Golden lion tamarins are small orange-yellow monkeys, weighing 500 to 600 grams. They live in the heavily populated coastal region of Brazil, where less than two percent of the forest remains.

They are endangered because their habitat has been fragmented into small, unconnected areas, each area only capable of supporting a small number of groups. Without intervention by the National Zoo, other zoos, organizations, and the Brazilian government, inbreeding would soon lead to the local extinction of many of these small populations of tamarins, and eventually of the entire species.

About 1,500 golden lion tamarins (GLTs) live in the wild, most in or near the Reserva Biologica de Poço das Antas in the state of Rio de Janeiro. About 450 live in zoos worldwide