This is one of my favourite new subjects I'm working with at Khao Kheow Open Zoo, a Golden-Headed Lion Tamarin that somehow ended up here in Thailand.
Golden-Headed Lion Tamarins are an unfortunately Endangered species of New World monkey endemic to Brazil; those still remaining in the wild live an arboreal (tree-dwelling) life in areas of Brazilian rainforest to the east in the direction of the Atlantic Ocean. The average weight of adults is 900 grams (2 pounds), body length about 30 cm (12 inches), though their tails alone can measure up to 45 cm (17 inches).
In their native habitat, Tamarins generally live in family groups ranging in size from 2 to 11 individuals, preferring to keep to themselves and aggressively defending their territory from others.
Sadly and somewhat incredibly, their native home in the Bahia forests of Brazil has been reduced in size to only 2%; farming, ranching, mining and urbanisation having eaten up the other 98%! Needless to say, the Tamarin's greatest threats are mankind and ever-increasing loss of natural habitat.