Cyril Ruoso / Bare-eared Squirrel Monkey (Saimiri ustus) in tree, Peru

Cyril Ruoso / South American Squirrel Monkey (Saimiri sciureus) portrait, Peru

Mark Bowler / Common Squirrel Monkey (Saimiri sciureus ssp. macrodon) in tree, calling, Peru, captive

Roy Mangersnes / Wild Bolivian / Peruvian Squirrel Monkey (Saimiri boliviensis) in tree. Madidi National Park, Bolivia.

Roy Mangersnes / Wild Bolivian / Peruvian Squirrel Monkey (Saimiri boliviensis) female carrying young on her back. Madidi National Park, Bolivia.

Kevin Schafer / Central American / Red-backed squirrel monkey (Saimiri oerstedii) mother carrying baby on her back, Costa Rica, Vulnerable species

Michael & Patricia Fogden / Black-crowned Central American Squirrel Monkey (Saimiri oerstedii) male in rainforest, Costa Rica

Gerry Ellis / South American Squirrel Monkey (Saimiri sciureus), Monkey Island, Amazon Basin, Brazil

Pete Oxford / Common squirrel monkey {Saimiri sciureus} Manu NP, Amazonia, Per

Pete Oxford / Squirrel monkey {Saimiri sciureus} investigates camera. Amazonia, Ecuador

Pete Oxford / Common squirrel monkey {Saimiri sciureus} Amazonia, Brazil

Laurie Hedges / Slow motion shot of three Common squirrel monkeys (Saimiri sciureus) interacting and grooming, Amazon, Brazil. Captive.