Squirrel monkeys have a slender build with a short greyish dense coat. The ears, throat, head, back and legs are yellow to grey-green and the other parts are yellow to white. The face is white. The squirrel monkey has a tail that often curls over its shoulder when it is resting. Squirrel monkeys have thirty-six teeth; males have large upper canine teeth. Squirrel monkeys have nails instead of claws. They have been called 'small, nervous primates' as they are the smallest of the primate family Cebidae; they weigh about one to three pounds. The length of its body is nine to nineteen inches. Its tail is about fourteen to nineteen inches long.
The habitat of a squirrel monkey is in the northern part of South America to Peru, Bolivia, Paraguay, and Brazil. There are squirrel monkeys also in Costa Rica and Panama in Central America. The monkey lives in parts of virgin and secondary forests and in cultivated areas, usually along rivers and streams. Squirrel monkeys live in trees; they have great skill in moving through the trees.
A squirrel monkey is diurnal, feeding primarily in the early morning. The genus is second only to gibbons in being the most agile in trees, using their long tail as a fifth limb.
They form troops of from 2 to 30 monkeys that tend to frequently break up and rejoin. There are only a few males in a group.
Insects make up about 75% to 80% of a squirrel monkey's diet. They are not leaf eaters. One of the reasons that they are so "nervous" and in almost constant motion is that in the wild, they are always moving, flushing and foraging on insects.
Life Cycle and Young
Squirrel monkey females become sexually mature at approximately two and a half years old. Males become sexually mature at four years old. In the wild and in captivity, squirrel monkeys are seasonal breeders; birth usually occurs in the wet season, February to April. The gestation is about one hundred and forty-two days. Most of the births take place at night; labor takes about eighty to one hundred and sixty-five minutes. The baby clings to the back of the mother from birth. The father of the baby squirrel monkey doesn't help in raising the young, but other mothers with new young will. Squirrel monkeys give birth to only one monkey. The weight of the infant is about 112 grams for the males, and 106 grams for females. Very soon after the birth, the baby starts sucking. After twenty days, the baby starts to take some solid food. After a period of six months, the infant is completely weaned.
Enemies and Endangerment
Squirrel monkeys live in groups; this way, when a predator attacks, the pack of monkeys will kill the intruder. The squirrel monkeys' main enemy is the eagle, because eagles will soar down and pick the monkeys up. Porcupines and baboons also are enemies of monkeys.
One particular subspecies (Saimiri oerstedii oerstedii) on the Pacific coast of Costa Rica is very endangered, with probably less than 2000 animals in the wild. There is an effort underway by the Costa Rican Ministry for the Interior and the National Zoo to raise money to get an accurate census and for research on the natural biology of these animals