The golden is the best known to science, first documented by a member of Magellan's 1519 expedition. Darwin also took an interest in the brightly colored primate. Knowledge of their existence led inevitably to their exploitation by man. Hunting, trafficking and habitat destruction has reduced their range along the Atlantic coast of Rio de Janerio state. Now they live in forest fragments in the Rio Joao river basin between towns in the area. One of the first population counts in 1969 totaled 600 tamarins. By 1977 that number was reduced to between 100 and 200 individuals living in the wild. An alarm was sounded by primatologists concerned for their extinction.
In the fifty years since then, golden tamarins have rebounded due to concerted conservation efforts, including captive breeding, and the creation of several protected reserves. These efforts have also helped preserve forest tracts, but they are fragmented. An assessment of the tamarins conservation status in 2005 concluded that for tamarins to survive one hundred years into the future, there needs to be at least 2,000 tamarins living across 62,000 acres of connected forest by 2025. Brazil now has that many tamarins and forest hectares, but the problem is connecting these habitats. As exclusive forest dwellers, tamarins will not cross pastures to reach another forested area. When lion tamarins reach about 2 years old they are expelled from their troop to fend for themselves, and find a corner of the forest to call their own. Their territory is about 125 acres, which they defend vigorously against outsiders. An expelled lion tamarin may find himself at the edge of a forest fragment with nowhere to go except down where he is very vulneralble to predation.
The laregest block of intact Atlantic forest is the twenty thousand hectare tract in União Biological Reserve and the Aldeia Velha area of Silva Jardim municipality. The forest is bounded by a major freeway leading into the city of Rio de Janero. Fortunately a wildlife crossing was built, which helps in the dire situation. When BR101 was widened, a lengthy legal struggled ensured over the required mitigation structures: ten treetop passage ways, fifteen underground tunnels and one vegetation covered viaduct. In 2020 the planted bridge was inaugurated. Tamarins will not be able to use it effectively until the planted trees are big enough for them to use. Not a perfect solution, but a viable start to connecting the forest.
Habitat fragmentation is not the only threat to lion tamarins. In 2017 yellow fever broke out, killing a third of their population, about 1200 hundred individuals. In the Poco das Antas reserve only 33 of the 380 tamarins that lived there survived the disease. The solution was obvious: innoculate both humans and primates. The human yellow fever vaccine has been available for eighty years. But a primate version was not available in 2017, until it was developed by the Oswaldo Cruz Foundation, Brazil's leading biomedical reserch institute and tested on captive golden-headed tamarins Vaccination of golden lion tamarins began in November 2020 with the goal of vaccinating 400 tamarins by the end 2022. So far, 200 hundred have gotten their shot. The golden lion tarmarin is the first non-human species in the world to be vaccinated against yellow fever. Next post: the return of the black tamarin.