Geoffroy’s Spider Monkey: A Threatened Primate of Central America
Geoffroy’s spider monkey (Ateles geoffroyi), also known as the black-handed spider monkey or the Central American spider monkey, is a species of spider monkey, a type of New World monkey, from Central America, parts of Mexico and possibly a small portion of Colombia. There are at least five subspecies.
It is one of the largest New World monkeys, often weighing as much as 9 kg (20 lb). Its arms are significantly longer than its legs, and its prehensile tail can support the entire weight of the monkey and is used as an extra limb. Its hands have only a vestigial thumb, but long, strong, hook-like fingers. These adaptations allow the monkey to move by swinging by its arms beneath the tree branches.
Geoffroy’s spider monkey lives in fissionâfusion societies that contain between 20 and 42 members. Its diet consists primarily of ripe fruit and it requires large tracts of forest to survive. As a result of habitat loss, hunting and capture for the pet trade, it is considered to be endangered by the IUCN .
The genus name Ateles means “imperfect”, a reference to the vestigial thumb. The species name geoffroyi is in honor of French naturalist Ãtienne Geoffroy Saint-Hilaire . Agreement over the number of spider monkey species is not universal. Kellogg and Goldman (1944) based their classification on fur color, and Groves (1989) based his on fur color and geographic distribution. Kellogg and Goldman differentiated Geoffroy’s spider monkey from other species by its dark black head, hands and wrists. Recent studies use mitochondrial DNA to help differentiate species. Such studies by Collins and Daubach (2000, 2001, 2006) indicate the Geoffroy’s spider monkey is more closely related to the white-fronted spider monkey, A. belzebuth, and the brown spider monkey, A. hybridus, than it is to the red-faced spider monkey, A. paniscus.
Distribution and Habitat
The black-handed spider monkey is found along both coasts of Mexico from Tamaulipas in the northeast and Jalisco in the west south to northwestern Colombia. It inhabits mature rainforest and montane forest.
Head and body length ranges from 305 to 630mm, and tail length from 635 to 840mm. With respect to body length, Ateles geoffroyi has extremely long limbs and tail. The head is small and the muzzle substantial. The upper fur is black, brown, or reddish and the face is often marked with a pale mask of unpigmented skin around the eyes and muzzle. The arms and feet are dark and the underparts paler (white, pale brown, reddish, or buff). Female spider monkeys have an enlarged clitoris that resembles the penis of males.
Reproduction and Lifespan
Ateles geoffroyi does not appear to have a regular breeding season. Female black-handed spider monkeys have an estrous cycle of 24 to 27 days; mating is restricted to a period of two to three days. Gestation lasts 226 to 232 days and one young is born. Ovulation is suppressed by lactation and births occur at two to four year intervals. Males are sexually mature in five years and females in four. The longest recorded captive lifespan is 33 years.
Behavior and Ecology
These animals are social and tend to form groups of approximately thirty individuals. Groups of up to 100 have been reported. For the most part, these large groups split into smaller subgroups to forage and only for a few weeks out of the year is the whole group together