Mantled howler monkey (Alouatta palliata)

Also known as: common mantled howler, Ecuadorian mantled howling monkey, northern mantled howler, South Pacific blackish howling monkey, southern mantled howler
Synonyms: Alouatta coibensis
Spanish: Aullador De La Costa, Mono Aullador, Mono Congo
GenusAlouatta (1)
SizeMale head-body length: 47 - 63 cm (2)
Female head-body length: 46 - 60 cm (2)
Male tail length: 60 - 70 cm (2)
Female tail length: 55 - 66 cm (2)
Male weight: 4.5 - 9.8 kg (3)
Female weight: 3.1 - 7.6 kg (3)

Classified as Least Concern (LC) on the IUCN Red List (1), and listed under Appendix I of CITES (4). There are five subspecies: the Mexican howler monkey (A. p. mexicana) and the Azuero howler monkey (A. p. trabeata) are classified as Critically Endangered (CR), the Ecuadorian mantled howler monkey (A. p. aequatorialis) and the Coiba Island howler monkey (A. p. coibensis) are classified as Vulnerable (VU), and the golden mantled howler monkey (A. p. palliata) is classified as Least Concern (LC) on the IUCN Red List (1).

Mantled howler monkeys are large, fairly stocky monkeys (5) that are totally black in colour with the exception of a fringe of long golden hairs on the flanks (3). The tail is prehensile and has a naked patch on the underside towards the tip to aid in grasping (5). The face is naked but features a beard that is longer in males than in females (5). When males reach maturity, the scrotum turns white (3). Newborns are golden brown to silvery in colour and weigh 0.4 kg (5). A range of vocalisations are produced, including barks, grunts, and woofs. The howls characteristic of this group of monkeys, and which earn this species its common name, are produced at dawn and dusk, as well as in response to disturbance (5).

Mantled howler monkeys occur throughout the south of Mexico, southern Guatemala extending southwards through Central America reaching the west coast of Colombia and Ecuador (3).

Found in lowland and montane rainforests including both primary and secondary forest (5) up to altitudes of 2000 m (3). They make use of all levels of the canopy, but it seems that the upper third is preferred (3).

The mantled howler monkey is a truly arboreal species, quadrupedally walking and climbing through the canopy or suspending themselves below branches, hanging by the arms and anchoring themselves with their long tail whilst feeding (3). They often cross open areas between forest patches on the ground and are able to swim (3). They are active during the day and sleep on horizontal tree branches at night (3). This species spends much of its time foraging on leaves, fruit and flowers (5). Like all members of the genus Alouatta, the mantled howler monkey has very large salivary glands, which help it to break down the tannins in the leaves before they reach the gut (6).

The mantled howler monkey lives in groups usually numbering between 10 to 20 individuals, in which a distinct social hierarchy exists. There is an alpha male who has priority access to receptive females within the group (3) (5). Females form the stable core within a group, very rarely leaving once established (5).

Breeding occurs throughout the year but births are more common in late December and January (3) (5). A single young is produced after a gestation period of around six months (5) (6). The newborn infant is licked and carried by the mother (3). As it ages, the infant begins to ride around on its mother’s back, grasping the base of her tail with its own (5). For the first four months of life the young monkey will not venture further than two meters away from its mother (3). Sexual maturity is reached at 36 months in females and 42 months in males (5).

Throughout its range, this howler monkey is threatened by forest destruction and fragmentation (5). In areas where forest destruction has been particularly severe, the species often moves into cocoa and coffee plantations (5). Mantled howler monkeys play a key role in the regeneration and health of its rainforest habitats, as they disperse seeds in their dung. Furthermore, their dung is an important resource for a diverse range of dung beetles, which are responsible for the recycling of nutrients from the dung back into the soil (5). The Critically Endangered Mexican subspecies (Alouatta palliata mexicana) has suffered greatly from fragmentation of its habitat. An estimated future decline of 73 - 84% over 30 years has been projected, and habitat loss is ongoing (1). Small, highly isolated populations are unable to disperse naturally; they are at inherent risk of local extinction caused by chance events, such as natural disasters or outbreaks of disease, as well as genetic problems as a result of inbreeding.

The mantled howler monkey is protected from international trade by its listing under Appendix I of the Convention on International Trade in Endangered Species (CITES) (4). It has been estimated that around 1,352 individuals are located within protected areas; however, a further 10,249 occur on unprotected land (5). It has been proposed that new reserves should be established to protect the species, and that translocation programmes should be set up to combat the effects of isolation. In parallel to these measures, it is essential that local environmental education programmes about the importance of the species and its imperilled status should be initiated (5).

To find out more about mantled howler monkey conservation projects, see:

Authenticated (24/10/2005) by Matt Richardson, independent primatologist and writer.

  1. IUCN Red List (January, 2009)
  2. Richardson, M. (2005) Pers. comm.
  3. Broekma, I. (2002) Natural History of the Mantled Howler Monkey (Alouatta palliata) Primates of Panama (March, 2004)
  4. CITES Appendices (March, 2004)
  5. Animal Diversity Web – Mantled howler monkey (March, 2004)
  6. Primate Behaviour – Mantled howler monkey (March, 2004)