Overview

Brief Summary

Biology

The variegated spider monkey has a complex social system, living in multi-male, multi-female “fission-fusion communities” of 3 to 22 individuals. These groups break up into smaller subgroups to forage, and have a home range of around 260 to 390 hectares. A wide variety of calls are used, including 'ts chookis', whoops and wails to locate other subgroups. When two subgroups reunite there is an excited greeting display, which involves vocalizing, chasing, hugging with tails entwined, and sniffing of the sternal glands. This diurnal species is active during the day, foraging primarily for ripe fruit, although also supplementing the diet with decaying wood, leaves and flowers. If potential predators are sighted, individuals shake branches at them to scare them off (2). The variegated spider monkey gives birth to single young, after a gestation of 225 days (2). Baby spider monkeys tend to cling to their mother's belly for around the first four months of life, after which they climb to her back, eventually developing enough independence to travel on their own (3). Like other spider monkeys, this species is characterised by a slow reproductive rate, with females typically giving birth to single offspring only once every three to four years (4).
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Description

Exceptionally long, spindly limbs have inspired the common name of spider monkeys (Atelidae), together with their long prehensile tail that acts almost like a fifth limb. Indeed, their tails have highly flexible hairless tips with skin grooves that help to grip, an adaptation to the spider monkey's strictly arboreal lifestyle. Spider monkeys also possess narrow and thumbless, hook-like hands, with fingers that are elongate and curved (3). The variegated spider monkey ranges in colouration from a light brown to a rich mahogany on the upper surfaces of its body, limbs and head (2). By contrast, the abdomen, inner sides of the limbs and underside of the tail are a paler, buff colour, and a conspicuous white triangular patch marks the forehead (2). While normally light brown, some individuals have been observed with eyes that are a striking pale blue (2).
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Distribution

Range Description

In Colombia, Ateles hybridus hybridus is found from the right bank of the Ro Magdalena in the Departments of Magdalena, Csar (northward to the southern slopes of the Sierra Nevada de Santa Marta), the south-western portions of Guajira in the northernmost parts of the Serrana de Perij, and in the middle Ro Magdalena valley at least to the Departments of Caldas and Cundinamarca. There are also two populations of this subspecies on the slopes of the Cordillera Oriental of the Andes on the Venezuelan border: one population is found in the Ro Catatumbo watershed in the Department of Norte de Santander and the other population is found in the north-east piedmont forest of the Department of Arauca (Hernndez-Camacho and Cooper 1976; Defler 2003, 2004).

The subspecies has a disrupted distribution in Venezuela (Mondolfi and Eisenberg 1979). It is located in the north, along the south-eastern part of the Central Mountain Range (Cordillera de la Costa) in the state of Miranda, and probably the state of Vargas. It is also located on both sides of the Venezuelan Andean Mountains (states of Zulia, Tchira, Mrida, Trujillo, Portuguesa, Apure and Barinas). In its eastern part, this primate is distributed on the piedmont forest and in the highly threatened lowland forests of San Camilo and Ticoporo. On the western side, it is also distributed in the piedmont of the Andes throughout the lowland areas of southern Lake Maracaibo to the Perij Mountains (Sierra de Perij) along the border with Colombia (Bodini and Prez-Hernndez 1987; Linares 1998; Cordero-Rodrguez and Biord 2001; Portillo and Velsquez 2006; Duque 2007; B. Urbani, unpubl.).

In Colombia, Ateles hybridus brunneus is found between the lower Cauca and Magdalena Rivers in the Department of Bolvar, Antioquia and Caldas. This population has sometimes been included with A. h. hybridus, but is here considered distinct.
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Brown spider monkeys, Ateles hybridus, are restricted to subtropical and tropical moist lowlands in Venezuela and Colombia. There are two recognized subspecies of A. hybridus, Ateles hybridus hybridus and Ateles hybridus brunneus. The former occurs in both Colombia and Venezuela, inhabiting forests from the right bank of the Río Magdalena to areas extending into western parts of Venezuela. Ateles hybridus brunneus can only be found in Colombia, ranging between the lower Ríos Cauca and Magdalena in the Departments of Bolívar, Antioquia, and Caldas.

Biogeographic Regions: neotropical (Native )

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Range

Found in northern Colombia and north-western Venezuela (2). Whilst the nominate subspecies, the hybrid spider monkey (A. h. hybridus), occurs from the right bank of the Rio Magdalena in Colombia into western Venezuela, the brown spider monkey (A. h. brunneus) subspecies is restricted to Colombia, ranging between the lower Rios Cauca and Magdalena (4).
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Physical Description

Morphology

The appearance of Ateles hybridus is similar to other species of spider monkeys and, as their common name indicates, spider monkeys have exceptionally long, slender limbs. Their forelimbs are longer than their hindlimbs and their intermembral index is approximately 105. They also have a long, thin, prehensile tail, which acts almost like a fifth limb. These features enable them to be highly suspensory and allow them to easily forage and travel in the high canopy. The length of the tail is around 75 cm and is highly flexible and distally hairless, with ridged skin for a better grip. The hands are hook-like, with four elongated, curved, fingers. The thumb is reduced, which facilitates swinging and gripping branches and is an adaptation to their strictly arboreal lifestyle. Spider monkeys are the biggest of all the New World primates, an adult male brown spider monkey weighs between 7.9 and 9.1 kg and an adult female weighs between 7.5 and 9 kg. The average body length for adult individuals is around 50 cm. Their coloration ranges from light brown to dark on upper parts including the head. The inner side of the legs, arms and tail are a lighter, more buff color. Another distinguishing characteristic of this species is the white triangular forehead patch but not all individuals possess this conspicuous feature. Some individuals also have pale blue eyes, but usually they are light brown.

Range mass: 7.5 to 10.5 kg.

Average mass: 8.5 kg.

Range length: 45 to 50 cm.

Average length: 47 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

  • Ankel-Simons, F. 1999. Primate Anatomy: An Introduction. 2nd Ed. San Diego: Academic Press.
  • Fleagle, J. 1999. Primate Adaptation and Evolution 2nd Ed.. San Diego: Academic Press.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
In Venezuela, Ateles hybridus hybridus inhabits mainly the high and lowland primary evergreen rainforests from 20 to 700 m asl.

Spider monkeys travel and forage in the upper levels of the forest. They spend much time in the canopy and also use the middle and lower strata but are rarely seen in the understorey. In accordance with their use of the highest levels of the forest, they are highly suspensory. When travelling they spend more time hanging from branches, moving by brachiation and arm swinging, and climbing than they do walking or running on all fours. They are highly frugivorous and feed largely on the mature, soft parts of a very wide variety of fruits, which comprise 83% of their diet and are found mainly in the emergent trees and upper part of the forest canopy (Van Roosmalen and Klein 1988). They also eat young leaves and flowers (both especially at times of fruit shortage during the beginning of the dry season), and besides such as young seeds, floral buds, pseudobulbs, aerial roots, bark, decaying wood, and honey, and very occasionally small insects such as termites and caterpillars. They play a significant role as seed dispersers. Van Roosmalen (1985; Van Roosmalen and Klein 1988) found that A. paniscus was dispersing the seeds of at least 138 species (93.5% of all fruits species used) through their ingestion and subsequent defecation (endozoochory). A further 10 species were being dispersed by the monkeys carrying them off some distance from the tree before dropping them (exozoochory). In only 23 species were the seeds being ruined or eaten (seed predation).

Spider monkeys live in groups of up to 20-30 individuals (for review see Van Roosmalen and Klein 1988). However, they are very rarely all seen together, and nearly always to be found travelling, feeding and resting small in groups of varying size and composition, the only persistent association being that of a mother and her offspring (McFarland Symington 1990). Group members will also travel on their own. Each female in the group has a core area of the groups home range which she uses most. Klein and Klein (1976, 1977) estimated 259-388 ha ranges with 20-30% overlap for A. belzebuth in La Macarena National Park, Colombia. Ateles are rarely seen in association with other primates and mostly they are occasional and ephemeral, resulting from the simultaneous occupation of fruiting trees.

Six estimated birth dates given by Klein (1971) for the closely related A. belzebuth, were spread throughout the year (December, January, April, September, October and November). Spider monkeys apparently reach sexual maturity at 4-5 years of age (Klein 1971; Eisenberg 1973, 1976). They give birth to single offspring after a long gestation period of 226-232 days, with a minimum theoretical interbirth interval in captivity of 17.5 months, but in the wild probably as long as 28-30 months (Eisenberg 1973, 1976).

Congdon (1996) provided a brief remark on the behaviour of these monkeys at the Reserva Forestal Caparo, and Duque (2007) provided a list of potential feeding trees for Ateles hybridus hybridus in the El vila National Park (however, this primate species was not observed at the time of Duques survey). Late maturation and long inter-birth intervals makes it difficult for them to recover from hunting and other threats.

Size
Adult male weight 7.9-8.6 kg (mean 8.25 kg, n=2) (see Di Fiore and Campbell 2007
Adult female weight 7.5-10.5 kg (mean 9.1 kg, n=7) (see Di Fiore and Campbell 2007).

Systems
  • Terrestrial
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Brown spider monkeys are arboreal and mainly found in high and lowland primary evergreen rainforest from 20 to 700 m elevation. They spend most of their time traveling and foraging in the high canopy, but they also use the middle and lower strata to a lesser extent. They rarely descend to the forest floor except for drinking water or eating soil. Brown spider monkeys are habitat specialists and prefer undisturbed old forests (primary forests) and rarely inhabit disturbed forests with less complete canopy (secondary forests). Primary forests have tall mature trees, a continuous canopy, an understory with little underbrush and significant bigger and more abundant fruiting trees than secondary forests have. One reason for their habitat choice is that their diet primarily consists of fruit.

Range elevation: 20 to 700 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: rainforest

  • Chapman, C., D. Onderdonk. 1998. Forests without primates: Primate/Plant codependency. American Journal of Primatology, 45: 127-141.
  • Morales Jiménez, A. 2007. "Action Plan of the spider monkeys Ateles hybridus and Ateles fusciceps in Colombia" (On-line pdf). Accessed January 12, 2009 at http://www.fundacionbiodiversa.org/pdf/Ateles/Atelesactionplanweb.pdf.
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Primary rainforest is inhabited, as well as riverine, marsh and semi-deciduous forest. An arboreal species that prefers old, tall trees, where it usually confines itself to the upper levels of the canopy (2).
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Trophic Strategy

Brown spider monkeys are highly frugivorous and feed on a wide variety of fruits all year round. They specialize on ripe fruit, which comprises approximately 83% of their diet. A large part of their fruit intake consists of lipid rich fruits in the families Arecaceae, Lauraceae, Meliaceae and Myristicaceae. However, their dietary composition is dependent on seasonal variation in fruit abundance. When fruits are less abundant during dryer seasons they complement their diet with young leaves and flowers, young seeds, bark, honey, decaying wood, and sometimes even termites and caterpillars. Brown spider monkeys forage mainly in emergent trees and upper part of the forest canopy and rely heavily on vision to recognize food items, but also use olfactory, gustatory, and tactile cues to a lesser extent. Figs of different species are a very important food resource, which spider monkeys feed on all year around. They have also been observed eating soil and clay. Several hypotheses to why this might be have been put forward, from the importance of the high mineral content in the soil, to the need for phosphorus and the need to keep an even pH- balance in their digestive system. Spider monkeys also descend to the forest floor to drink water at so called salado sites, and it is hypothesized that their water consumption is a consequence of their high intake of lipid rich fruits. Interspecific feeding competition occurs between spider monkeys and other frugivorous primates, for example woolly monkeys, howler monkeys, squirrel monkeys, and other New World monkeys.

Animal Foods: insects

Plant Foods: leaves; roots and tubers; wood, bark, or stems; fruit; nectar; pollen; flowers

Primary Diet: herbivore (Frugivore )

  • Cowlishaw, G., R. Dunbar. 2000. Primate Conservation Biology. Chicago: The University of Chicago Press.
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Associations

Studies of seed dispersal by spider monkeys have shown that they play an important role in the maintenance of neotropical rain forest diversity, both through endozoochory and exozoochory. Endozoochory is when the animal disperses the fruit's seeds within the body of the animal, as they swallow the seeds and they pass through the animal's digestive system. Exozoochory is when the animal disperses seeds by carrying them off from the tree to another location and drop them. Link and Di Fiore (2006) found that Ateles belzebuth swallowed 98% of the seeds from the approximately 152 different plant species that the monkeys fed on. They also found that monkeys appear to be particularly important dispersers for plants producing large seeded fruits or those protected by thick husks, many of which other frugivorous species cannot eat. An individual spider monkey dispersed a minimum of 195,000 seeds per year which were bigger than 1 mm in diameter and 35,000 seeds bigger than 3 mm in diameter. The longest distance seeds were moved was 1.2 km, though the average distance was 443 m from the parental source. The results of Link and Di Fiore (2006) and Stevenson and Aldana (2008) show that spider monkeys play a significant role as seed dispersers and that a population decline could have a big and direct impact on forest dynamics, particularly if other disperser species cannot compensate for their lost ecological services. Furthermore, it is possible that their fission–fusion social structure and ranging behavior also influence their pattern of seed dispersal. The fact that they split up in subgroups while foraging could generate a more scattered distribution of defecated seed across the habitat, compared with species that ranges in more cohesive groups. This ranging pattern of spider monkeys could in turn have positive effects on growing rates and survival of the seeds.

Ecosystem Impact: disperses seeds

Mutualist Species:

  • Arecaceae
  • Lauraceae
  • Meliaceae
  • Myristicaceae

  • Link, A., A. Di Fiore. 2006. Seed dispersal by spider monkeys and its importance in the maintenance of neotropical rain-forest diversity. Journal of Tropical Ecology, 22: 235–246.
  • Stevenson, P., A. Aldana. 2008. Potential Effects of Ateline Extinction and Forest Fragmentation on Plant Diversity and Composition in the Western Orinoco Basin, Colombia.. International Journal of Primatology, 29: 365–377.
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Because of the large body size of Ateles hybridus, the only significant potential predators on adult individuals are thought to be jaguars and pumas. Matsuda and Izawa (2008) report predation attempts by a jaguar (Panthera onca) and a puma (Puma concolor) on an adult female of the spider monkey species Ateles belzebuth. However, babies and juveniles are susceptible to predators like harpy eagles (Harpia harpyja), crested eagles (Morphnus guianensis), and smaller carnivores.

Poaching also poses a major threat to Ateles hybridus, they are subject to both subsistence and commercial hunting. They are primarily hunted for meat, but hunting for the pet trade is not unusual. In pet trade situations the female is killed and the baby is kept and sold.

Known Predators:

  • jaguars (Panthera onca)
  • mountain lions (Felis concolor)
  • harpy eagles (Harpia harpyja)
  • crested eagles (Morphnus guianensis)

  • Matsuda, I., K. Izawa. 2008. Predation of wild spider monkeys at La Macarena, Colombia. Primates, 49: 65-68.
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Life History and Behavior

Behavior

Brown spider monkeys frequently use a wide variety of calls to keep contact with each other and to locate other subgroups. They use so called whinnies, i.e. loud calls mostly, which bring information about location and identity of the emitter, but they also use ‘ts chookis’, whoops, wails and screams. The latter can be heard over long distances. Alarm calls are also used when predators are nearby.  Tactile communication occurs in the form of grooming. This is an infrequent behavior in spider monkeys and some claim that it is due to the absent thumb. Ahumada (1992) found that Ateles geoffroyi individuals allocated only 2.5% of their daily activity to grooming, mostly adult females groom their offspring or other juveniles, but male-male grooming occurs as well.  Brown spider monkeys have good eye sight and excellent color vision, which is important for detecting and selecting ripe fruits from unripe ones, but is also used for the detecting predators, as well as for communicating with conspecifics. Visual signals such as head shaking, arm and chest scratching as well as tooth exposure are used in antagonistic and threat situations.  Olfactory behaviors are used in sexual contexts, in which chest-rubbing and pectoral gland sniffing occur. Female spider monkeys also use their over-sized clitoris to deposit drops of urine as scent marks.

Communication Channels: visual ; tactile ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; tactile ; acoustic ; chemical

  • Ahumada, J. 1992. Grooming Behavior of Spider Monkeys (Ateles geoffroyi) on Barro Colorado Island, Panama. International Journal of Primatology, 13: 33-49.
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Life Expectancy

The average life span for spider monkeys is approximately 27 years in the wild. In captivity, on the other hand, they can live to be 10 years old or more.

Average lifespan

Status: wild:
27 years.

Range lifespan

Status: captivity:
40 (high) years.

Average lifespan

Status: wild:
27 years.

Typical lifespan

Status: captivity:
40 (high) years.

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Reproduction

The mating system of brown spider monkeys is not well studied, but is most likely similar to that of other members of Atelinae which are polygynandrous, where each individual mates with multiple partners. All copulations are initiated by the female, which indicates a high level of female mate choice and might lead to reduced aggression in males. Females in this genus copulate with many males over a period of time; this might be a female strategy to prevent infanticide by causing paternity confusion. However, intragroup infanticide by other males has been observed, although not reported for this particular species. Mating is not seasonal and no precopulatory rituals have been observed in spider monkeys.

Mating System: polygynandrous (promiscuous)

Similar to the other species of spider monkeys, Ateles hybridus is characterised by a slow reproductive rate, with females usually giving birth to a single offspring every 3 to 4 years. Although not reported for this particular species, intragroup infanticide by males has been observed in other spider monkey species which shortens the interbirth interval. In captivity the birth interval of brown spider monkeys can be reduced to a minimum of 1.5 years and they do not show seasonality in their births. Wild populations, however, show a low grade of seasonality, with a higher birth rate at the beginning of the rainy season, May to July, when fruits are more abundant. The species typically reaches sexual maturity at 4 to 5 years of age and females give birth to their first infant at an age of 7 to 8 years.

Breeding interval: Female brown spider monkeys give birth to a single offspring every 3 to 4 years.

Breeding season: Wild populations, but not captive, show a low grade of seasonality, with a higher birth rate in the beginning of the rainy season, May to July.

Range number of offspring: 1 to 1.

Range gestation period: 226 to 232 days.

Average gestation period: 230 days.

Range weaning age: 12 to 20 months.

Average weaning age: 15 months.

Average time to independence: 18 months.

Average age at sexual or reproductive maturity (female): 4 to 5 years.

Average age at sexual or reproductive maturity (male): 4 to 5 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous

The gestation period is approximately 226 to 232 days. When offspring are born they cling to their mother’s belly the first couple of months, and then climb over to her back. Young lactate at least one year. In captive spider monkeys, however, lactation has been seen up to twenty months. Females provide the major part of the parental care and very strong social bonds are formed between females and their offspring. During the dependent period, which is approximately 18 months, the offspring gets protection as well as an extended period of learning, where the offspring learns everything from social to foraging behaviors.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
A2cd+3cd

Version
3.1

Year Assessed
2008

Assessor/s
Urbani, B., Morales, A. L., Link, A. & Stevenson, P.

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

Contributor/s

Justification
Listed as Critically Endangered as there is reason to believe the species has declined by at least 80% over the past 45 years (three generations) due primarily to hunting and habitat loss. Over the coming 45 years, this decline is likely to reach similar proportions due to continuing habitat loss.

History
  • 2003
    Critically Endangered (CR)
  • 2000
    Endangered (EN)
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Both of the subspecies of Ateles hybridus are listed as Critically Endangered on IUCN Red List and are listed in IUCN's “world’s 25 most endangered primates." The biggest threats to their populations are forest fragmentation and degradation, as well as the pet trade and illegal hunting. Large proportions of A. hybridus habitats have been converted to lands for agriculture and a lot of the remaining habitats are surrounded by human populations and roads. Only 0.67% of their distribution is protected, so there is a urgent need for protected areas and national parks, which also could include two other threatened endemic primates, white footed tamarins (Saguinus leucopus) and woolly monkeys (Lagothrix lugens). As mentioned in the habitat section, A. hybridus prefers continuous, secondary forests, but only 9% of Ateles h. brunneus potential range remains in that condition. The large body size of A. hybridus and their slow reproductive rate, with late maturation and long interbirth intervals, constrain them from recovering from population declines and make them more vulnerable to extinction.

A combination of ex-situ, in-situ, and education projects is necessary to protect this endangered species. To estimate the density and distribution for this species is also a priority research topic for conservation purposes. Protected areas are necessary for their survival as well as breeding programs for captive animals. Also surveys are much needed to establish population densities of some of the subspecies and to determine local threats.

Brown spider monkeys possess all of the natural history characteristics that accompany higher risk of extinction: large body size, slow reproductive rate, being a food specialist, having a large home range, long life span, late maturation, and long interbirth intervals. All this constrains the species from recovering from population declines, and make them more vulnerable to extinction. The large-scale fragmentation and deforestation of rainforest is a direct threat to A.hybridus as secondary forest is unsuitable as habitat for them. A. hybridus inhabit fragmented habitats and we know suprisingly little about the processes that underpin survival in fragmented habitats. Small- population effects might be too serious to be reversed. It would be unfortunate to lose a species that we still know so little about. We have just begun to understand aspects of their behavior and ecology. Further studies would increase our understanding of, for example, their complex social structure and hierarchies.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: critically endangered

  • Mittermeier, R., J. Ratsimbazafy, A. Rylands, L. Williamson, J. Oates. 2008. Primates in Peril: The World’s 25 Most Endangered Primates 2006–2008. Primate Conservation, 22: 1-40.
  • Palacios, E., A. Morales-Jiménez. 2007. "Variegated or Brown Spider Monkey, Ateles hybridus I. Geoffroy, 1829." (On-line). Accessed January 13, 2009 at http://www.primate-sg.org/hybridus07.htm.
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Status

Classified as Critically Endangered (CR) on IUCN Red List (1). Two subspecies are recognised: the brown spider monkey (A. h. brunneus) and the hybrid spider monkey (A. h. hybridus) are both classified as Critically Endangered (CR) on the IUCN Red List (1).
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Population

Population
In Colombia, Bernstein et al. (1976a) calculated a density of 9-14 individuals/km for Ateles hybridus hybridus in the San Lucas mountains. Green (1978) calculated densities of 8.2-9.6 groups/km at his study site, which if multiplied by his average group size (3.3 individuals) seems to suggest higher densities at his Cerro Bran site when compared with the other study site.

There is no reliable population information available for Venezuela (B. Urbani pers. comm.).

Population Trend
Decreasing
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Threats

Major Threats
In Colombia, both Ateles hybridus hybridus and Ateles hybridus brunneus are subject to habitat loss and to hunting. The habitat of A. h. hybridus is extremely fragmented, and there may be few populations of an adequate size to be viable in the mid- to long-term (Defler et al. 2003).

Habitat alteration appears to be the most important threat to the Venezuelan population of A. h. hybridus. The lowland forest of the state of Zulia and the piedmond of the Perij Mountains are heavily destroyed from expanding cattle-ranching activities (B. Urbani, unpubl.). Portillo and Velsquez (2006) undertook a gap analysis for this primate species within the Perij Mountains and found that, while the total forest extent is still very large (813,257 ha), only 30% is relatively well preserved and protected. The rest remains affected by rapid human expansion and land clearance. Also in the Perij Mountains, these monkeys seem to be favourite game animals (Lizarralde 2002). In central Venezuela, some areas that were reported with these monkeys (Cordero-Rodrguez and Biord 2001) were resurveyed by Duque (2007) without reports of any sightings; most of the area is already converted to secondary vegetation. Also in this region, B. Urbani (unpubl.) found that buffer areas around the protected areaswith confirmed populations of Ateles hybridus hybridus (P. N. Guatopo) and unconfirmed populations (M. N. Cueva Alfredo Jahn, P. N. Henry Pittier, P. N. San Esteban and P. N. El vila)are transformed into cleared areas for slash-and-burn agriculture and human settlements as well as secondary forests. The lowland forest from the eastern part of the Andean Mountains, which are San Camilo and Ticoporo, are under severe pressure from logging.
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Both subspecies of variegated spider monkey are considered to be at enormous risk in Colombia (1), having suffered widely from hunting for food (2), and habitat destruction due to human encroachment and conversion to agricultural land (4). Sadly, the species' large size deems it an easy target for hunters, while its slow reproductive rate and generally low population densities makes it especially vulnerable to population collapses as a result of over-hunting (4). The habitat of the hybrid spider monkey (A. h. hybridus) is patchily distributed and there is a concern that few populations remain that are of an adequate size to be viable in the mid to long term. Populations are failing to be actively managed, even within protected areas. However, the brown spider monkey (A. h. brunneus) does not occur in any protected area, and its population size is thought to be much smaller than that of the nominate subspecies (1). The brown spider monkey (A. h. brunneus) has a small geographic range where forest loss, degradation and fragmentation are unfortunately widespread. Thus, this subspecies has been officially recognised in 2004 and 2006 as one of the world's 25 most endangered primates (4).
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Management

Conservation Actions

Conservation Actions
Ateles hybridus hybridus is found in several protected areas in Colombia, including: Catatumbo-Bari National Natural Reserve (158,125 ha); Tam National Natural Park (48,000 ha); El Cocoy National Natural Park (306,000 ha); and
Parque Nacional Sierra Nevada de Santa Marta (383,000 ha) (Defler 2004). They may also occur in Chingaza Natural National Park (50,374 ha).

In Venezuela, the species occurs in the Guatopo National Park (92,640 ha), which is of particular importance because it is one the major water reservoirs for the capital city, Caracas. The Sierra de Perij National Park (295,288 ha) is the other major protected area with brown spider monkeys. In these national parks, enforcement against hunting and wood extraction is needed. There are no NGOs working actively with Ateles hybridus hybridus as target species, and governmental agencies should improve their conservation efforts. However, there is interest for continuing with surveys on these primates especially in central Venezuela as well as an awareness programme particularly at a local level. It is also fundamental to increase the number of park rangers and improving their economical condition. They also occur in Caparo Forest Reserve (Venezuela) (B. Urbani pers. comm.).

Bernstein et al. (1976a) showed the effect of forest disturbance, especially on A. h. brunneus (and Lagothrix lugens), and (1976b) made a plea for the establishment of reserves for this and other threatened primate taxa. Fortunately, the Serrana de San Lucas in southern Bolvar still contains extensive forest which has been identified as a possible national park site. The establishment of a San Lucas National Park ought to have high priority in Colombia, since it would preserve many elements of the Nech refugium, including Saguinus leucopus and Lagothrix lugens. However, the presence of political insurgents, the military and some mine fields make the region very difficult for work and for the presence of the government. The Cienaga de Barbacoas represents another priority area for consideration for the creation of a protected area.

Censuses are required for a better understanding of the status of Ateles hybridus, and local populations need to be clearly identified and actively managed, something that is not taking place even in the protected areas where A. h. hybridus is known to occur.

This species is listed on Appendix II of CITES.
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Conservation

The hybrid spider monkey (A. h. hybridus) is known to occur in 4 protected areas: Catatumbo-Barí, El Cocuy National Park and Tamá National Park in Colombia, and Guatopo National Park in Venezuela (2). Although not in any protected areas, a refuge remains for the brown spider monkey (A. h. brunneus) in the Serranía de San Lucas in southern Bolívar, which has been identified as an important site for the potential establishment of a national park. A park in the Serranía San Lucas would protect a number of species endemic to the region, including two other threatened primate species, the white-footed tamarin (Saguinus leucopus) and woolly monkey (Lagothrix lagothricha lugens). However, the region has been a centre of civil unrest for years, and census work there would be hazardous, since guerilla groups have placed anti-personnel mines in some parts of the mountain range. Although limiting opportunities for surveys and conservation work, this civil unrest has proved to be a double-edged sword, since it is also probably the reason why forest is still remaining, considering the insatiable destruction of the forests elsewhere across the country (4).
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Relevance to Humans and Ecosystems

Benefits

There are no known adverse effects of Ateles hybridus on humans.

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Brown spider monkeys are critical members of the rainforest ecosystems they live in, they are important for forest regeneration through seed dispersal.

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Wikipedia

Brown spider monkey

Physical Description

Brown spider monkeys have long and thin limbs with their forelimbs being longer than their hind limbs. They also have a distinctive 75 cm long flexible, thin and prehensile tail which at times acts like a fifth limb. Tip is hairless with ridged skin for better grip. All these features of their body makes it possible for them to climb trees at high elevations, hang and swing from one tree to another without having to lower themselves to the ground often. Their hands are slightly curvy looking with smaller thumbs. Adult males weigh between 7.9 and 9.1 kg and adult females weigh between 7.5 and 9 kg. Their average adult body length is about 50 cm. Their coloration ranges from light brown to dark on upper parts including the head. Their most distinctive characteristic is their white triangular forehead patch alhough not all spider monkeys have this. Some, even though very unusual, possess pale blue eyes.[3]

Lifespan/Longevity

Average lifespan of a spider monkey is 27 years, however, in captivity that can be increased by 10 or more years.[4]

Near extinct

The Brown spider monkey is among "The World's 25 Most Endangered Primates", and is one of only two Neotropical primates (the other being the yellow-tailed woolly monkey) to have been included in this list in both 2006-2008 and 2008-2010.[5] They were recognized as species only a decade ago. Habitat loss, forest fragmentation and Hunting are the major threats for the remaining monkeys.

Range

Brown Spider monkeys in Colombia are found from the right bank of the Rio Magdalena in the Departments of Magdalena, Cesar. The south western portions of Guajira in the northernmost parts of the Serrania de Perija, and in the middle Rio Magdalena valley at least to the Departments of Caldas and Cundinamarca.[6]

Habitat and Ecology

Brown spider monkeys are normally found in elevations between 20–700 m. Even though they spend most of their time in high elevations to move about, they occasionally descend to eat soil and drink water. Since they like trees and foraging in high canopies, they prefer forests that have not been disturbed, also known as primary forests. This is because primary forests offer lifestyle they are comfortable in, for example endless canopies, tall trees, and many fruiting trees that disturbed forests do not offer.[7] Brown spider monkey's always travel in small groups, and instead of walking or running on all fours, they travel mostly by swinging and climbing between trees.[2]

Diet

Ateles hybridus mainly forage in the canopies of forests and rely mostly on their senses of sight, smell, taste, and touch to find food. Brown spider monkeys are mainly herbivores and frugivores. A main component of the brown spider monkey’s diet is ripe fruit. 83% of their diet is lipid rich fruits. However in dryer seasons where fruit is less abundant, brown spider monkeys feed on leaves, seeds, flowers, bark, honey, decaying wood, and occasionally insects such as termites and caterpillars.[2] Ateles hybridus feed on different species of figs year around. Scientists have observed spider monkeys eating soil and clay, and hypothesized that the reasons for this behavior could be to obtain minerals from the soil, for phosphorus, or in order to maintain a pH- balance in their digestive system. Brown spider monkeys find water to drink on the forest floor at “salado sites.” Competition for food occurs between spider monkeys and other frugivorous primates.[8]

Goldstirn-Klammeraffe (Ateles belzebuth hybridus).JPG

Population

The population is estimated to have decreased by at least 80% and some populations have already been extirpated.[5] Few remaining populations are of adequate size to be viable long-term.[2] The exact number of Brown spider monkeys present today is unknown, but breeding success has been limited and no births were reported between May 2009 and May 2010.[9] Habitat loss is ongoing within its range, and an estimated 98% of its habitat already is gone.[10] It is also threatened by hunting (in some regions it is the favorite game) and the wild animals trade.[5] Although habitat destruction is one of the utmost threats the brown spider monkey faces, one study in particular shown no significant difference between population densities inside versus outside forest areas disturbed by loggers. It has been hypothesized that this anomaly is due to the sample being taken from El Paujil reserve, which is a protected area and may serve as refuge from other human activities, namely poaching.[11] A small population of fewer than 30 individuals of the subspecies A. h. brunneus has been discovered in a protected area of Colombia, the Selva de Florencia National Park. This is the southernmost population of the brown spider monkey and the only population found in a protected area.[12]

Natural Threats

Ateles hybridus have a relatively large body size, and their largest threats are jaguars (Panthera onca), mountain lions (Felis concolor), harpy eagles (Harpia harpyja), and crested eagles (Morphnus guianensis) <ref(Chapman and Onderdonk, 1998; Cowlishaw and Dunbar, 2000; Link and Morales Jimenez, 2008; Takahashi, 2008; Urbani, et al., 2008/>. Brown spider monkeys are known to shake branches in order to ward off potential predators. Brown spider monkeys are also targeted by humans as a favorite game species, especially in Colombia,[13] to be sold as pets in which case the mother is killed and her baby is sold into the pet trade <ref(Chapman and Onderdonk, 1998; Cowlishaw and Dunbar, 2000; Link and Morales Jimenez, 2008; Takahashi, 2008; Urbani, et al., 2008/>. The species suffers from habitat destruction due to conversion to agricultural land, clear-cutting,[13] logging especially in the lowland forest in the Andean mountains,[2] conversion to secondary forest, and disturbance to potential corridors by humans. Brown spider monkeys are most threatened by habitat loss and hunting.[13] Habitat disturbance is a major risk for the Venezuelan population of brown spider monkeys. Humans have destroyed massive spans of forest to raise cattle on.[2]>


References[edit]

  1. ^ Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. p. 151. OCLC 62265494. ISBN 0-801-88221-4. 
  2. ^ a b c d e f Urbani, B., Morales, A. L., Link, A. & Stevenson, P. (2008). "Ateles hybridus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 31 March 2014. 
  3. ^ (Ankel-Simons, 1999; Fleagle, 1999; Morales Jiménez, 2007; Takahashi, 2008)
  4. ^ (Takahashi, 2008)
  5. ^ a b c Mittermeier, R.A.; Wallis, J.; Rylands, A.B.; Ganzhorn, J.U.; Oates, J.F.; Williamson, E.A.; Palacios, E.; Heymann, E.W.; Kierulff, M.C.M.; Long Yongcheng; Supriatna, J.; Roos, C.; Walker, S.; Cortés-Ortiz, L.; Schwitzer, C., eds. (2009). "Primates in Peril: The World's 25 Most Endangered Primates 2008–2010" (PDF). Illustrated by S.D. Nash. Arlington, VA.: IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI). pp. 1–92. ISBN 978-1-934151-34-1. 
  6. ^ Arauca (Hernández-Camacho and Cooper 1976; Defler 2003, 2004).
  7. ^ (Chapman and Onderdonk, 1998; Morales Jiménez, 2007; Takahashi, 2008; Urbani, et al., 2008)
  8. ^ (Chapman and Onderdonk, 1998; Cowlishaw and Dunbar, 2000; Link and Morales Jimenez, 2008; Takahashi, 2008; Urbani, et al., 2008)
  9. ^ International Species Information System (2010). Ateles hybridus. Retrieved 21 May 2010.
  10. ^ Fundación ProAves (2010). Tragic demise of the Magdalena Spider Monkey. Retrieved 21 May 2010.
  11. ^ BioOne Online Journal (2008). [1] Retrieved 22 October 2013.
  12. ^ Dell'Amore, Christine (27 January 2012). "Near-Extinct Monkeys Found in Colombian Park". Daily News. National Geographic. Retrieved 9 January 2012. 
  13. ^ a b c Russell A. Mittermeier, Christoph Schwitzer, Anthony B. Rylands, Lucy A. Taylor, Federica Chiozza, Elizabeth A. Williamson and Janette Wallis (eds.). 2012. Primates in Peril: The World’s 25 Most Endangered Primates 2012–2014. IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), Conservation International (CI), and Bristol Conservation and Science Foundation, Bristol, UK. 40pp.


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