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.

Habitat and Range
sign for Poco das AntasGolden lion tamarins inhabit the Atlantic coastal forest of Brazil. In Poço ("POH-so") das Antas, they prefer swamp forest, which contains many vines and bromeliads, and has a high density of fruit and animal foods. Because all of this land has been logged in the past, we don't know what kind of habitat GLTs originally preferred. Presumably they preferred a humid, closed canopy forest with many vines, bromeliads, and other epiphytes. The closed canopy and tangles of vines provide easy arboreal pathways and protection from aerial predators. The bromeliads host many insects and small vertebrates that are important tamarin foods. They are also an important water source.

GLTs sleep in tree holes, which are used for heat conservation and protection from nocturnal predators.

tamarin in a treeGolden lion tamarins are omnivorous, feeding on fruits, insects, and small lizards. GLTs actively search crevices, bark, bromeliads, and other hiding places for their prey. They use their long, slender fingers and hands to probe into these areas, a behavior called "micromanipulation."

golden lion tamarin eating bananaIn zoos, GLTs are fed fruit (bananas, apples, and oranges), canned marmoset diet, mealworms, and crickets. They supplement their planned diet with cockroaches, mice, and other uninvited guests that aren't quick enough to escape.

tamarin in a treeHawks and other raptors, cats, and large snakes are the main predators of GLTs. Data on predation are difficult to obtain. The tamarins give alarm calls in response to strange and/or threatening stimuli. They have a particular alarm call for large birds overhead. When that call is made, the animals head for the trunks of the trees or sometimes just let themselves fall to the ground. The alarm call and the response seem to be genetically "hard-wired." Zoo born animals that have always lived inside make the call and respond appropriately when birds fly over.

Social Behavior
In zoos, GLTs are kept in family groups. In the wild, groups are small (two to nine animals) and usually consist of one breeding adult of each sex and younger animals. The group members could be related (a family group), but transfer of animals between groups has been seen and may be quite common.

Tamarin groups actively defend a territory against other GLTs. Territories average 40 hectares (about 100 acres). The defense of a territory is accomplished through vocalizations and scent marking during ritualized group encounters. Actual fighting does not occur.

Occasionally more than one adult male (or, less commonly, more than one female) will breed in a group. Whether this represents a transitional situation, an alternate reproductive strategy based on cooperative rearing of infants, or just variation in tolerance between adults is unknown.

In captivity aggression occurs between animals of the same sex, especially between adult females. Mothers have been known to attack their older daughters, resulting in the death of one or more animals if they are not separated. Males appear to be more tolerant of each other, but will fight on occasion.

Births are usually twins. Infant care is cooperative. All members of the group will carry an infant, with the adult male commonly doing the largest share. The mother only takes the babies to nurse them. Since a set of twins might weigh as much as 15 to 20 percent of the mother's weight, she can use the help.

Young animals benefit from their experience with younger siblings. Males and females with previous caregiving experience as youngsters are much more likely to successfully raise their infants from the start. Pairs without prior infant experience often lose several sets of infants before they become competent parents.

Food is shared on occasion. Sharing is both passive (tolerated stealing) and active (offering food). Usually the food goes from older to younger animals. Often young animals will make a rasping noise (known as an infant rasp) as they try to take food from another animal.

GLTs retire at dusk and sleep until after sunrise. The adults are the first out of the holes in the morning and the last to enter at night. At zoos, they sleep in nestboxes. If nestboxes are provided in reserves or outdoor zoo exhibits, GLTs will always sleep in one.

Other GLT Facts
Gestation length: 126-130 days
Time to weaning: 90 days
Age at sexual maturity: 18 months
Life expectancy (in captivity): about 8 years for animals that survive past the infant stage—40 percent of infants die before 1 year.
Longevity record: 31 years

Several photos on this page were taken by James M. Dietz, University of Maryland, and are used with permission.