Resonant whoops and low-pitched hoots are the most common forms of vocal communication in Aotus. Whoops are usually used in intragroup encounters at the edges of territories and are used with visual displays and scent marking before aggressive interactions. Hoots are usually used in distance communication by unmated males and females and may be involved in mating rituals. Aotus males and females use both urine and skin secretions in scent marking behavior.
Communication Channels: visual ; acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Currently, black-headed night monkeys are considered a species of lesser concern by the IUCN. Their conservation status could change as continued development in the forested areas in which they live affects their habitat.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of black-headed night monkeys on humans.
Black-headed night monkeys are important members of native ecosystems.
Positive Impacts: research and education
Because of their frugivory, black-headed night monkeys are likely to aid in seed dispersal, although little research has been done on their ecosystem roles.
Ecosystem Impact: disperses seeds
Black-headed night monkeys are primarily frugivorous, preferring ripened Ficus fruits. They also opportunistically feed on leaves and flowers as well as moths, beetles, and spiders. However, examinations of fecal matter from A. nigriceps have not yielded significant amounts of leaf fiber or insect matter. This is different from A. vociferans which appears to be more folivorous.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: leaves; fruit; flowers
Primary Diet: herbivore (Frugivore )
Aotus nigriceps (black-headed night monkey) is native to neotropical South America. Black-headed night monkeys are found in an area roughly within the boundaries of 5 to 15° south latitude and 75 to 55° west longitude. This area includes the Amazonian and Madeiran forests in Peru, Brazil, and Columbia and several forest areas found in the Huallaga, Ucayali, Yavari, Purus, and Madre de Dios river basins. It encompasses those areas south of the Amazon River to the Madeira River Basin and the northwestern part of the Tapajoz River Basin. Black-headed night monkeys are a species of "red-necked" or "southern" night monkeys.
Biogeographic Regions: neotropical (Native )
Black-headed night monkeys are usually found in lowland and hillside tropical forest areas. They are usually found in the higher canopy levels of the forest. They choose exclusive sleeping sites in the crooks of branches, especially in trees in the genus Miconia. These trees have large leaves and relatively thick canopy cover. Aotus species generally do not modify their sleeping environments. Other night monkey species, A.vociferans and A. nancymae, have been observed co-occupying sleeping sites with Potos flavus, Bassaricyon gabbi, Coendu bicolor, Tamandua tridactyla, Isothrix bistriatus and bat species.
Range elevation: 0 to 3200 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Not much is known about longevity in Aotus nigriceps in the wild. Individuals in captive populations have been observed to live 15 to 20 years.
Range lifespan
Status: wild: 11 (high) years.
Range lifespan
Status: captivity: 20 (high) years.
Black-headed night monkeys are small primates approximately the same size as a small squirrel. While there are few data concerning the mass of A. nigriceps specifically, Aotus species, both male and female, average 750 g as adults, reaching this size by 14 months of age. Their coats are short and thick. Adult A. nigriceps have dark grey-black agouti pelage on the upper back and forelimbs and orange-tan pelage on the lower back, outer rear legs, and onto the tail. They have three conspicuous black stripes that nearly converge on the forehead. Two of these stripes follow the sides of the face to the maxilla, the central stripe extends to the bridge of the nose. They have white patches over each eye, on the cheeks, and under the mouth. They also have bright orange pelage on the sides of the neck and onto the ventrum, extending from the lower neck, chest and stomach onto the arms, legs and ventral tail. Infants and sub-adults have the same basic coloration. Aotus species have disproportionally large, brown eyes, consistent with their nocturnal habits. They lack a tapetem lucidem. Night monkeys have small external ears that are hidden by their fur. Their digits are long and thin, with straight nails and wide fingertip pads.The second digit of each foot has a curved nail which may be used for grooming. They have an intermembral index of 74, typical of arboreal quadrupeds. The basal metabolic rate is 18 to 24% below that predicted for other 1 kg mammals.
Average mass: 750 g.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
There is little know about predation on Aotus species. Their nocturnality and arboreality helps to protect them from many predators. They rarely leave the trees, only leaving to occasionally cross into other forested areas to forage.
Anti-predator Adaptations: cryptic
Black-headed night monkeys are serially monogamous; mates can be displaced due to violence on the part of a same sex interloper. Males and females form bonds that last until one or the other is displaced. Fruitful mating does not occur until a mated pair has been together for one year. Males have small testicles which might be indicative of monogamy and low mate competition. There seems to be no signal that a female is receptive to mating and mating activity takes place both during and outside of the estrus period. Mating encounters are short in length lasting for 1 to 9 coital thrusts. The breeding period in the wild is between August and February, though Aotus species in captivity have been observed to breed year round.
Mating System: monogamous
Neither males or females seem to give reproductive signals and mating activity is independent of female estrus cycles. Reproductive activity in A. nigriceps usually occurs between August and February and the female produces one infant a year. Twins have been observed only rarely, in 1 out of 169 births. Males and females disperse from their natal range as sub-adults between 26 months and 5 years of age, averaging dispersal at 3 years old. The interbirth interval is from 166 to 419 days. The average weight of a newborn is 90 to 150 g. Full weaning occurs at around weeks 18 to 19. Sexual maturity is at 2 years in males and 3 to 4 years in females.
Breeding interval: Owl monkeys breed once yearly.
Breeding season: The breeding season occurs between August and February.
Range number of offspring: 1 to 2.
Average gestation period: 4 months.
Average weaning age: 19 weeks.
Average time to independence: 18 weeks.
Range age at sexual or reproductive maturity (female): 3 to 4 years.
Range age at sexual or reproductive maturity (male): 2 (low) years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Black-headed night monkey males are primary caregivers for their young. Females nurse their young every 3 hours but then drive the infant away by biting their feet or tail. Males take over care of the infant, except for nursing, after 2 weeks old. At about 8 weeks old, around the time of weaning, the males begin to drive their young away as well. Young sometimes usurp the territories of their parents after independence.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male); pre-independence (Provisioning: Male, Protecting: Male); post-independence association with parents; inherits maternal/paternal territory
The black-headed night monkey (Aotus nigriceps) is a night monkey species from South America. It is found in Brazil, Bolivia and Peru.[2] The A. nigriceps in Peru were notably inhabiting areas that were degraded, and often these areas were disturbed either by human activities or natural occurrences in the ecosystem.[3] A black-headed night monkey is about the same size as a small squirrel. Black-headed night monkeys have small ears that are hidden by their fur. When they become adults they are about 750g and usually are about 14 months old. Black-headed night monkeys have three black stripes that meet on their forehead. These monkeys have white patches by their eyes, cheeks, and under their mouth. Their eyes are very large and brown.[4]
A newborn usually weighs about 90 to 150g. Sexual maturity for males is at 2 years and for females is about 3 or 4 years. They occur in between August and February. A female only gives birth to one infant each year. The males are the primary care givers to the infants. The female starts biting the infants feet or tail about 2 weeks after so they go with the male and about 8 weeks they start to leave them.[4]
Black-headed night monkeys live in small-family groups. Males attack other males and females attack the other females. These attacks can last in between 5 and 30 minutes. The reason why they attack is for territory. Whoever wins the attack gets to keep the territory along with any infants the losing pair have.[4]
Black-headed night monkeys are considered frugivorous. They usually eat leaves, flowers, moths, beetles and spiders.[4]
It is called ausisiti in the Kwaza language of Rondônia, Brazil,[5] and nu’nu’ in the Shawi language of Peru.[6]
A. nigroceps suffers from Plasmodium brasilianum malaria.[7] P. brasilianum was first found in A. nigroceps by Araújo et al. 2013.[7]
The black-headed night monkey (Aotus nigriceps) is a night monkey species from South America. It is found in Brazil, Bolivia and Peru. The A. nigriceps in Peru were notably inhabiting areas that were degraded, and often these areas were disturbed either by human activities or natural occurrences in the ecosystem. A black-headed night monkey is about the same size as a small squirrel. Black-headed night monkeys have small ears that are hidden by their fur. When they become adults they are about 750g and usually are about 14 months old. Black-headed night monkeys have three black stripes that meet on their forehead. These monkeys have white patches by their eyes, cheeks, and under their mouth. Their eyes are very large and brown.
