The golden lion tamarin (Leontopithecus rosalia) also known as the golden marmoset, is a small New World monkey of the family Callitrichidae. Native to the Atlantic coastal forests of Brazil, the golden lion tamarin is an endangered species with an estimated wild population of approximately 1,000 individuals spread between 3 different locations along southeastern Brazil, and a captive population maintained at approximately 490 individuals among 150 zoos.
Threats to the golden lion tamarin population include illegal logging, poaching, mining, urbanization and infrastructure development and the introduction of alien species. The species was listed as Endangered by the IUCN in 1982, and by 1984 the National Zoological Park in Washington, D.C. and the World Wide Fund for Nature, through the Golden Lion Tamarin Association, began a reintroduction programme from 140 zoos worldwide. Despite the success of the project, the IUCN classification rose to Critically Endangered in 1996. By 2003 the successful establishment of a new population at União Biological Reserve enabled downgrading the species to endangered, but the IUCN warns that extreme habitat fragmentation from deforestation means the wild population has little potential for any further expansion. In an attempt to curb the golden lion tamarin's precipitous decline, several conservation programs have been undertaken. The intent is to strengthen the wild population and maintain a secure captive population in zoos worldwide. The survival rate of re-introduced animals has been encouraging, but destruction of unprotected habitat continues.