Atelidaehowler and prehensile tailed monkeys


Prehensile tailed monkeys are the largest of the New World Monkeys. There are 24 species in the family Atelidae, including 10 species of howler monkeys (Alouatta), 7 spider monkeys (Ateles), 2 muriquis (Brachyteles), 4 woolly monkeys (Lagothrix), and 1 yellow-tailed woolly monkey (Oreonax). All atelids have prehensile tails that are sensitive and used for grasping objects. (Groves, 2001; Nowak, 1991; Wilson and Reeder, 2005)

Geographic Range

Prehensile tailed monkeys are found in Central and South America. The howler monkeys (Alouatta) are the most widespread New World monkey genus, occurring from southern Mexico to northern Argentina. Spider monkeys (Ateles) are also fairly widespread, occurring from southern Mexico through the Amazon basin. Woolly monkeys (Lagothrix) are found only in the Amazon. Muriquis (Brachyteles) are restricted to the southeastern Atlantic rainforest of Brazil and yellow-tailed woolly monkeys (Oreonax) are found only in the cloud forests of a portion of the Peruvian Andes. (Nowak, 1991; Strier, 2004)


All prehensile tailed monkeys are highly arboreal and found exclusively in forests. Some species, such as woolly monkeys (Lagothrix) and some spider monkeys (Ateles) are found only in primary forests but most species also occur in secondary or disturbed forests. (Nowak, 1991; Strier, 2004)

Physical Description

Prehensile tailed monkeys are the largest of the New World monkeys. Species range from 382 to 686 mm head and body length in the Atelinae and from 559 to 915 mm head and body length in the howler monkeys (Alouattinae). Atelinae tail length ranges from 508 to 890 mm and weight from 5.5 to 15 kg. Alouattinae tail length ranges from 585 to 915 mm and weight from 4 to 12 kg. Males are substantially larger than females in howler monkeys (Alouatta) and woolly monkeys (Lagothrix), sexes are similar in size in other genera. Dental formula is I 2/2; C1/1; P 3/3; M 3/3. (Nowak, 1991)

Prehensile tailed monkeys are from pale buff or gray (Brachyteles) to dark black (Ateles) in pelage color. Males and females differ in color in some species of howler monkeys. Prehensile tailed monkeys tend to have long limbs, fingers, and tails. This is especially pronounced in spider monkeys and muriquis, where it is associated with brachiation and suspensory locomotion. Woolly monkeys and howler monkeys have more compact bodies and are not as fast and agile as are spider monkeys and muriquis. Female Ateles and Brachyteles have pendulous clitorises. Howler monkeys have a greatly enlarged hyoid bone which is used to help project their very loud roaring vocalizations. They also have an enlarged hindgut. (Nowak, 1991; Strier, 2004)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • sexes colored or patterned differently


Female prehensile tailed monkeys mate with multiple male partners. Depending on the composition of social groups, dominant males may effectively monopolize matings with group females. (Nowak, 1991; Strier, 2004)

Births generally occur in dry seasons, when preferred foods are scarce. Conception and weaning usually occurs during wet seasons, when food is plentiful. Gestation length is from 6 to 7.2 months and usually 1 young is born, twins are rare. Interbirth intervals are from 2 years in Alouatta to 3 years in the ateline genera. Females become sexually mature at from 4 (Alouatta) to 9 years old (Brachyteles). (Nowak, 1991; Strier, 2004)

There is no evidence of male parental care in prehensile tailed monkeys. Females care for and nurse their young. (Nowak, 1991; Strier, 2004)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female


A captive woolly monkey lived for nearly 25 years, a captive spider monkey lived for 48 years, and a captive howler monkey for more than 23 years. Wild howler monkeys live for over 20 years, with an average of 16 years. (Nowak, 1991)


Prehensile tailed monkeys are diurnal. They spend a large part of every day resting, up to 70% of their time. They are exclusively arboreal, although some species have occasionally been observed descending to the ground to drink, forage, and play. Spider monkeys and muriquis are superb brachiators and exceptionally agile when locomoting in forest canopies. (Strier, 2004)

Prehensile tailed monkeys live in multi-male, multi-female social groups of 3 to 100 individuals. Woolly monkeys often occur in groups of 30 to 40 and spider monkeys in groups of 2 to 30. Howler monkeys often occur in smaller groups of 3 to 19. In ateline genera males are philopatric and females disperse from their natal groups. Both males and females disperse from their natal groups in howler monkeys. Groups don't defend territories, although inter-group conflict can sometimes be intense in howler groups. Home range sizes range from 10 hectares in Alouatta to over 900 hectares in Lagothrix and Brachyteles. (Nowak, 1991; Strier, 2004)

Communication and Perception

All species use vocalizations to communicate, but howler monkeys are best known for their powerful, long-distance roars. Male howler monkeys roar most often at the boundaries of their home ranges and can be heard by humans up to 2 kilometers away. Some species are also known to apply urine to their hands and feet, depositing scent as they move. (Nowak, 1991; Strier, 2004)

Food Habits

Prehensile tailed monkeys are primarily frugivorous, although they also consume variable quantities of leaves, flowers, nectar, plant gums, new shoots, and insects. Howler monkeys (Alouatta) are the most folivorous of the prehensile tailed monkeys. Diet varies geographically and seasonally, though, with more fruits consumed when available and leaves becoming a more important part of the diet in parts of the year where fruits are less available and in disturbed forests. Prehensile tailed monkeys use their tails extensively. Individuals often feed while suspended, hanging from their tail. (Nowak, 1991; Strier, 2004)


There are few reported predators of prehensile tailed monkeys. They are at risk of predation from arboreal predators, such as large snakes and felids. Large, diurnal raptors may also take these monkeys from forest canopies.

Ecosystem Roles

Prehensile tailed monkeys aid in the dispersal of forest trees through their frugivory. (Nowak, 1991; Strier, 2004)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Prehensile tailed monkeys are important in many Central and South American cultures. They are featured in myths and legends and some body parts are thought to have special powers. Their large body size makes many prehensile tailed monkeys a desirable source of meat and the docility of some species makes them popular as pets. Prehensile tailed monkeys are fascinating and ubiquitous components of neotropical forests, making them important for ecotourism. (Nowak, 1991; Strier, 2004)

Economic Importance for Humans: Negative

Although large and frugivorous, none of the atelids are considered agricultural pests. (Strier, 2004)

Conservation Status

Both Brachyteles species, Oreonax flavicauda, 3 species of Alouatta, and 2 subspecies of Ateles geoffroyi are on Appendix I of CITES. Alouatta pigra, Ateles marginatus, and Brachyteles arachnoides are considered endangered by the IUCN. Ateles hybridus, Brachyteles hypoxanthus, and Oreonax flavicauda are considered critically endangered. The muriquis (Brachyteles) are the only New World monkeys restricted to the Brazilian Atlantic rainforest, making them especially vulnerable. Brachyteles hypoxanthus populations are estimated at around 500 individuals. Oreonax flavicauda populations, restricted to a small area of the Peruvian Andes, are estimated at 200 individuals. (International Union for the Conservation of Nature, 2007; Nowak, 1991; Strier, 2004)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

Atelids are known from Pleistocene fossil deposits. (Strier, 2004)


Tanya Dewey (author), Animal Diversity Web.



living in the southern part of the New World. In other words, Central and South America.

World Map


uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.


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


to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

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

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.


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.


A substance that provides both nutrients and energy to a living thing.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


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.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


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.


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season


remains in the same area


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


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight 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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