Aotus nancymaae
Ma's night monkey

Aotus nancymaae (Ma’s night monkey) can be found in the north central Amazonian neotropics of northern Peru and western Brazil in South America. This species was once thought to belong to the species Aotus trivirgatus, whose range was believed to reach from southern Central America to South America. (Aquino and Encarnacion, 1986a; Aquino and Encarnacion, 1986b; Bales, 1980; Eisenberg and Redford, 1999; Emmons, 1990; Moynihan, 1996)

Although considered habitat generalists (Greenberg, 1999), A. nancymaae are found primarily in lowland tropical rainforests. Aotus nancymaae prefer seasonally flooded forest regions because softer trees provide hollows and hanging shrubbery in which they hide and nest (Aquino and Encarnacion, 1986a, Greenberg, 1999). At night, while active, they occupy the upper levels of the canopy while foraging on fruits and flowers. During the day, they reside within the lower canopy of the forest, remaining inactive. Strongly arboreal, A. nancymaae do not naturally move on the ground. It has only been when individuals were in emergency situations that terrestrial locomotion has been documented (Aquino and Encarnacion, 1986a, Moynihan, 1976). (Aquino and Encarnacion, 1986a; Eisenberg and Redford, 1999; Emmons, 1990; Greenberg, 1999; Moynihan, 1996)

Aotus nancymaae are small monkeys with non prehensile tails. Their pelage is light grey to light brown. Belonging to the “red necked” subdivision of Aotus, these monkeys have reddish orange hair along the sides of the neck and the inner lining of the limbs and tail base (Eisenberg and Redford, 1999, Emmons, 1990). The tail has a black tip and hangs straight down, a distinctive characteristic of all Aotus species (Emmons, 1990). The fur is short, dense and soft (Moynihan, 1996). Aotus nancymaae have characteristically large eyes. Their hands are well developed for grasping, capable of more independent movement than other New World primates (Moynihan, 1976). A post caudal gland is present and enlarged in both sexes; this is used for marking territory. The genitalia of adult A. nancymaae are brightly colored and displayed (Aquino and Encarnacion 1986b). (Aquino and Encarnacion, 1986b; Eisenberg and Redford, 1999; Emmons, 1990; Greenberg, 1999; Moynihan, 1996)

Not enough information can be found on the lifespan of A. nancymaae.

Aotus nancymaae are social. They form small groups of two to five individuals who are all directly related. Competition for resources to create shelter results in strong territoriality within A. nancymaae groups, with individual groups not interacting with one another often. These groups occupy small territories, but the groups are still mobile within the territory (Aquino and Encarnacion, 1986b, Eisenberg and Redford, 1999, Greenberg, 1999). Trees used for foraging are the only areas in which the territories of A. nancymaae overlap. Groups defend their territories through aggressive vocalization and, if the need arises, with violence.

Aotus nancymaae sleep in carefully selected shelters during the day. These shelters are selected using four criteria: protection from predators, including concealment and multiple exits for easy escape; easy access for the individuals; shelter from the elements; and space enough to house the entire group together. These spaces include ready made lodgings such as holes in trees, concavities in branches, thickets, and branches which can be formed into shelters (Aquino and Encarnacion, 1986a). Because of the nocturnal nature of A. nancymaae, these shelters are shared with other organisms in the region with relatively little competition for space (Aquino and Encarnacion, 1986a, Greenberg, 1999, Moynihan, 1976).

During the night, A. nancymaae climb to the upper canopy to forage for food. (Aquino and Encarnacion, 1986b, Einsberg and Redford, 1999). (Aquino and Encarnacion, 1986a; Aquino and Encarnacion, 1986b; Eisenberg and Redford, 1999; Emmons, 1990; Greenberg, 1999; Moynihan, 1996)

Home Range

Groups of A. nancymaae have small home ranges, averaging about 9.2 ha (Eisenberg and Redford, 1999, Greenberg, 1999). This territory is well defined using scent marks (Aquino and Encarnacion, 1986a, Greenberg, 1999). Vocalization are used to show ownership of their territory. Physical force is rarely used to defend territory (Aquino and Encarnacion, 1986b). Slight overlapping of territories occurs commonly, but only includes fruit trees near the edges of territories. Small group sizes need smaller amounts of food, so the sharing of food sources does occur between groups (Aquino and Encarnacion, 1986b, Einsberg and Redford, 1999, Greenberg, 1999). The primary reason for the territoriality of A. nancymaae appears to be for shelters found within a territory. (Aquino and Encarnacion, 1986a; Aquino and Encarnacion, 1986b; Eisenberg and Redford, 1999; Greenberg, 1999)

Aotus nancymaae are very vocal. To remain in constant contact, groups of A. nancymaae constantly use a sequence of squeaks, whistles, and trills. Although this gives the group's position away, it allows for vital information to be passed rapidly through the group (Eisenberg and Redford, 1999, Moynihan, 1976). A slight raise in pitch allows for the communication of danger from predators (Eisenberg and Redford, 1999). Since communication is constant, all individuals in the group are aware of the warning and what it means. (Eisenberg and Redford, 1999; Moynihan, 1996)

These auditory signals are also used for territorial reasons. In defending a territory, individuals, usually juveniles, emit a series of squeaks, whistles and trills for 30-40 minutes. Rival groups respond in kind for longer periods from a distance no closer than 25 feet (Aquino and Encarnacion, 1986b, Einsberg and Redford, 1999, Greenberg, 1999). This exchange is the primary method of showing ownership of a territory. Subadults and solitary adults also emit high pitched squeaking while near or passing through claimed territory. It is believed that this communication is used for the attraction of mates (Greenberg, 1999, Moynihan, 1976). (Aquino and Encarnacion, 1986b; Eisenberg and Redford, 1999; Greenberg, 1999)

Aotus nancymaae use visual perception. Unlike many other nocturnal species, A. nancymaae lack a tapetum locitum, a light catching surface, in the eye. They also retain other diurnal characteristics such as the retention of several types of retinal receptors more useful in seeing higher light intensities. In order to see better at night, A. nancymaae have enlarged eyes allowing for more light to be received. Aotus nancymaae have developed accelerated nerve impulses to and from retinal receptors, allowing them to see more instantaneously. This allows for faster response times through sight, giving A. nancymaae the ability to see insects better and to improve perception while moving. An increased olfactory bulb indicates that smell is also used for perception (Greenberg, 1999). (Greenberg, 1999)

Aotus nancymaae are frugivorous, but, on occasion, feed on insects. Aotus nancymaae feed off of the fruit and the nectar of flowers of trees and insects in the region. They forage near the top of the canopy (Emmons, 1990, Greenberg, 1999, Moynihan, 1976). (Emmons, 1990; Greenberg, 1999; Moynihan, 1996)

The toned down colors of the pelage of A. nancymaae is characteristic of many nocturnal species. This color scheme, along with being active only in the dark, makes it more difficult to see individuals. The large eyes and accelerated nerve signals allow A. nancymaae to see better and faster at night, allowing for better reaction to predator presence (Greenberg, 1999). Aotus nancymaae communicate constantly, allowing for individuals to know where each other are located and for notification of the presence of predators to be passed on quickly throughout the group (Eisenberg and Redford, 1999, Moynihan, 1976). The careful selection of sleeping nests is one more behavioral trait for predator evasion. Part of the criterion for choosing a nest is multiple exits for emergencies. This allows A. nancymaae to quickly evacuate their own nests without being cornered within (Aquino and Enccarnacion, 1986a). (Aquino and Encarnacion, 1986a; Eisenberg and Redford, 1999; Greenberg, 1999; Moynihan, 1996)

There is little information about predation on A. nancymaae. It is speculated that because of their nocturnal nature, strong vocal behavior, and ability to find and defend sufficient shelter, A. nancymaae are a difficult prey to hunt (Aqunia and Encarnacion, 1986a, Greenberg, 1999). Large, arboreal snakes may be their primary predators. (Aquino and Encarnacion, 1986a; Greenberg, 1999)

Aotus nancymaae are frugivores and may help to disperse seeds to a small extent. Living in groups of 2 to 5 individuals and having a population density of 8 to 10 groups per square kilometer, the population density hardly exceeds 20 individuals pre square kilometer. With a low basal metabolic rate, A. nancymaae require little food per individual (Aquino and Encarnacion, 1986a, Eisenberg and Redford, 1999). Aotus nancymaae do not impact food sources substantially because of the combination between this low population density and low food consumption. (Aquino and Encarnacion, 1986a; Eisenberg and Redford, 1999)

Strong defensive behaviors, both nocturnally and diurnally, make A. nancymaae less desirable prey (Bales, 1980, Eisenberg and Redfield, 1999, Moynhan, 1976). Being nocturnal, A. nancymaae share territory with diurnal species with little competition. (Bales, 1980; Eisenberg and Redford, 1999; Moynihan, 1996)

There are no negative impacts of A. nancymaae on humans.

Ma's night monkeys are sometimes used in medical research (Greenberg, 1999).

There is little information on the conservation status of A. nancymaae

Until 1982, the genus Aotus was considered to have only one species, A. trivirgatus. After observing the large variance in reaction to diseases such as malaria amongst individuals of Aotus, it was suggested that the genus consisted of several species (Hershkovitz, 1983). Now, after much molecular research and many field studies, ten species are recognized, including A. nancymaae. However, some researchers recognize only one species still A. trivirgatus (Emmons, 1990). (Eisenberg and Redford, 1999; Emmons, 1990; Hershkovitz, 1983)

Ma's night monkeys are domesticated and associated with human settlements in areas they inhabit.