Aotus griseimembra — Details

Grey-legged Night Monkey learn more about names for this taxon

Overview

Brief Summary

Biology

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With unusually small territories for their size, grey-legged night monkeys are relatively sedentary primates, but will defend their range with vigour. Males display and call to intruders, particularly during the breeding seasons, and mark their territory by rubbing a gland at the base of the tail to release a brown, oily and smelly substance. However, although this species is highly monogamous, and exists usually in pairs with up to three dependent young, aggregations of these family units have been seen together, both feeding and sleeping, numbering up to around 30 individuals (3). Each female will only give birth once a year after a gestation of about 130 days. A single infant is born and is lavished with parental care. However, the mother will only have contact with the infant to suckle it. The male is responsible for carrying, defending, playing with and instructing the young, and the mother will actively pull an infant off her and bite it should it try to clamber aboard. The young stay with their parents for two or three years, after which time they become temporarily nomadic as they search for a mate (3). Both males and females urinate on their hands and rub it on branches in order to track down a mate and two individuals will sniff each other for an extended period upon meeting (5). The grey-legged night monkey feeds most on moonlit nights, leaving the sleeping sites shortly after sunset and returning before sunrise (4). It takes fruits, insects and leaves for much of the year, but during July and August when most foods are scarce, it will mainly eat nectar (3). Night monkeys are extremely efficient at snatching insects from leaves, branches (3), and even out of the air with lightening speed (4). They may also feed occasionally on bats, small birds, eggs and lizards. They are rarely preyed upon, but potential predators include cats and large owls, who would likely only manage an infant (3).
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Comprehensive Description

Description

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The grey-legged night monkey belongs to the nocturnal primate genus Aotus, which is also one of the most widespread primate genera in the neotropics. This species is a relatively small monkey, and there are no differences in appearance between males and females. This monkey has a slightly astonished look due to its large eyes, but unlike many nocturnal species, the eyes do not shine in torch light. This is because they do not have a 'tapetum lucidum' – the reflective layer behind the retina of night-time animals that enhances the amount of light they can receive. The lack of this layer betrays the grey-legged night monkey's relatively recent evolutionary split from diurnal monkeys. The coat is thick and two-tone; the tips of the fur are greyish-brown with much lighter bases on the back (3), and pale yellow or orange on the underside (4). The face has white patches above and below the eyes, the cheeks are grey and there is a thin grey stripe down the centre of the forehead. The thick tail is only a little shorter than the body and acts to balance the monkey when walking on all fours along branches. The fingers have true nails and obvious pads to aid grip (3).
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Distribution

Range Description

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Aotus griseimembra is the night monkey of the Río Magdelena and the valleys of the ríos Cauca and São Jorge in northern Colombia (Hernandez-Camacho and Cooper 1976; Defler 2003, 2004). It extends north to the Sierra Nevada de Santa Marta, partly up the Guajira Peninsula and east across the Sierra de Perija to Lake Maracaibo in Venezuela (Hernandez-Camacho and Cooper 1976; Bodini and Pérez-Hernández 1987; Linhares 1998; Defler 2003, 2004).
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Range

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The grey-legged night monkey is known for certain only in northern Colombia (4), roughly between the Rio Sinu and Rio Cauca (2).
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Ecology

Habitat

Habitat and Ecology

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Habitat and Ecology
night monkeys typically occur in primary and secondary forest (including disturbed forest and selectively logged forest), seasonally flooded and terra firma, lowland forest, and submontane and montane (cloud forests) in Colombia and the Andes to 3,200 m above sea level (the specifically montane forms are Aotus lemurinus and Aotus miconax) (Hernández Camacho and Cooper 1976; Aquino and Encarnación 1994a; Defler 2004). Aquino and Encarnación (1994b) reviewed the habitat and forest preferences of the genus.

Night monkeys are nocturnal: they are most active at dawn and dusk. The only exception is Aotus azarae azarae of the Chaco of southern Bolivia, Paraguay and Argentina, which is cathemeral (active during night and day). They are frugivorous; their diet includes fruit, nectar and flower (seasonally important for the A. a. azarae in the Chaco) , leaves, and small animals prey such as insects (Wright 1989; Fernandez-Duque 2007). Aotus azarae has been observed to include a significant portion of leaves in its diet (Ganzhorn and Wright 1994; Wright 1985; Arditi and Placci 1990; Giménez and Fernandez-Duque 2003), as has Aotus zonalis on Barro Colorado Island in an early study by Hladik and Hladik (1969).

They are socially monogamous, living in small groups of an adult pair and offspring of different ages (infant, one or two juveniles and sometimes a subadult. In A. a. azarae a significant number of adults range alone. They may be subadults that have left their natal groups or older adults which have been evicted from their groups by competitors (Fernandez-Duque and Huntington 2002; Fernandez-Duque 2004). Both sexes disperse. Males care for the infants (carry them) (Rotundo et al. 2002, 2005). Lone adults were observed by Villavicencio Galindo (2003) in northern Colombia. Night monkeys are territorial—groups occupy overlapping territories of 5-18 ha (depending on the species and location) (Wright 1978; Fernandez-Duque 2007). Wright (1994) and Fernandez-Duque (2007) review the behaviour and ecology of the genus.

Captive male A. lemurinus reach sexual maturity when 2 years old, and captive female A. vociferans and A. nancymaae first breed when 3-4 years old (Dixson 1983; Fernandez-Duque 2007). In the wild, male A. azarae reach adult weight only when about 4 years old, and age at first reproduction is about 5 years of age (Juárez et al. 2003; Fernandez-Duque 2004). A female A. azaraewas found to breed for the first time at 58 months of age (Fernandez-Duque et al. 2002). Single offspring are the rule. Wright (1985) recorded births between August and February for A. nigriceps in Peru (Manu National Park), and Aquino et al. (1990) indicated a birth season between December and March) for A. nancymaae in north-eastern Peru. In the Argentinean Chaco, A. azarae shows a peak of births between March and June (Fernandez-Duque 2007).

Size:
Adult male weight average 1.0±0.2 kg (n=20), adult female weight 0.923±0.063 kg (n=16) (Dixson 1983)

Systems
  • Terrestrial
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Habitat

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Preferring older, undisturbed forests with high species diversity, the grey-legged night monkey is found only in primary forest and very old secondary forest, but never in young secondary forest (4). Their nest sites are inconspicuous to reduce the threat of predation. They are commonly found in holes in hollow trees, sometimes in cohabitation with bats, as well as in dense vine tangles (3).
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Conservation

Conservation Status

IUCN Red List Assessment

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Red List Category
VU
Vulnerable

Red List Criteria
A2c

Version
3.1

Year Assessed
2008

Assessor/s
Morales-Jiménez, A.L. & Link, A.

Reviewer/s
Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)

Justification
This species is listed as Vulnerable based on the rate of loss of habitat across its range and an inferred population decline at a rate greater than 30% over the past 3 generations (24 years). As forest loss continues this species should be closely monitored.

History
  • 2000
    Endangered
  • 1996
    Endangered
  • 1994
    Vulnerable
    (Groombridge 1994)
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Status

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The grey-legged night monkey is classified as Vulnerable (VU) on the IUCN Red List (1).
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Population

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Population
No information available. Aquino and Encarnación (1994b) reviewed population structure and densities for the genus.

Population Trend
Decreasing
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Threats

Threats

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Major Threats
This night monkey is evidently highly threatened in Colombia, in part due to habitat loss but also because of its capture in the late 1960s and 1970s as an important model for malaria research. Barranquilla was a major port for this commerce. Censuses carried out by Struhsaker et al. (1976) found it to be very scarce, while Green (1978) identified populations in the Sierra San Lucas. This area remains unprotected and could easily be destroyed should the local problems of civil unrest be solved, allowing for colonization.
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Threats

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Being nocturnal not only reduces the threat of natural predation but also significantly protects the grey-legged night monkey from hunting by humans. Whilst many monkey species are killed and captured for sport, food, 'traditional medicine' and to become pets, night monkeys' reclusiveness provides them with some sanctuary. Nonetheless, they are not entirely safe from human interference as they are the best primate model for medical research into malarial vaccines. Many humans are infected with, and die from, malaria each year. This species is particularly suited to malarial research due to its high susceptibility to both forms of malaria-causing Plasmodium parasites, and the similarity of its immune system with that of humans. It is also used to test anti-malarial drugs (6). There is much controversy as to whether it is justifiable to continue taking this threatened species from the wild for the protection of humans, and whilst it can be bred in captivity, individuals are occasionally taken from the wild to prevent inbreeding depression in captive populations (4). Habitat destruction and disturbance are also threats, but the relatively high level of isolation in Colombia's forests affords it some protection (7).
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Management

Conservation Actions

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Conservation Actions
This species is confirmed, or may occur, in several protected areas:

Colombia
Sierra Nevada de Santa Marta National Park (383,000 ha) (in range Defler 2003, 2004)
Iguaque Fauna and Flora Sanctuary (6,750 ha) (Colombia, INDERENA, 1989; Defler 2003, 2004)
Tayrona Natural National Park (15,000 ha) (in range Defler 2003, 2004)
Catatumbo-Barí Natural National Reserve (158,125 ha) (in range Defler 2003, 2004)
Ciénaga Grande de Santa Marta Fauna and Flora Sanctuary (23,000 ha) (in range Defler 2003, 2004)

It is listed on CITES Appendix II.
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Conservation

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The listing of the grey-legged night monkey on Appendix II of the Convention on International Trade in Endangered Species of Fauna and Flora has placed limitations on the numbers allowed to be exported from Colombia to countries conducting medical research. Whilst this has implications on the efficiency and value of medical research into malaria vaccines, it may simply result in the development of malaria research facilities in Colombia, thereby preventing the need for export of grey-legged night monkeys, but continuing their removal from the wild (6) (8). Colombia was the subject of a debt-for-nature swap coordinated by the WWF and The Nature Conservancy, and using funds from the United States Government and the Global Conservation Fund. Millions of U.S. dollars will be released to five conservation sites in Colombia over a 12-year period, in return for the cancellation of a large amount of national debt. This scheme prevents the inevitable loss of funding for environmental projects that occurs as governments slip further into debt, and puts the funds back into environmental enhancement programs, such as the creation of protected areas (9).
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Wikipedia

Gray-handed night monkey

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The gray-handed night monkey (Aotus griseimembra) is a species of night monkey formerly considered a subspecies of Gray-bellied night monkey of the family Aotidae. Its range consists of parts of Colombia and Venezuela.[1][2] The exact classification of the gray-handed night monkey is uncertain. While some authors consider it a subspecies of the gray-bellied night monkey, A. lemurinus, other authors consider it a separate species, A. griseimembra.[1][2][3]

In Colombia, its range consists of the northern portion from the Sinú River (or perhaps further east) to the Venezuelan border, including the Sierra Nevada de Santa Marta and the Magdalena River, Cauca River and Sao Jorge River valleys. In Venezuela, it is found to the west and south of Maracaibo.[1][2]

The gray-handed night monkey is a relatively small monkey, with males weighing approximately 1,009 grams (35.6 oz) and females weighing about 923 grams (32.6 oz).[4] It has short, tight fur. The fur on the back ranges from gray-brown to reddish-brown. The belly is yellowish. The hair on the back of the hands and feet is the color of light coffee with darker hair tips, a key distinguishing feature from other A. lemurinus subspecies.[2]

The gray-handed night monkey is arboreal and nocturnal.[4] It and the other members of the genus Aotus are the only nocturnal monkeys.[5] Laboratory experiments indicated lower levels of activity even in lighting conditions consistent with a full moon.[4] It is found in several types of forest, including secondary forest and coffee plantations, although one study indicated a preference for highly diverse forest.[2] It lives in small groups of between two and six monkeys, most typically two to four, consisting of an adult pair and one infant and several juveniles and/or subadults.[2][4] Groups are territorial, and groups occupy ranges that overlap only slightly.[4] One study found a population density of 1.5 monkeys per square kilometer, while another found a density of 150 monkeys per square kilometer.[2] The latter figure occurred in a forest remnant that had served as a refuge, which may account for the exteremely high density.[4]

In common with other night monkeys, the gray-handed night monkey is one of the few monogamous monkeys.[4] The monogamous pair generally gives birth to a single infant each year, although twins occasionally occur.[2] The gestation period is about 133 days.[4] The father carries the infant from the time it is one or two days old, passing it to the mother for nursing.[2] Average interbirth interval for the mother is 271 days.[4]

The gray-handed night monkey is listed as "vulnerable" by the International Union for Conservation of Nature (IUCN). It is believed to be particularly threatened in Colombia. This is in part due to habitat loss, but also because many were captured in the 1960s and 1970s for malaria research.[1]

References

  1. ^ a b c d e f Morales-Jiménez, A.L. & Link, A. (2008). "Aotus griseimembra". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/1807. Retrieved 19 January 2012. 
  2. ^ a b c d e f g h i Defler, T. (2004). Primates of Colombia. Conservation International. pp. 262–266. ISBN 1-881173-83-6. 
  3. ^ Groves, C. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 140. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100308. 
  4. ^ a b c d e f g h i Fernandez-Duque, E. (2007). "Aotinae". In Campbell, C., Fuentes, A., MacKinnon, K., Panger, M., & Bearder, S.. Primates in Perspective. pp. 139–150. ISBN 978-0-19-517133-4. 
  5. ^ "Primate Fact Sheets - Aotus". http://pin.primate.wisc.edu/factsheets/entry/owl_monkey. Retrieved 2008-12-26. 
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