It is the southern extremity of an ecoregion defined by the conservation organization WWF as the Southwestern Amazon Rain Forests. Covering an area of more than 200,000 square miles across western Brazil, northern Bolivia, and southeastern Peru, this mosaic of tropical forests, savannah, and snaking rivers is one of the last wildlife paradises. The region contains some the world's greatest diversity of freshwater fish, birds, and butterflies. Animals rare in most parts of their range still thrive there, including jaguars, harpy eagles, giant river otters, myriad primates, and macaws.

WWF has been active in the region for more than 20 years, working with other organisations to set up protected areas and conserve the region's natural resources. In 1973, WWF's work in Manu, Peru, resulted in the 1973 designation of Manu National Park, one of the most biologically diverse parks on earth. Since then, many other projects have arisen, aimed at saving these invaluable wilderness areas through conservation and sustainable development.

Although much of the southwestern Amazon remains forested, pressures on these resources are growing, and many of the border areas where Fawcett once roamed are under threat. Networks of logging, mining, and other roads have cut through the forests, bringing in their wake large numbers of settlers. Farms, pastures and lumber operations have begun to transform what was once a hidden, remote world. Some of the area's pristine rivers now carry substantial amounts of mercury, which flushes into the water from gold mining operations, and upstream deforestation has led to increased silting, affecting river courses and aquatic life.

Percy Fawcett is perhaps most famous for finding and describing the Huanchaca Plateau in 1910. He later shared details about the bizarre landscape with famous author Sir Arthur Conan Doyle, telling him of the table-top plateau and walls of forest that rose 1,800 feet above the surrounding wilderness. His description apparently helped to inspire the dinosaur-infested setting for Conan Doyle's novel The Lost World.

Today, the Huanchaca Plateau appears as it did in Fawcett's day, rising above extensive forests and protected within Bolivia's 1.6-million-hectare Noel Kempff Mercado National Park. But not far away, just across the Brazilian border, the scene now is very different."While on the Bolivian side, the national park leaves the Huanchaca Plateau and surrounding forests essentially unaltered by human activities, crossing the Rio Verde one finds cows, cows and more cows," says Chelsea Specht, WWF Ecoregional Coordinator for the Southwestern Amazon.In recent years, timber rustlers from nearby areas entered the park and illegally forested mahogany and other hardwoods, but this activity has declined as a result of diligent patrolling and strict enforcement of forestry laws by park guards.

It is a similar story on the Madidi River in northwest Bolivia, where Fawcett's raft shot through rapids and plunged 20 feet over the edge of a waterfall. Today, the Madidi and surrounding forests remain remote and roadless. However, just east, the main road between La Paz, the largest city in Bolivia, and Riberalta, a small frontier town in the northeast has provided a conduit for highland settlers to move into the Amazon, and a road that will ultimately bisect Madidi National Park is under construction.

Planning ahead of potential habitat destruction, WWF, with funding from USAID, is working with local partners to string together critical habitats via the "Amboro-Madidi Ecological Corridor." Covering nearly five million hectares, this wildlife corridor will connect sustainably logged and hunted areas and protected areas in Bolivia, stretching from Amboró National Park in the south to the Madidi park in the northwest.

Eventually this corridor will be connected to the protected areas of southeastern Peru, extending to the Manu National Park and Reserve. While drawing up a management plan for the corridor, WWF and its partners are seeking long-term involvement from government agencies, non-governmental organizations and local landowners.

Other conservation efforts are underway near in the far northwest corner of Bolivia, near the Rio Acre, where Fawcett once shot an anaconda he claimed to be 62 feet long - though anacondas rarely grow longer than 20 feet. An indigenous group, the Yaminahua-Machineri, wants to work with WWF to develop a conservation strategy for the community that relies on sustainable harvest of local plants and animals. It is hoped to establish a nature reserve that will be used for managed hunting, while protecting habitat for a dozen or more primate species.

Elsewhere, WWF is working with the Universidad Amazonica del Pando and independent scientists to create a primate reserve in an area currently designated as a forest concession. The plan is to encourage the logging company to designate part of its concession as a protected area - the Tahuamanu Wildlife Reserve - in exchange for technical and logistical help in attaining certification for its forest products. Certification will help ensure a wider market for the concession's timber, while providing assurance of sustainable management and minimum impacts within the harvested acreage.

Although the world's tropical forests and their wildlife riches are rapidly dwindling, the southwestern Amazon remains an area of great hope. WWF and its partners will continue to work hard to ensure that - unlike the adventurer who dedicated his last years to their exploration - the forests of this incredibly diverse region never vanish.

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*Howard Youth is an environmental journalist based in Washington DC, USA.