José Márcio Corrêa Ayres, a Brazilian zoologist who has been widely credited with saving the world's largest swath of protected rain forest, died March 7 in New York City. Ayres, who was 49, died of lung cancer.

At the time of his death, Ayres served as senior conservation biologist at the Wildlife Conservation Society, the global agency based at New York City's Bronx Zoo. But his most noted accomplishments were in Brazil, near the confluence of the Solimões (Amazon) and Japourá Rivers.

This was not far from the site where Ayres began his serious education into the biological diversity of the Amazon. As a young man, he had seen a white uakari monkey from the upper Amazon at a German zoo. He returned home to Brazil, embarrassed that he had never seen the animal in his home country and determined to learn more about his native environment. He bought a riverboat upstream in Manaus, put his family on board, moved into the river's upper reaches, and began a study of the uakari that brought him his PhD in primatology from Cambridge University in 1986. Appalled by the habitat destruction he saw around him, Ayres started a long campaign to bring protected status to the area.

The scientist battled and reasoned with bureaucracy, the resource extraction community and even some fellow environmentalists and researchers to create the Mamirauá Sustainable Development Reserve, Brazil's first such area, in 1996. Two years later, Ayres set up the adjacent Amanã Sustainable Development Reserve. Together, the reserves, plus Jaú National Park, produced the Amazon's largest environmental corridor — more than 22,000 square miles of seasonally flooded forest covering an area larger than Costa Rica.

The reserves provide habitat for thousands of types of birds, fish, land mammals, plants as well as Homo sapiens, a species often excluded from protected conservation areas. Ayres and colleagues worked closely with people living within the reserves, most of them rural Amazonians of mixed white and Indian blood known as caboclos, to plan the area's future.

José Márcio Ayres, known to friends and colleagues as Márcio, believed that local people must be involved in planning and managing such projects. To John G. Robinson, senior vice president and director of international conservation for the Wildlife Conservation Society, Ayres had "fundamentally changed the way Brazil thought about its protected area system.

"Before he came on board, the core way of thinking about protected areas was that protected areas and parks were areas where human beings were not allowed. A number of national parks were created, and people conveniently forgot that these areas were just chock-a-block full of people, in many cases, who were making their livings basically by exploiting natural resources."

The result of such policies, Robinson said, was that "the local people became totally disenfranchised from the national park system in Brazil. Basically what Márcio did was say, 'Hey: people are part of this landscape. And we can work with the people towards common interests so that together, we can actually make this park system functional.' And Mamirauá is in many ways one of the most functional national parks in Brazil, perhaps one of the most functional parks in the world, because the local people are very firmly behind the protection and conservation of wildlife, of natural resources, and so on, because they were built into it from the very start… And this has had a huge impact around the world."

Miguel Pinedos, a Columbia University researcher and Amazon native who has worked at Mamirauá since 1987, told The Scientist, Ayres proved that "you can do conservation without taking people from their communities. The way the local people look at conservationists is a very conflicted relationship. They see the conservationists as the ones who will help elephants, but they are also going to destroy the livelihood of the people. What Márcio did was he became a voice for these people who were already conserving the land."

Carlos Peres, who teaches at the University of East Anglia and researches human effects on protected Amazon reserves, remembers his friend Márcio as a fellow teenager and future scientist in Belém. "He was fondly known as Além da Imaginaçã o" — beyond the imagination — "and like many of us was a bit of an odd kid, often more interested in 'weird' things well ahead of his time than the usual pursuits of his peers," said Peres.

When Ayres was named a winner of the Rolex Award in 2000, he welcomed the recognition not for himself but for the programs he had created. "The better known the project," he said at the time, "the less likely that opponents or politicians can destroy it."

José Márcio Ayres was born February 21, 1954 in Belém, near the mouth of the Amazon, where much of his family still resides. He is survived by his wife, Carolina Diniz Ayres; two sons, Daniel and Lucas; a brother, Manuel and sister, Helena, and his parents, Manuel and Iza Ayres.