Aotus nigriceps Dollman 1909
Creators: name: Russell A. Mittermeier
name: Anthony B. Rylands
name: Don E. Wilson
Publisher: name: Lynx Edicions
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Primates
Aotidae
Aotus
Aotus nigriceps

description: 10. Black-headed Night Monkey Aotus nigriceps
French: Douroucouli de Dollman / German: Schwarzkopf-Nachtaffe / Spanish: Mico nocturno de cabeza negra Other common names: Black-headed Owl Monkey, Night Monkey, Owl Monkey
Taxonomy. Aotus nigriceps Dollman, 1909,
Peru, Chanchamayo, 1000 m.
Populations on either side of the Rio Jurua differ somewhat from each other. Those on the right bank are gray-backed, while those on the left have a reddishbrown back and resemble A. nancymaae. Monotypic.
Distribution. Brazil, S of the Rio Amazonas-Solimoes and W of the Rio TapajosJuruena to the right bank of the Rio Guaporé and the left (N) bank of the Rio Madre de Dios in N Bolivia, also in SE Peru W to the Rio Huallaga and N as far the Rio Cushabatay at about 07° S.
Descriptive notes. Head—body 35-42 cm,tail 35-44 cm; weight ¢.875 g (males) and c.1040 g (females). The Black-headed Night Monkey is a red-necked species, with a diploid chromosome number of 51 in males and 52 in females. It is iron-gray above with a brownish agouti on the dorsum. The underside is orange with white tones, extending to the neck, throat, chin, and sides of the jaw and to the inner surfaces of the wrists and ankles. The cap is black, face stripes are broad, and areas of white on the face are conspicuous. The interscapular whorl is absent.
Habitat. Primary tropical forest, swamp forest, and seasonally flooded forest.
Food and Feeding. Black-headed Night Monkeys eatfruits, which account for ¢.60% of their diet, but they also eat nectar, young leaves and buds,insects, and spiders. In Cocha Cashu Biological Station in Manu National Park and Biosphere Reserve, Peru, they tend to feed more in large trees with larger crowns (more than 11 m in diameter) than sympatric diurnal titi monkeys (similar in size and also living in small monogamous groups) that customarily follow a regular foraging circuit to find small quantities of fruits in smaller crowned trees. Associated with their use of larger-crowned trees, Blackheaded Night Monkeys travel and forage higher up in the forest canopy than the titi monkeys, which spend more than 50% their time in the lower canopy and understory, perhaps due to the titi monkeys susceptibility to predation by diurnal raptors. Diets of Black-headed Night Monkeys and titi monkeys include many bitter or spicy (e.g. Lauraceae) and unripe fruits not generally eaten by other monkeys. Black-headed Night Monkeys forage for insects, especially at dawn and dusk, searching along branches and among foliage. They are adept at catching insects in mid-air and eat moths, beetles, and particularly orthopterans (katydids and grasshoppers of 6-10 cm in length, which call and are active at night and more easily located). Black-headed Night Monkeys are more insectivorous than titi monkeys that supplement the fruit part of their diet more with leaves. When fruits are scarce at the end of the wet season and in the early dry season, Black-headed Night Monkeys eat mostly figs, nectar, and insects. Their consumption of figs is facilitated by the lack of competition from the diurnal primates.
Breeding. In Peru, a seasonal peak in births of Black-headed Night Monkeys occurs between August and February during the rainy season, when fruit is abundant.
Activity patterns. Black-headed Night Monkeys spend ¢.50% of the night active, with maximallevels of activity when the full moon is near the meridian. An activity budget generally consists of 53% foraging, 21% traveling, 22% resting, and 4% agonistic. They are very regular in their activity periods, consistently beginning their day about 13 minutes after sunset and reentering their sleeping sites about 15 minutes before sunrise.
Movements, Home range and Social organization. Social structure of the Black-headed Night Monkey consists of one adult female and one adult male. Group size ranges from two to five, with a mean of four individuals. In a study at Cocha Cashu, homerange size was 7-14 ha with a mean of 9:2 ha (n = = 9 groups). The distance travelled at night averaged 708 m. They traveled twice as far on moonlit nights than on darker nights. Average distance moved on nights with a new moon was 436 m compared to 780 m on a night with a full moon. On dark and rainy nights, travel was slow and curtailed. They traveled farther at dawn and dusk than at other times. They repeatedly used the same routes through the trees indicating that this helped them to navigate in the dark. Principal predators of the Black-headed Night Monkey in the Amazon are diurnal raptors, which explain their propensity to use tree holes for sleeping during the day. Alternate sleeping sites are in very dense foliage, vines, and lianas where they are well hidden. Good sleeping sites appear to be uncommon and are reused frequently; travel during the night is generally circular, returning before sunrise to the sleeping site that they used the previous day. For 60 nights over a year, a group of Black-headed Night Monkeys usedjust five sites, and one of them was used more than 30 times. Both males and females emigrate. A density estimate for Cocha Cashu, Manu National Park and Biosphere Reserve, was 36-40 ind/km?.
Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List. Although the Black-headed Night Monkey is not generally hunted for food, considerable numbers of them were captured and exported to biomedical research laboratories in the 1970s because of their use in research on malaria and in oncology. There is evidence that there is a continuing illegal trade of these monkeys even today. They occur in Manuripe-Heath National Reserve in Bolivia and Manu National Park and Biosphere Reserve in Peru. The Brazilian national parks of Amazonia, Juruena, Pacaas Novos, and Serra do Divisor are within its known range, as are Abufari, Guaporé, and Jaru biological reserves and Rio Acre Ecological Station.
Bibliography. Aquino & Encarnacion (1994a), Bicca-Marques & Garber (2004), Collins (1994), Cornejo & Palacios (2008b), Hershkovitz (1983), Maldonado et al. (2009), Peres (1993), Wright (1978, 1981, 1985, 1986, 1989, 1994).
description: Published as part of Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Aotidae, pp. 414-431 in Handbook of the Mammals of the World – Volume 3 Primates, Barcelona :Lynx Edicions on page 430, DOI: 10.5281/zenodo.5726960