Aotus vociferans
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 vociferans

description: 6. Spix’s Night Monkey Aotus vociferans
French: Douroucouli de Spix / German: Spix-Nachtaffe / Spanish: Mico nocturno de Spix Other common names: Noisy Night Monkey, Spix's Owl Monkey
Taxonomy. Nyctipithecus vociferans Spix, 1823,
Tabatinga, upper Rio Maranon, Peru.
Censuses along the Rio Nanay and upper Rio Napo and in north-eastern Peru, within the supposed range of A. vociferans, have recorded individuals that differ in appearance and genotype. Monotypic.
Distribution. Widespread in the upper Amazon, extending from NW Brazil (W of rios Negro, upper Uaupés, and Amazonas-Solimoes) into SE Colombia (S of the Rio Tomo in the Orinoco Basin, and perhaps the upper Rio Guyabero), and S into the Ecuadorian Amazon and NE Peru (to the N bank of the rios Maranon and Amazonas, W as far as the Rio Chinchipe); it occurs also S of the Rio Solimoes in a small area on the lower Rio Purus. Ma’s Night Monkey (A. nancymaae) replaces it in a small enclave N of the Rio Maranon between the lower rios Tigre and Pastaza.
Descriptive notes. Head-body 35-45 cm, tail 31-47 cm; weight ¢.708 g (males) and c.698 g (females). Four males from Colombia averaged 697-5 g (range 568-800 g). Spix’s Night Monkeyis a gray-necked species, with a diploid number of chromosomes of 46-48. It 1s brown-toned above, with an off-white underside (having the merest trace of orange); this color extends to wrists, ankles, and the chin. Hands and feet are black. The proximal one-third to one-half of the ventral side ofthe tail is reddish or gray-red; the rest ofthe tail is black. Crown stripes are thick and brownish, with white above the eyes restricted to two small patches grading into the agouti crown. Temporal stripes are nearly always united behind, and the malar stripe ranges from well defined to absent. There is an interscapular whorl of centrifugal hairs. The gular gland is more or less circular. The face is white except for the chin.
Habitat. Tall tropical lowland forest in seasonally flooded forest, swamp forest, and terra firma forest at elevations of 200-900 m. In the Cordillera del Condor of Ecuador and Peru, Spix’s Night Monkey occurs at elevations up to 1550 m. As found for Ma'’s Night Monkey, population densities of Spix’s Night Monkey in upland terra firma forest tend to be lower (0-6-3-5 groups/km?) than in swampy and inundated forest (5-9-12:5 groups/km?)— believed to be a result of reduced availability of tree holes in terra firma forest.
Food and Feeding. Spix’s Night Monkeys primarily eat fruit, which makes up ¢.83% of the diet. They also eat flowers, accounting for up to 17% of the diet at certain times of the year.
Breeding. Records from a captive colony of wild-caught Spix’s Night Monkeys in Iquitos, Peru, provided the following statistics: age atfirst birth averaged about two years, although some individuals began breeding at three years old; the youngest age at conception was 31 months, based on a gestation of 4-5-5 months; interbirth intervals averaged 12-4 months (SD + 6-2 months); ¢.75% of 148 births in the colony occurred between December and May, nearly 60% of them between December and March.
Activity patterns. An 18-month study in the Yasuni National Park, Ecuador, found Spix’s Night Monkeys to be entirely nocturnal. They became active at dusk between 18:00 h and 19:20 h and returned to their sleeping tree between 05:00 h and 06:00 h.
Movements, Home range and Social organization. Spix’s Night Monkeys have a monogamous breeding system. Groups consist of two to five individuals, with an average of three individuals per group. The home range of a group studied in Yasuni National Park was 6-3 ha. The group traveled on average 645 m each night (range 150-1358 m), but travel distances were greater on moonlit nights (average 795 m) than on dark nights with a new moon (average 495 m). The group used only five known sleeping holes during 81 days of study; it used a particular tree for a few days before moving to another. Two of the sleeping sites accounted for 78% of the records. Trees were generally large, but groups also slept in palm crowns on some occasions. A study of night monkeysleeping sites in various localities in northern Peru found most of them in tree holes, sometimes hidden by vines and lianas, and sometimes exposed along banks of creeks, channels or oxbow lakes. They also slept among foliar sheaths in crowns of palms such as buriti (Mauritia flexuosa), Astrocaryum, and Iriartea. Occasionally they shared their holes with other mammals: the Kinkajou (Polos flavus), the Yellow-crowned Brush-tailed Rat (Isothrix bistriata), tree porcupines (Coendou), the Browneared Woolly Opossum (Caluromys lanatus), and bats. Densities of 0-6-12-5 groups/ km? (27-9-38-9 ind/km?) have been reported for seven localities in northern Peru.
Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List. Spix’s Night Monkeys are wide-ranging and relatively abundant in the western Amazon. There are numerous protected areas where it occurs: Jau National Park, Juami-Japura Ecological Reserve, and two large sustainable development reserves— Amana and Mamiraua in Brazil, and national natural parks of Amacayacu, Cahuinari, Serrania de los Picachos, Cueva de los Guacharos, La Paya, Serrania de Chiribiquete, besides Nukak and Puinawai national natural reserves in the Colombian Amazon. In Ecuador, it occurs in Yasuni and Sumaco-Napo Galeras national parks, Cayambe-Coca Ecological Reserve, Cuyabeno Reserve, and Limoncocha Biological Reserve.
Bibliography. Aquino & Encarnacién (1986a, 1988, 1994a), Aquino et al. (1990), Defler (2003b, 2004), Defler & Bueno (2007), Fernandez-Duque (2011a, 2012), Fernandez-Duque, Di Fiore & Carrillo-Bilbao (2008), Ford (1994a, 1994b), Gozalo & Montoya (1990), Hernandez-Camacho & Defler (1985), Hershkovitz (1983), Ma etal. (1985), Maldonado et al. (2009), Montoya et al. (1995), Pieczarka et al. (1992), Puertas et al. (1992, 1995), Tirira (2007), Uribe (1989), Wright (1981, 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 pages 428-429, DOI: 10.5281/zenodo.5726960