Spider Monkey
Spider monkeys are large primates of the New World, with seven species that range from southern Mexico through Central America to the Amazon, the Guianas and Bolivia. They live in tall tropical forests, from lowland rainforest to dry forest and cloud forest, moving through the canopy with very long arms, hook shaped hands that have almost no thumb, and a prehensile tail with a bare, ridged pad at the tip that grips branches like a fifth hand. The tail is longer than the body. Ripe fruit makes up most of their diet, along with young leaves, flowers and seeds. Because they swallow seeds whole and travel far each day, they are among the most important seed dispersers in the Americas. They live in communities that split into small foraging parties and come back together, a system known as fission fusion, and it is the females, not the males, that leave home to join a new community. Females give birth to a single baby only about once every three years, so populations recover very slowly. Of the seven species, the IUCN lists one as Vulnerable, five as Endangered and one, the brown spider monkey of Colombia and Venezuela, as Critically Endangered.
What is a spider monkey?
Spider monkeys are the monkeys of the genus Ateles, a group of seven species that live in the tropical forests of Mexico, Central America and South America. Their name comes from the way they look when they hang from a branch: with their long, thin arms and legs and their long tail stretched out in every direction, they really do resemble a giant spider. They are among the largest monkeys in the Americas and belong to the family Atelidae, together with the howler monkeys, the woolly monkeys and the muriquis. The muriqui of the Atlantic Forest of Brazil is often called the woolly spider monkey, but it belongs to a different genus, Brachyteles, and is not a true spider monkey. Like other New World monkeys, spider monkeys have wide noses with nostrils that open to the sides. Their most unusual features are a prehensile tail strong enough to hold their whole weight and hands with only a tiny stub of a thumb, or none at all, which turns the fingers into a hook for swinging. Local names change from country to country: they are called maquisapa in Peru, marimonda in Colombia, coatá in Brazil and kwata in Suriname and French Guiana.
How many types of spider monkeys are there?
The IUCN recognizes seven species of spider monkey. Geoffroy's spider monkey, Ateles geoffroyi, also called the Central American or black handed spider monkey, is the only one north of Panama and lives from southern Mexico to Panama; it is Endangered, and several subspecies, such as the Mexican, Yucatán and Azuero spider monkeys, are named for where they live. The brown headed spider monkey, A. fusciceps, lives in the Pacific forests of Panama, Colombia and Ecuador and is Endangered; its Colombian form, almost entirely black, is often called the Colombian black spider monkey. The brown or variegated spider monkey, A. hybridus, of northern Colombia and western Venezuela, is Critically Endangered and one of the most threatened primates in the world. The white bellied spider monkey, A. belzebuth, lives in the western Amazon of Colombia, Venezuela, Ecuador, Peru and Brazil and is Endangered. The Peruvian or black spider monkey, A. chamek, of Peru, Bolivia and western Brazil, is Endangered. The red faced spider monkey, A. paniscus, an all black monkey with a bare reddish face, lives in the Guianas and northeastern Brazil and is the only Vulnerable species. The white whiskered spider monkey, A. marginatus, lives only in Brazil, between the Tapajós and Xingu rivers, and is Endangered.
How big is a spider monkey?
Spider monkeys measure about 30 to 63 cm from head to rump, but their tail adds another 63 to 92 cm, so the tail is clearly longer than the body. Most adults weigh between 6 and 10 kg, and males and females are about the same size. Their build is unusual for a monkey: a small, round head, a slim body and arms that are longer than their legs, which gives them their spidery look. The hands are long and narrow, and the thumb is either missing or reduced to a tiny stub, so the four fingers work as a hook that can catch a branch in mid swing without having to wrap around it. The feet keep a normal big toe and grip well. The tail is the real tool. Its last third is bare on the underside and covered in ridges, like a fingerprint, which gives it a firm grip and a fine sense of touch. It can hold the full weight of the monkey, so a spider monkey can hang only from its tail while it uses both hands to pick fruit. Coat colors depend on the species, from all black to brown, reddish or golden, often with a pale belly or white whiskers.
Where do spider monkeys live?
Spider monkeys live from southern Mexico to Bolivia and central Brazil. In Mexico and Central America there is only one species, Geoffroy's spider monkey, which the IUCN lists in Mexico, Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. In Mexico it lives in the states of Chiapas, Oaxaca, Campeche and Quintana Roo, in forests such as the Lacandon Jungle and Calakmul. In El Salvador only a few small groups remain, in the forests of Usulután. South America has the other six species, spread over Colombia, Venezuela, Ecuador, Peru, Bolivia, Brazil and the three Guianas, with the largest areas in the Amazon rainforest. They are not found in the Atlantic Forest of Brazil, where the muriqui lives instead. Spider monkeys need tall, mature forest with a continuous canopy, and they spend almost all their time in the upper levels of the trees, rarely coming down to the ground except to drink or to eat mineral rich soil. Most live in lowland rainforest, but Geoffroy's and the brown headed spider monkey also use dry forest and cloud forest up to about 2,500 meters. Because they need large areas of old forest to find enough fruit, they are usually among the first animals to disappear when a forest is cut or broken into pieces.
What do spider monkeys eat?
Ripe fruit is the center of the spider monkey diet. In most field studies it makes up around three quarters or more of what they eat through the year, with figs and the soft fruits of many canopy trees among their favorites. When fruit is scarce, they fill the gap with young leaves, flowers, seeds, aerial roots and sometimes bark, and they occasionally eat insects such as termites and caterpillars. Because they depend so much on ripe fruit, which is spread out and appears in different trees at different times, they travel long distances every day and seem to remember where and when each tree will be ready. Many seeds pass through their gut whole and come out far from the parent tree, sometimes more than a kilometer away, which makes spider monkeys some of the most effective seed dispersers in the forests of the Americas. Some large seeded trees depend heavily on them, and studies have found that forests where spider monkeys were hunted out regenerate those trees more poorly. Spider monkeys also visit natural salt licks, where they eat soil and drink mineral rich water, a habit that probably helps them get minerals that fruit lacks and may help neutralize plant toxins.
How do spider monkeys live in groups?
Spider monkeys live in communities that can number from about a dozen to several dozen animals, but they are rarely all together. Most of the day the community is split into small parties of two to eight monkeys that forage on their own and change members often, then join up again at a big fruiting tree or a sleeping site. Scientists call this a fission fusion society, the same system used by chimpanzees, and it lets the monkeys spread out when fruit is scarce and gather when it is plentiful. Another surprise is who leaves home. In most monkeys the young males move away, but in spider monkeys it is the young females that leave to join a new community, while the males stay for life with their brothers and male relatives and defend the community territory together. Females give birth to a single baby after a pregnancy of about seven and a half months. The baby clings to its mother for months, nurses for a long time, and a mother only has another baby after roughly three years; a long study in Santa Rosa, Costa Rica, measured an average gap of almost 35 months. Spider monkeys keep in touch with a rich set of calls, including a horse like whinny that helps scattered parties locate each other, as well as barks, screams and chatters.
Can a spider monkey be kept as a pet?
Spider monkeys are wild animals, and keeping them as pets causes serious harm to the monkeys and to wild populations. Baby spider monkeys sold in markets are usually taken from the wild, and the most common way to get one is to shoot the mother, so each baby in the pet trade often means at least one adult female lost from a population that already breeds very slowly. Many babies die from stress, poor food or disease before they are ever sold. The ones that survive grow into strong adults that need to climb and swing over large areas, eat a varied diet of fresh fruit and leaves, and live with other spider monkeys. In a house they often become frustrated and can bite hard, and many end up locked in small cages or abandoned. They can also pass diseases to people and catch human ones. For these reasons, keeping or selling wild spider monkeys is illegal in most of the countries where they live, and all species are listed by CITES, which controls or bans their international trade; two Central American subspecies are in Appendix I, the strictest level. Rescue centers in Mexico, Central America and the Amazon care for hundreds of confiscated spider monkeys, and returning them to the wild is difficult and slow.
Are spider monkeys endangered?
Yes. All seven species are threatened and all are declining. In its most recent assessments, made between 2015 and 2020, the IUCN lists the brown spider monkey of Colombia and Venezuela as Critically Endangered; Geoffroy's, the brown headed, the white bellied, the Peruvian and the white whiskered spider monkeys as Endangered; and the red faced spider monkey of the Guianas as Vulnerable. For most of them the IUCN expects a decline of at least half over three generations, which for these slow breeding monkeys means about 45 years. The two big threats work together. The first is the loss of mature forest to cattle ranching, farms, logging, roads and, in some areas, mining and oil extraction. The second is hunting. Spider monkeys are large, move in the open canopy and call loudly, so they are easy targets, and with only one baby every three years or so, a population can collapse even under light hunting. In many forests that still look intact, spider monkeys have already vanished. The pet trade adds more pressure. On the positive side, large protected areas such as Calakmul, the Maya Biosphere Reserve, Manu and Yasuní still hold healthy populations, and community reserves like Punta Laguna in Yucatán show that local people can protect them.
