[3][7][8] The golden lion tamarin gets its name from its bright reddish orange pelage and the extra long hairs around the face and ears which give it a distinctive mane.

The golden lion tamarin has a very limited distribution range, as over time they have lost all but 2%–5% of their original habitat in Brazil rain forest.

Tamarins live along the far southeast border of the country in the municipalities of Silva Jardim, Cabo Frio, Saquarema, and Araruama.

[17][18] By frequently moving their sleeping nests around, groups minimize the scent left behind, reducing the likelihood of predators finding them.

The golden lion tamarin tends to be active earlier and retire later in the warmer, wetter times of the year as the days are longer.

[20] The golden lion tamarin has a diverse, omnivorous diet consisting of fruits, flowers, nectar, bird eggs, insects and small vertebrates.

[17][18] The golden lion tamarin uses its fingers to extract prey from crevices, under leaves, and in dense growth; a behavior known as micromanipulation.

Mating is at its highest at the end of the rainy season between late March to mid-June and births peak during the September–February rains.

[33] A survey conducted in 1992 found the number of wild population of golden lion tamarins to be 562 individuals in 109 groups.

The predators make those sleeping sites, which are mainly tree holes (about 63.6%), larger in order to attack the golden lion tamarins, sometimes wiping out the entire family.

A smaller percentage of canopy coverage allows the golden lion tamarins to detect the predators faster, and being surrounded by other large trees allows them access to escape routes.

[33] Due to degradation of their habitats, there are fewer trees that can support entire social groups and some have to resort to using bamboo (17.5%), vine tangles (9.6%), and bromeliads (4.7%) as a sleeping site, making them more susceptible to predators.

Golden lion tamarins also scent mark their den holes, so they can quickly return to them in the afternoon time when predators are most active.

While excessive scent makes it easier for golden lion tamarins to find their sleeping sites, it also helps predators locate their prey.

Moreover, increased deforestation has decreased habitat space, providing predators easy access to their prey, causing a decline in the golden lion tamarin population.

[35] Threats to the golden lion tamarin population include illegal logging, poaching, mining, urbanization, deforestation, pet trading,[36] infrastructure development and the introduction of alien species.

[38] The species was listed as Endangered by the IUCN in 1982,[3] 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.

Because of the extensive habitat loss of the golden lion tamarin, the wild population reached endangered status in the early 1980s.

Beginning in 1983, there has been a huge effort on behalf of scientists and conservationists to introduce captive-born golden lion tamarins back into the wild.

When the tamarins are reintroduced in Poço das Antas Biological Reserve, they require a large amount of post-release training and veterinary care.

[40] Secondly, in an effort to save the golden lion tamarins from extinction, some of the golden lion tamarins have been removed from small, isolated unsafe forests and placed into a larger, protected forest; specifically they were moved to União Biological Reserve and Poço das Antas reserve.

[42] Despite the challenge of illness, the forty-two translocated golden lion tamarins' population grew to over 200 in União Biological Reserve.

However, deforestation of Atlantic Forest for commercial purposes, predation, and capture of the golden lion tamarins for animal trade and sale as pets has limited their population to about five municipalities across Rio de Janeiro.

The exposure to predation not only affects the juvenile tamarins but the adults as well, since it has been observed that play happens in the center of the group for protection of the young.

[46] With delay breeding, the decrease and shortage of territory puts pressure on golden lion tamarins to disperse in order to find necessary resources and areas suitable for their survival.

[47] A 2016-2018 yellow fever epidemic in southeastern Brazil had a significant impact on the golden lion tamarin population, reducing it by 32% to approximately 2,516 individuals.

The tamarin population faced increased losses in forest areas that were of a larger size, with fewer edge zones and greater connectivity, all of which could create conditions conducive to the presence and spread of mosquitoes that transmit yellow fever.

The cause of this decline was attributed to human activities, such as the expansion of the BR-101 highway, which brings a constant flow of traffic into the area.

Researchers noted that the rapid spread of the disease across Brazil, from north to south, was due to human mobility, as infected people carried the virus with them.

[49] In response to the epidemic, Brazilian scientists created a customized yellow fever vaccine specifically for golden lion tamarins.