Howler Monkeys and Spider Monkeys: Atelidae

Physical characteristics: Geoffroy's spider monkeys have a coarse, shaggy coat that comes in yellow, red, or black, turning lighter on the undersides. The black hands and feet are very long and spidery, giving the monkeys their name. The hands have underdeveloped thumbs. White cheek hair is raised, and the eyes are surrounded by pale skin to form a mask. The prehensile tail, at 25 to 33 inches (63.5 to 84 centimeters), is longer than the head and body length of 12 to 24.8 inches (30.5 to 63 centimeters). The prehensile tail enables the large animal to hang from a sturdy branch to pick fruits at the end of thin branches. The monkey weighs 13 to 20 pounds (6 to 9 kilograms).

Geographic range: Geoffroy's spider monkeys are found in Mexico, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama.

While they usually travel on all fours, or use their arms to swing from branch to branch, Geoffroy's spider monkeys can also jump down through forest gaps of over 33 feet (10 meters). (Erwin and Peggy Bauer/Bruce Coleman Inc. Reproduced by permission.)

Habitat: Geoffroy's spider monkeys prefer the top level of the forest canopy, where ripe fruits and young leaves are abundant. They occasionally descend to the middle layers. They inhabit mountain forests and mangroves.

Diet: Spider monkeys eat mainly ripe fruits. They especially prefer those with big seeds. They also feed on young leaves, flowers, buds, insects, insect larvae, and bird eggs.

Behavior and reproduction: Geoffroy's spider monkeys form groups with over forty individuals. When food is scarce, smaller subgroups and lone monkeys split from the main group when feeding. They forage, search for food, mostly in the early morning, resting the remaining part of the day. Spider monkeys are agile climbers, using their tail as an extra limb to move through the trees. They also travel on all fours and brachiate. They can jump down through forest gaps of over 33 feet (10 meters). The monkeys tend to go back to the same sleeping areas at nightfall.

Adults have several partners. Some males and females are dominant over others, but males competing for the same females are seldom aggressive with one another. A female determines which partner she will take. On average, females give birth to a single infant every three years because infants take that long to be independent. This is the longest period of infant dependency known among monkeys. Young females leave home, while young males remain in their birthplace.

Geoffroy's spider monkeys and people: Humans hunt spider monkeys for food.

Conservation status: The IUCN does not list Geoffroy's spider monkey as a threatened species. ∎