Brown-headed spider monkey  (Ateles fusciceps)

Classified as Vulnerable (VU) on the IUCN Red List. Subspecies: The Colombian black spider monkey, Ateles fusciceps rufiventris, and the brown-headed spider monkey A. f. fuscicpes, are listed as Critically Endangaered (CR) on the IUCN Red List (1).

The large and graceful brown-headed spider monkey is one of the most threatened animals in Ecuador (5). Like all spider monkeys, the brown-headed spider monkey has long, thin arms; hook-like hands with no thumbs; a pot belly; and a prehensile tail which is used like a fifth limb (2) (7) (8). As an infant, the brown-headed spider monkey has a pink face and pink ears, but as it grows older the hair on its head turns brown (2). Adult females and males are practically indistinguishable; both have bodies of very dark brown or black, depending on the subspecies (2). The calls of the brown-headed spider monkey include a high-frequency whinny (9).

Two subspecies of the brown-headed spider monkey are recognised, with each living in a different area. The subspecies Ateles fusciceps fusciceps occurs in Ecuador (1), and may also occur in Colombia, although this has yet to be confirmed (10), while the range of Ateles fusciceps rufiventris (Colombian black spider monkey) extends from south-western Colombia to eastern Panama (1). 

The brown-headed spider monkey occupies the greatest range of forest habitats of any of the Colombian spider monkeys; it has been recorded in dry forest, humid forest and cloud forest, as high as 2,500 metres above sea level (1). In Ecuador, the brown-headed spider monkey prefers wetter forest and lives in tropical and subtropical humid forests from 100 to 1,700 metres above sea level (6). 

The brown-headed spider monkey moves around in the daytime foraging for ripe fruit, which comprises 83 percent of its diet (9). Through this diet, this species playsan important ecological role within the forest as a seed-disperser (1). At the beginning of the dry season, when fruit is scarce, it consumes a greater amount of leaves, flowers, seeds, bark and honey, and will also occasionally eat small insects (2). The brown-headed spider monkey almost never comes down from the trees but spends its days climbing and swinging through the upper levels of the canopy (7). 

Like all spider monkeys, the brown-headed spider monkey lives in a fission-fusion community consisting of many males and many females (8), in which large groups (of 20 to 100 individuals) divide into smaller, temporary subgroups for feeding (1). After a gestation period of seven to eight months a single offspring is born. The young first leaves its mother to play at ten weeks, but will continue to ride on its mother’s back when moving through the forest until 16 weeks of age (9). The brown-headed spider monkey becomes sexually mature at about four years and has a life span of around 24 years (11).

Due to its large size and the desirability of its meat, the brown-headed spider monkey has been hunted by humans for centuries (6). Compounding the threat of hunting is the impact of habitat loss; in Colombia it has been estimated that 30 percent of Ateles fusciceps rufiventris’ habitat has been lost in the last ten years (1), and the population size of Ateles fusciceps fusciceps has decreased by 80 percent as a result of habitat loss (6). 

Hunting of the brown-headed spider monkey is prohibited in Ecuador (5), and it also receives some protection from international trade under its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that any international trade in this species should be carefully regulated (4).  This species also occurs in several protected areas, including Los Cedros Protected Forest in Ecuador and Los Katios Natural National Park in Colombia (1), which should hopefully protect some populations from the threat of habitat loss.

For effective conservation measures for the brown-headed spider monkey to be implemented, further research is required on the range, size and habitat of the remaining populations, the extent to which it is trafficked in the pet- and meat-trades, and its ability to cope with deforestation, forest fragmentation and proximity to humans. Captive breeding programmes have also been recommended to increase the population sizes of the groups which persist (1).

To learn more about primate conservation see:

• IUCN/SSC Primate Specialist Group:
  http://www.primate-sg.org/
• Neotropical Primate Conservation:
  http://www.neoprimate.org

To find out more about the brown-headed spider monkey and conservation projects, see:

•  Mohamed bin Zayed Species Conservation Fund
  http://www.speciesconservation.org/projects/Brown-headed-Spider-Monkey/336
• EDGE of Existence:
  http://www.edgeofexistence.org/mammals/species_info.php?id=106