The Atlantic Forest of Brazil is one of the richest habitats on earth, being named as one of the five most biodiverse areas ('biodiversity hotspots') on the planet. Its original extent may have exceeded 150 million hectares, mostly as a narrow strip of forest stretching more than 1000 km along the coast of Brazil. Yet little of this forest has survived, and when it has, it is mostly as small isolated non-viable fragments. Less than 20% of the original forest extent is protected.

Brazil contains many more primate species than any other country – and many of them are restricted to the Atlantic Forest. One of them is the Woolly Spider monkey or muriqui. It is endemic to the Atlantic Forest and is the largest monkey in the neotropics. There are two closely-related species of muriqui, both threatened with extinction. This organization is supporting attempts to conserve the Southern Muriqui (Brachyteles arachnoides), of which less than 1200 individuals are known from any part of its original range. The monkey lives naturally at low density with large home ranges.

Many surviving individuals live in fragmented habitats subject to hunting with the possibility of the gene flow required from their long-term survival. The last remaining substantial tract of Atlantic Forest is in Sao Paulo State, protected in part as the Carlos Botelho State Park, a World Heritage Site. The last population of any size of Southern Muriquis (more than 500 individuals) lives inside the park.

The Carlos Botelho Park and surrounding forested areas face challenges from hunting pressure and threats such as palm harvesting.