Colombian night monkey  (Aotus lemurinus)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

The Colombian night monkey belongs to the Aotus genus, the only truly nocturnal monkeys in the world (4). The enormous, closely-set eyes indicate its ability to see in low light levels (5), and this, along with the thick, white eyebrows outlined with black fur result in a very owl-like face (6), hence the alternative name of ‘owl monkey’ (5). The scientific name Aotus means ‘earless’ (7), a name which is slightly misleading as these monkeys do have ears, but has arisen because the small ears are often concealed by fur (6). The thick, woolly fur of the Colombian night monkey is yellowish-grey on the back and pale orange on the belly and it has a long, mostly black tail (6). The Colombian night monkey has a wide repertoire of sounds (7), including soft, low-pitched whoops, grunts and clicks (6).

The Colombian night monkey is endemic to Colombia, Venezula and Ecuador (1).

The Colombian night monkey is typically found in primary and secondary evergreen tropical rainforest (2), from about 1,000 to 3,200 metres above sea level (1).

Feeding at night, the Colombian night monkey avoids potential daytime predators such as cats and birds, while also minimising competition with diurnal foragers (4). During the day it sleeps in dense brush, vines or hollow trees (6), leaving its resting place promptly after sunset to feed. It moves along the branches and between trees and is capable of making huge leaps, three to five metres across gaps in the canopy (4).The Colombian night monkey’s diet consists mainly of fruit, leaves and nectar, but it will also supplement this with small animals such as insects (1).

This species is monogamous and is usually found in small family groups of between two and five individuals, comprising a male and female pair and their offspring (1). A territorial species, each group defends an area of approximately 5 to 18 hectares (1). After a gestation period of 133 days, the female gives birth to a single infant or occasionally twins (3). Unusually for a mammal, the male is the main carer, carrying the infant from the second week after birth until the eighteenth week, when the infant will move independently; the infant will only return to the female for milk. After 2.5 to 3.5 years the young will reach sexual maturity and disperse (8).

The main threat to the Colombian night monkey is habitat loss due to deforestation. It has also been suggested that hybridisation of the Colombian night monkey with other species in the genus Aotus is occurringafter they have been released from captivity outside their natural range. However, little is known about how often this is occurring or any effects it has had on the population (1).

This species is often taken from the wild to be used in medical research. Monkeys in the genus Aotus are used as primate models in the development of anti-malarial compounds and vaccines due to their susceptibility to malaria. Due to declining populations and stricter regulations on wild animal export and import, the availability of this monkey for research is decreasing. As an alternative to taking animals from the wild, the development of breeding programmes is being considered (9). However, both the capture of wild monkeys and the breeding of captive monkeys for medical research are highly controversial issues, due to ethical concerns for the animal’s welfare.

This species is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) which controls the introduction, export and import of any individuals (3). In addition, this species occurs in several protected areas: the Cofán Bermejo Ecological Reserve, Llanganates National Park and Sumaco Napo Galeras National Park in Ecuador, and Tama National Natural Park and Puracé Natural National Park in Colombia (1), which may help protect populations in these areas from the threat of deforestation.

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out about wildlife conservation in Colombia see:

• Conservation International:
  http://www.conservation.org/explore/south_america/colombia
• The Nature Conservancy:
  http://www.nature.org/wherewework/southamerica/colombia