SILVA JARDIM, Brazil -- Three tiny flaming orange monkeys crouched on a tree branch, cocking their heads as if to better hear the high-pitched whistles and yaps that came from deep within the dense green foliage. Then they answered in kind, rending the morning with their sharp calls and cautiously greeting each other in the forest.
That the cries of Brazil's endangered golden lion tamarins should fill the air at all on a recent afternoon was cause for celebration, the result of one of the world's most inspired species restoration efforts. In fact, that campaign has transformed the lush forest where the monkeys live and has become a model widely cited for saving other animals.
"There is no question in my mind that the golden lion tamarin is one of the best examples of international collaboration anywhere in the world," said Russell Mittermeier, president of environmental group Conservation International and chair of the International Union for Conservation of Nature's group on primates. "I cite it every couple of weeks. This is how you do this kind of thing."
Saving the squirrel-sized monkeys, which sport a lush coat and foot-long tail, became a passion for everyone from international animal aid groups to Brazilian conservationists. It also brought in people living in the area, from well-off landowners to farm workers, who learned how to make a living from growing the trees that the monkeys depend on to survive, researchers said. Its population has grown from just hundreds four decades ago to 1,700 in Rio de Janeiro state.
Now the tamarin is in the running for mascot in Brazil's 2016 Olympics, and the next step to ensuring its survival might be helped along by another Olympic project: the state's promise to plant 24 million trees, enough to absorb the greenhouse gases generated by the vehicle traffic, construction and other activities of the games. That would help further restore the swath of species-rich Atlantic forest that once covered much of Brazil's coast, and ensure the tamarin population has enough room to thrive.
"It's an ambitious goal, and it won't be easy," said Marcia Hirota, of the environmental group the SOS Mata Atlantica Foundation, aimed at restoring the forest. "It's a challenge, but Rio has already cut down on deforestation. With this kind of public policy, Rio can become an example for other states that are in a more critical situation."
For centuries, the little golden monkeys had been exported as pets and as exhibits in zoos around the world, with even Louis XV's chief mistress buying one for the French court. Its popularity became key to its survival: Even as the species faced threats in Brazil, enough monkeys were living abroad in places like in the Smithsonian Institution's National Zoo to usher in its rebound. Rio state is the only place in the world where the tamarins live in the wild.
The first push to save the tamarins began in the early 1970s, when a Brazilian researcher found their once-teeming numbers dwindling as cities and farms ate into the forest.
Once the alarm was sounded, researchers in Brazil and abroad began working together on a labor of love that would consume decades. Their first goal: learning how to encourage the monkeys to mate.
The rescuers then turned to their most challenging task -- reviving the forest, which covers Brazil's most populated region, and gradually reintroducing the monkey into the wild, explained Mittermeier, who has been part of the effort since he was a student in the early 1970s.
Even in the first few years, the effort broke new ground: The Poco das Antas biological reserve in Rio state, set up to preserve the tamarin's habitat, was the first of its kind in the nation. It provides the most stringent form of protection possible, setting aside public land but closing it off to visitors, to be used only for research and education. When the reserve began in 1974, roughly 100 tamarins lived in the area. Now there are 250.
By 1983, researchers started introducing the golden monkeys into the wild only to watch with heartbreak as the naive zoo-bred animals met tragic deaths because they failed to recognize panthers and other predators or find shelter or food. Nearly three decades later, the population has multiplied in all of Rio state, with each tamarin an expert in identifying the 150 types of fruits, berries, shoots and insects it can survive on, said Andreia Martins, field coordinator for the Golden Lion Tamarin Association. The association is the main Brazilian group working to save the monkeys.
"If you're lost in the forest, follow the tamarin," she said. "They'll always find food."
The next step should be within reach: raising the golden lion tamarin's population to around a sustainable level of 2,000 or more.
The main obstacle, the sheer lack of habitat, is where the Olympics come in.
Brazil's coastal Atlantic forest is one of the world's biodiversity hotspots. About 2,200 different birds, mammals, reptiles and amphibians, including 60 percent of the country's threatened species, make their home in this jungle, one of the most diverse ecosystems on the planet and also one of the most threatened.
The monkey is an umbrella species whose protection ensures that dozens of other species in the region have a chance of survival, including the endangered maned three-toed sloth and the wooly spider monkey.
People depend on it as well. The Mata Atlantica forest, as it is known in Brazil, encompasses the nation's biggest cities, Rio de Janeiro and Sao Paulo, and about 70 percent of the country's population. Seven of Brazil's 10 biggest cities depend on its rivers and springs for water and electricity generation.
That kind of development has reduced the luxuriant jungle to 8 percent of its original 3.2 million acres (1.3 million hectares). About 80 percent of the land is privately owned, and it's expensive, much of it taken up with ranches and farms.
Conservationists say the monkeys need about 61,800 acres (25,000 hectares) of protected, interconnected forest for the species to thrive on their own. So far, they only have 40 percent of that required land to live on.
Expanding the forest comes with own challenges, first off finding quality seeds from the diversity of plants in the region and then sprouting those seeds into healthy shoots.
The rescuers have recruited people living in the forest, many of them former field workers who used to harvest vegetables, and trained them to recognize native trees, select seeds and monitor their growth, creating seven small-scale nurseries set up by locals.
For Marlene de Oliveira and her sister, the nursery business was a godsend. After decades of back-breaking work harvesting manioc root, they're now the proud owners of a sturdy wood-frame, mesh-walled nursery near the reserve for which their shoots are destined. In their first year, they produced 14,000 shoots of dozens of species.
The county where the de Olveiras work has become the nation's leader in private reserves, with 22. The landowner voluntarily grants the legal protection, but once a plot gets the designation, it's binding: The forest can never be cut down, even if the ground under it is sold.
"I used to think this was a funny idea, planting trees," said de Oliveira, through a wide, gummy grin from which most teeth were missing. "I used to wonder, why not plant food? What good is this to anyone? Now I see it's good for the monkeys, and good for everyone."