen alloparenting. Young males are not allowed to handle infants since they often mistreat or even kill them. Overt conflict has rarely been observed in A. caraya. It does however arise between young males at the time in their life that some set out to join other troops. A. caraya are territorial but seem to only defend the immediate area where they are at the time, and territories often overlap. All members of the group "howl" each morning to notify neighboring groups of their position presumably to maintain distance between groups. A. caraya have also been observed defecating, sometimes forming huge dung piles, in the mornings and evenings, and rubbing themselves on branches. This behavior is thought to be a way of marking territory.

(Welker et al. 1990, Shoemaker 1979, Erwin and Mitchell 1986, Calegaro Marques and Bicca Marques, 1993)

Alouatta caraya are folivorous. They eat mostly leaves but do compliment their diet with fruits, buds and flowers. A. caraya rarely come down from the trees since their food source is entirely in the canopy and their water needs are met by their food. However in especially dry times they will come down to drink water in lakes or supplement their diet with marsh-living herbaceous plants

(Erwin and Mitchell 1986, Welker et al. 1990, Rodrigues and Marinho-Filho 1996)

Although there are reports of Alouatta caraya being imported to the U.S. for use as laboratory animals little else has been reported about their use. Several Black Howler monkeys can be found in zoos. A. caraya are also hunted for meat and fur.

(Muckenhirn 1976, Shoemaker 1979)

Alouatta caraya are threatened by clear-cutting and selective logging since they are heavily reliant on the biodiversity of predominantly primary forests for their diet. Some populations are more threatened than others. According to the Priority Primate Conservation Projects for the Neotropical Region from the Revised Global Action Plan for Primate Conservation, A. caraya, in the Argentine provinces of Formosa, Misiones, Salta and Corrientes are threatened and a high priority for conservation. Hunting pressure on A. caraya ranges from moderate in locations such as San Jose, Bolivia to none in northern Argentina.

(Welker et al. 1990, Mitchell and Erwin 1986, Peres 1997)