Saimiri oerstedii
Central American squirrel monkey

Saimiri oerstedii inhabits parts of the Pacific coast of Panama and Costa Rica (Nowak, 1999).

Little information is available about the habitat of S. oerstedii. In general, squirrel monkeys are arboreal and can be found in primary and secondary forests (Nowak, 1999), thickets, and mangrove swamps (Macdonald, 1984). They are also found in cultivated areas, usually around streams (Nowak, 1999). Saimiri oerstedii is known to inhabit humid Pacific slope forests (Reid, 1997).

Saimiri oerstedii is a small, slender monkey with a long tail (Reid, 1997). Much of their body fur is yellow brown in color with a pale yellow belly (Reid, 1997). Saimiri oerstedii can be distinguished from its sister species Saimiri sciureus because the crown of S. oerstedii is covered with black fur while that of S. sciureus is not (Chiarelli, 1972). Also, S. oerstedii has golden-red colored fur on its back (Rosenblum and Coe, 1985). Saimiri oerstedii weighs between 500 and 1100 g (Reid, 1997). Squirrel monkeys are typically 225 to 295 mm long with tails adding between 370 and 465 mm (Chiarelli, 1972).

Saimiri oerstedii is a social species. These monkeys travel in small troops (Baldwin and Baldwin, 1972). A troop of S. oerstedii has been observed to travel between 2.5 and 4.2 km a day with a home range around 0.175 square km (Baldwin and Baldwin, 1972). They begin foraging shortly before sunrise and continue until an hour or hour and a half after sunset, stopping only for brief rests or rainstorms (Baldwin and Baldwin, 1972). They huddle to minimize their exposure to the rain (Baldwin and Baldwin, 1972).

The diet of S. oerstedii consists mostly of invertebrates, small vertebrates, fruit, and flower nectar (Reid 1997). They also recognize the leaf-tents made by some fruit-eating bats and attack these tents to extract the bats (Reid 1997).

In general, members of the genus Saimiri feed primarily on fruit, berries, seeds, gums, leaves, buds, insects, arachnids and small vertebrates (Nowak, 1999). Nearly half of their diet is made up of fruit (Smuts et al., 1987). Most of their prey are immobile invertebrates (Smuts et al., 1987). When the animals find food in a tree, they often do not completely use up the resources available and may return to it in the future (Parker, 1990).

Squirrel monkeys in general (not specifically S. oerstedii) do benefit humans in that they are very widely used in biomedical research (Strier, 2000). Half of all squirrel monkeys imported to the United States in 1968 were used in labs while the other half were used in zoos and the pet trade (Nowak, 1999). They are often used for aerospace research as well (Rosenblum and Cooper, 1968). In the past, they have also been kept as pets for the European and American aristocracy (Hearn, 1983).

Although its sister species, S. sciureus, is quite abundant the IUCN places S. oerstedii on the endangered list (Nowak, 1999). The population has declined drastically with the destruction of forest habitats (Nowak, 1999). While abundant in the regions it inhabits, S. oerstedii is restricted to a very small area ( Smuts et al., 1987).

There have been some difficulties in finding information on S. oerstedii due to its rarity. In general, it is believed to be very similar to its sister species, S. sciureus (Moynihan, 1976). Also, the taxonomy of the genus is not completely resolved. Some authors divide Saimiri into two species, S. sciureus and S. oerstedii (Parker, 1990) while others see between five species (Nowak, 1999) and only one species which can be divided into two subspecies (Moynihan 1976).