Guatemalan black howler (Alouatta pigra)

Also known as: Black howler monkey, Central American black howler, Guatemalan black howler monkey, Guatemalan howler, Guatemalan howling monkey, Mexican black howler monkey
Synonyms: Alouatta palliata pigra
  
French: Hurleur Du Guatemala
Spanish: Araguato De Guatemala, Mono Aullador Negro, Saraguato, Saraguato Negro
KingdomAnimalia
PhylumChordata
ClassMammalia
OrderPrimates
FamilyAtelidae
GenusAlouatta (1)
SizeMale head-and-body length: 67 - 71 cm (2)
Female head-and-body length: 52 - 64 cm (2)
Male tail length: 60 - 67 cm (2)
Female tail length: 50 - 54 cm (2)
Male weight: c. 11.4 kg (2)
Female weight: c. 6.4 kg (2)

The Guatemalan black howler is classified as Endangered (EN) on the IUCN Red List (1) and listed under Appendix I of CITES (3).

Howlers are among the largest monkeys in the Americas, and the Guatemalan black howler (Alouatta pigra) is among the largest of the genus (4). The Guatemalan black howler has a notably long, silky, dense coat of black fur with traces of brown on the shoulders, cheeks and back (2) (5). A slight crest exists on the crown, and males over the age of four months have a conspicuous white scrotum (2). The arms and legs are long but stout, and the tail is prehensile, lacks hair on its underside, and is used like a fifth limb to grasp branches and anchor the body (5) (6).

Howlers earn their common name from the remarkably loud, rasping calls or howls that are characteristic of the genus (Alouatta), and emitted most elaborately and loudly by adult males (7) (8). These calls can be heard over several kilometres and serve a range of functions, including territorial advertisement, mate attraction and intimidation of rivals or enemies (7).

The Guatemalan black howler is found in Belize, northern Guatemala, south-eastern Mexico and possibly northern Honduras (2) (6). This species can often be observed in the vicinity of Mayan archaeological sites (2).

Th Guatemalan black howler is found in primary and secondary lowland tropical rainforest and semi-deciduous forest (2) (6). One survey suggested riverine and seasonally flooded areas are particularly attractive to this species (9). Although primarily arboreal, individuals living in mangrove swamps have occasionally been seen to swim from one small island to another (2).

Guatemalan black howlers live in stable troops composed of one or two adult males, a few breeding females, and their offspring, with an average group size of between four and six individuals (2) (6). Groups of bachelor males also exist, the members of which will fight resident males for possession of their troop and access to breeding females (6). The territory of each troop ranges between 3 and 25 hectares, depending upon the size of the group (10). Single offspring are usual, born after a gestation period of 180 – 194 days (2).

Leaves and fruit form the bulk of the diet, although flowers and insects may also be eaten. Like other members of its genus, the Guatemalan black howler has large salivary glands that help to break down the tannins in the leaves they eat (6). This monkey is mainly active in the morning and evening, but also remains busy throughout the day (5).

The Guatemalan black howler is threatened throughout most of its range from hunting and habitat destruction (10). Suitable forest habitat has rapidly been lost and fragmented through conversion to pasture and agricultural lands, and to logging operations (8). If such patterns continue, the population size of this species is projected to decline by around 74% over three generations (30 years) (1).

The Guatemalan black howler is known to occur in six protected areas: Cockscomb Basin Wildlife Sanctuary, Guanacaste and Monkey Bay National Parks (Belize); Rio Dulce and Tikal National Parks (Guatemala); and Palenque National Park (Mexico) (2).

Additionally, a community-based conservation organization in Belize called the Community Baboon Sanctuary (this species is called 'baboon' in the local Creole dialect) has protected land along the Belize River, ensuring that this howler’s food trees are not destroyed to make way for pasture (10). Over 200 private landowners here in seven villages, stretching over 20 square miles, have voluntarily pledged to conserve their land for the protection of the Guatemalan black howler, many of which will consequently benefit from ecotourism. Indeed, one of the main aims of the Community Baboon Sanctuary is to help address habitat destruction by promoting sustainable tourism as an attractive alternative to destructive land management practices. At the same time, the Sanctuary conducts conservation research and educates the local community and visitors about the importance of biodiversity (8).

Other conservation measures implemented by the Sanctuary include creative initiatives like building bridges made of rope and sticks that allow the monkeys to pass between gaps in the forest, and relocating a number of individuals to the Cockscomb Basin Wildlife Sanctuary (8). If similar efforts were made in Mexico and Guatemala, and ecotourism was promoted as a viable means of profiting from protected forest habitats, the Guatemalan black howler would perhaps have a much higher chance of long-term survival.

For more information on the Guatemalan black howler see:

Primate Behaviour:
http://www.americazoo.com/goto/index/mammals/95.htm

For more information on the Community Baboon Sanctuary see:

Community Baboon Sanctuary:
http://www.howlermonkeys.org/

Authenticated (19/06/2006) by Matt Richardson, independent primatologist and writer.

  1. IUCN Red List (January, 2009)
    http://www.iucnredlist.org
  2. Richardson, M. (2006) Living Primates of the World: an Illustrated Taxonomy. In press, Unknown.
  3. CITES (January, 2006)
    http://www.cites.org
  4. Richardson, M. (2006) Pers. comm.
  5. American Zoo (April, 2006)
    http://www.americazoo.com/goto/index/mammals/95.htm
  6. Primate Behaviour (April, 2006)
    http://members.tripod.com/uakari/alouatta_pigra.html
  7. Treves, A. and Brandon, K. (2005) Tourism impacts on the behavior of black howler monkeys (Alouatta pigra) at Lamanai, Belize. In: Paterson, J.D. (Ed) Commensalism and Conflict: The primate-human interface. University of Oklahoma, Tulsa. Available at:
    http://www.coex-wildlife.org/publications.htm
  8. Community Baboon Sanctuary (April, 2006)
    http://www.howlermonkeys.org/
  9. Silver, S.C., Ostro, L.E.T., Yeager, C.P. and Horwich, R. (1998) Feeding Ecology of the Black Howler Monkey (Alouatta pigra) in Northern Belize. American Journal of Primatology, 45: 263 - 279. Available at:
    http://www.communityconservation.org/publications/feedeco98.pdf
  10. The Belize Zoo (April, 2006)
    http://www.belizezoo.org/zoo/zoo/mammals/how/how1.html