Ateles fuscicepsbrown-headed spider monkey

Geographic Range

Ateles fusciceps, the Brown-headed Spider Monkey, can be found from Central America to northern South America (Primate Gallery 2000).


Brown-headed Spider Monkeys are found in the rainforests of Central and South America. The majority of their time is spent in the uppermost branches of trees, foraging for food. Most climates allow them to live year-round in the same area. However, in drier habitats, they must travel up 18 km (10 mi.) each day in search of food(Microsoft Encarta 2000).

Physical Description

Brown-headed Spider Monkeys have long, narrow limbs and a prehensile tail that is used as a fifth limb to swing between branches as they forage for food. Their tail is much longer in length than their body. The tail measures 70 to 85 cm (28 to 34 in.) while the body ranges from 40 to 55 cm (16 to 22 in.). The average weight for both the male and female is approximately 9 kg (20 lbs.). Brown-headed Spider Monkeys can be separated into two subspecies. The subspecies A. f. fusciceps has a brownish-black body with a brown head. A. f. robustus is completely black except for a few white strands of hair on the chin. Their coat is long and shaggy, usually with a lighter underside. A white ring surrounds each eye. Their skull is structured so that they have forward facing eyes which allow them to precisely gauge distances as they swing from tree to tree. The hands and feet of A. fusciceps are adapted for climbing. Brown-headed Spider Monkey species lacks a thumb, which increases the strength of their grip and helps with climbing (Sleeper 1997; Napier 1985).

  • Range mass
    0 to 0 kg
    0.00 to 0.00 lb
  • Average mass
    9 kg
    19.82 lb


Brown-headed spider monkeys indicate that they are prepared to mate through changes in behavior, scents, and visual signals. The estrous cycle is 26 days and females will usually associate with a male for up to three days, with mating lasting between 5 to 10 minutes.

Female Brown-headed Spider Monkeys reach sexual maturity at 51 months. Usually a single offspring is produced and, once born, the young will be cared for only by the mother until weaned at 20 months. On average, Brown-headed Spider Monkeys have a life span of 24 years. (Fleagle 1998; Microsoft Encarta 2000; Sleeper 1997).

  • Average number of offspring
  • Average number of offspring
  • Average gestation period
    227 days
  • Range weaning age
    20 (high) months
  • Average age at sexual or reproductive maturity (female)
    51 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1515 days
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1826 days

Only the female cares for her young, until it is weaned at 20 months. Male brown-headed spider monkeys live in their natal groups for their entire life. Females will disperse at adolescence.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents



Brown-headed spider monkeys are active during the day, sleep at night, and spend most of their time in the trees. These monkeys associate in loose groups of about 20 individuals, but it is rare to find them gathered in one place. Individuals drift between subgroups of varying sizes. They move through the forest using both their hands and feet to swing between trees, and walk in an upright position along branches. Brown-headed Spider Monkeys can leap in excess of 9 meters (30 ft.) from branch to branch (Fleagle 1998; Kinzey 1997; Microsoft Encarta 2000; Napier 1985).

Communication and Perception

Food Habits

Brown-headed Spider Monkeys prefer ripe fruits and leaves, but will eat nuts, seeds, insects, and sometimes eggs. The climate of the rainforests in which they live ensures an abundant supply of food year-round, allowing them to be able to reside in the same area throughout the year (MacDonald 1999; Microsoft Encarta 2000).

  • Animal Foods
  • eggs
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Economic Importance for Humans: Positive

In some areas Brown-headed Spider Monkeys may be hunted for food.

Economic Importance for Humans: Negative

There are no negative effects of Brown-headed Spider Monkeys.

Conservation Status

One of the main reasons Brown-headed Spider Monkeys are declining in numbers is due to deforestation of their habitat. Some of the monkeys are able to survive in areas that have been partially logged, but few can live where rainforests have been completely removed.(Microsoft Encarta 2000).


Bryan Cifranic (author), Fresno City College, Carl Johansson (editor), Fresno City College.



Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate

  1. active during the day, 2. lasting for one day.

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


an animal that mainly eats leaves.


an animal that mainly eats fruit


An animal that eats mainly plants or parts of plants.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


uses touch to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


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Flannery, S. 2000. "Brown-headed Spider Monkey" (On-line). Accessed February 11, 2001 at

Fleagle, J. 1999. Primate Adaptations and Evolution. San Diego: Academic Press.

Hershkovitz, P. 1977. Living New World Monkeys (Platyrrhini) with an Introduction to Primates, Vol 1. Chicago: University of Chicago Press.

Kinzey, W. 1997. Ateles. in New World Primates: Ecology, Evolution, and Behavior. ed. Warren G. Kinzey. New York: Aldine de Gruyter.

MacDonald, D. 1999. The Encyclopedia of Mammals. London: Andromeda Oxford Limited.

Microsoft Encarta Online Encyclopedia, 2000. "Monkey (animal)" (On-line). Accessed February 8, 2001 at

Microsoft Encarta Online Encyclopedia, 2000. "Spider Monkey" (On-line). Accessed February 8, 2001 at

Napier, J. 1985. The Natural History of the Primates. Massachusetts: The MIT Press.

Preston-Mafhan, R. 1992. Primates of the World. New York: Facts on File, Inc..

Primate Gallery, 2000. "Spider Monkeys and Woolly Monkeys" (On-line). Accessed March 8, 2001 at

Rowe, N. 1996. The Pictorial Guide to Living Primates. New York: Pogonias Press.

Sleeper, B. 1997. Primates: The Amazing World of Lemurs, Monkeys, and Apes. San Francisco: Chronicle Books.