- Common Name:
- Woolly monkeys
- Scientific Name:
- Average Life Span In Captivity:
- 30 years
- Up to 1.6 feet tall
- 15 to 21 pounds
What is a woolly monkey?
An animal called a woolly monkey seems like it should live in the frozen north, not the sweltering Amazon Basin. But the thick coat of fur covering these large primates protects them from the sun, rain, and insect bites of their native habitats in the forests and cloud forests of Peru, Columbia, Ecuador, Bolivia, and Brazil.
Woolly monkeys were once considered four species: the gray, Columbian, silvery, and Peruvian yellow-tailed woolly monkeys. More recent genetic studies suggest there are only two species—the Peruvian yellow-tailed and the common (or brown) woolly monkey. The gray, Columbian, and silvery woolly monkeys were reclassified as subspecies of the brown woolly monkey.
The coloring of their coats is the main difference between woolly monkey species and subspecies. The gray woolly monkey has a coarse, short, gray coat, for example, while the Peruvian yellow-tailed woolly monkey has longer, softer fur the color of dark chocolate with a distinctive yellow stripe on the underside of its tail and white hairs around the mouth. They all have round heads that are darker than their bodies—and, in the case of the gray and yellow-tailed monkeys, they also have large, dark eyes and expressive faces.
Woolly monkeys have long, strong prehensile tails with a thick pad on the end that helps these arboreal animals grip branches. It also helps them be balanced, stable climbers. Woolly monkeys spend most of their time high in the tree canopy. On the rare occasions when they descend to the ground, they usually walk on all fours, but occasionally they’ll also walk upright, balancing with their arms.
Diet and behavior
Woolly monkeys live in social groups averaging about 50 individuals and led by an alpha male. These groups can spread out over several acres, and members keep in contact with each other through vocalizations. Sometimes group territories overlap, though the monkeys won’t fight over it. Some individuals may split off to join other groups, while outsiders may join a home range group, a practice known as fission-fusion dynamics.
Wooly monkeys primarily are fruit eaters, but they’ll also eat leaves, nectar, and flowers, helping spread seeds through the environment. Fruit-eaters as large as woolly monkeys are rare in this environment, and they’re able to drop seeds far from the parent trees—meaning the plants won’t have to compete for resources. These monkeys will also occasionally eat insects like beetles, ants, and mantids.
As with other primate species, grooming is an important form of socializing for woolly monkeys, strengthening social bonds as they keep each other healthy. High-ranking males and females are groomed by those wishing to curry favor; young females groom their mothers; and juveniles both groom and play with each other.
Woolly monkeys are polygamous. Females usually solicit males, often by shaking their heads with open-mouthed grins or by retracting their lips and opening and closing their mouths, a gesture called “tooth chatter” or “click.” Males reach maturity at age five and females between six and eight years old. There’s no external sign of when these animals are in heat, and mating occurs year-round.
Gestation lasts about seven-and-a-half months, after which the female will give birth to a single offspring. Infants weigh about a pound at birth and are born with their eyes open. Males provide care for both the female and offspring for a few weeks and then gradually stop.
Infants attach to their mother’s belly for the first few weeks after birth, then relocate to her back. They begin to become more independent at about five months but still nurse for about a year.
Threats and conservation
Woolly monkeys face many threats, although some species are faring worse than others. The International Union for Conservation of Nature lists the common woolly monkey as vulnerable to extinction, while its gray subspecies is considered endangered. The Peruvian yellow-tailed woolly monkey is critically endangered. Woolly monks reproduce slowly, with a three-year interval between births, making their declining numbers particularly concerning.
Housing and commercial development bite into woolly monkey habitat, as do farming, ranching, logging, mining, roads, and railroads. Woolly monkeys are also hunted by jaguars, birds of prey, and humans, though hunting is illegal in some places or under some circumstances. People hunt them for their fur, meat, and fat, which is used to make cooking oil and medicines.
Infants are prized in the exotic pet trade. Sometimes poachers shoot the mother to take an infant, who may not survive in captivity.
In 2021, the woolly monkey pet trade became the basis of a high-profile legal battle in Ecuador. The case centered on a gray woolly monkey named Estrellita, who lived as a pet for 18 years before she was put in a zoo and died. Ecuador’s high court ultimately ruled that wild animals have rights that are protected under the country’s constitution.
The monkeys, which inhabit numerous protected park and forest areas, are subject to international protections under CITES, the treaty that governs the international wildlife trade. The Peruvian yellow-tailed woolly monkey cannot be commercially traded across borders, and the common woolly monkey is subject to some trade restrictions.
Did you know?
— Banco Central de Reserva del Perú
A 2015 study found that some female gray woolly monkeys breastfeed adult males, likely to make alliances with high-ranking individuals.
— Mammalian Biology
Like other primates with prehensile tails, woolly monkeys can support all their considerable body weight with their tail alone.
— Western Undergraduate Research Journal: Health and Natural Sciences
The woolly monkey’s genus, Lagothrix, comes from the Greek lagos, hare, and thrix, hair—making the animal's name “hare hair” for their thick, rabbit-like coats.
— University of California San Diego