The golden marmoset is restricted to a small geographic range in the Brazilian state of Rio de Janeiro, between the Itabapoana and Paraíba do Sul rivers. Its natural habitat is the Atlantic coastal rainforest ('mata atlântica'), which has been undergoing heavy deforestation since the arrival of the first European settlers. It has been estimated that nearly 90% of the original coastal forest in the state of Rio de Janeiro has been lost. The remaining fragments are often small and isolated, making them more susceptible to the effects of habitat fragmentation. Habitat loss and fragmentation result in the decline of the golden marmoset populations by reducing the availability of food, increasing the susceptibility to predation and diseases, and limiting the dispersal and gene flow between groups.
Hunting and illegal trade
The golden marmoset is prized as a pet due to its small size, beautiful coloration, and docile nature. This species has been targeted by poachers for the pet trade, even before it was listed as endangered. The illegal trade of golden marmosets is a significant threat to the species, as it can result in the depletion of wild populations and make it harder for conservationists to track and monitor their numbers.
Climate change
Climate change is also expected to negatively affect the golden marmoset. The species' current range could become unsuitable due to changes in temperature and precipitation, and the availability of food resources may decline. Fragmentation of the habitat could further exacerbate the effects of climate change by reducing the ability of the species to adapt and move to more suitable areas.
The combination of these threats has resulted in the classification of the golden marmoset as critically endangered by the IUCN. Conservation efforts are being made to protect the remaining populations of this species, including the creation of protected areas, habitat restoration, and measures to reduce hunting and the illegal trade.