The endangered Central American Squirrel Monkey (Saimiri oerstedii) is the smallest and rarest monkey found in Costa Rica. There are only a few thousand of these monkeys remaining in a relatively small geographic area along the southern Pacific coast of Costa Rica and the adjacent northern Pacific coast of Panama, and their numbers will continue to decline if the destruction and fragmentation of their forest habitat continues.

Central American Squirrel Monkeys are highly arboreal and rarely descend to the ground or venture into open areas where they would be quite vulnerable to their many predators (jungle cats, large raptors, etc.), so the clear-cutting of forests can leave bands of these monkeys essentially trapped in isolated pockets of forest that are too small to adequately sustain them. Central American Squirrel Monkeys can also be harmed by power lines, pesticides, and other things related to agriculture and land development.

The best places to still see Central American Squirrel Monkeys are in Costa Rica's Corcovado National Park and Manuel Antonio National Park. We didn't see any in the nearby national park, but we did see a small band of Central American Squirrel Monkeys not too long after sundown one evening in the town of Manuel Antonio, Costa Rica.

These Central American Squirrel Monkeys were foraging in some trees alongside a very busy road and surprisingly didn't seem to be disturbed by all of the noise and activity. These monkeys are omnivores, but they mainly feed on fruit and large insects. They will also capture and eat roosting bats. Central American Squirrel Monkeys mainly forage during the daytime, but like these ones, they will also remain active for an hour or so after sundown as well.

Central American Squirrel Monkeys are small, only about 1 foot (30 cm) long, not including their long, non-prehensile, black-tipped tails, and they can be recognized by their white face, chest, and ears, dark gray muzzle, blackish to dark gray crown, and by their distinctive reddish brown back, feet, and forearms. Squirrel Monkeys have fingernails instead of claws, as can be seen on the shy-looking Central American Squirrel Monkey above.