MOISES, WHO IS 42 AND A DECEPTIVELY strong 5-foot-3 and 135 pounds, met me at the airport in Iquitos wearing baggy denim cutoffs, a T-shirt that read "I Survived an Amazonia Expedition," and a foam-domed baseball cap of the sort an American might associate with the interstate trucking profession. Tufts of curly black hair protruded below his hat, as did a set of smallish, jug-handle ears. We took a motorized ricksha—a three-wheeled motorcycle conversion that serves as the typical taxi in this steamy jungle city of half a million—to the Amazonia Expeditions dock. From there we powerboated three or so hours up the Amazon and another hour up the Tahuayo River to the lodge, which stands alone three-quarters of a mile from the tiny village of El Chino and has no electricity. The structure is glorious—a warren of cedar walkways on stilts 10 to 20 feet above the river floodplain; 17 high-ceilinged, open-beam, screened-in bungalows; a huge dining hall that looks out on a slow-moving bend of the river. The plan was to spend three days at the lodge—gawking at monkeys, fishing for piranhas, and napping in hammocks—before heading into the jungle with Moises, his apprentice Josias Tello, and photographer Bill Hatcher.

Normally, Moises Chavez's job as chief guide at Tahuayo Lodge is to run the daily activities: guided hikes, canopy climbing, and other outings in search of red-and-green macaws and pygmy marmosets—the world's smallest primates. He might even show you a hoatzin, otherwise known as the dinosaur bird, a blue-faced, ornately-mohawked creature bigger than a turkey, whose closest known relative became extinct 36 million years ago. Though Moises comes across as intense, he's quick to produce a wide smile. Even during these first days, it was easy to see him as eerily in harmony with the rainforest, a jungle spirit who seemed to glide through its labyrinthine corridors, reading them as readily as I might the aisles of a Safeway.

He learned the ways of the rainforest growing up in Indian villages deep in the Peruvian Amazon, where his late father, Gerineldo Sr., worked for the Peruvian government as a teacher to indigenous tribes, accompanied by his Brazilian wife, Moises's mother, and his two older brothers. Moises was born in the Yagua Indian village of Huanana on the Napo River and attended school in the thatch-roofed huts that his father built, but he also participated in all the rites of growing up native. If Moises's pals were going spearfishing for dinner, he went too. If they were extracting strychnine from the curare vine for poison blowgun darts, he did likewise. When ill, he went to the local curandero, or healer. The kids spoke Spanish in the classroom and a mixture of Spanish and Indian dialects elsewhere. (Moises picked up his passable English later, working as a guide.)

The family lived with the Yagua for six years or so, but then Moises's father taught among other tribes, including the Huitoto, Bora, Ocaina, Secoya, and Ticuna—all in Peru's far-northern Loreto Department, between the borders of Ecuador and Colombia. Along the way, Moises picked up a wide range of skills, customs, and dialects, giving him a uniquely ecumenical understanding of the jungle and its people. Now it's difficult even for him to say where he learned what. "I'm all the time very curious as a boy, and live with other boys like animals," he explained. "I see when we hunt and fish how they move through the jungle like animals. I learn from my father, I learn from their fathers—but mostly I learn from the other kids."

Moises was 14 when his father became ill with Parkinson's disease, forcing the family to move to Iquitos so Gerineldo Sr. could receive medical treatment. Moises quit school, and together with his older brothers began working for Explorama, a large American tour company in the city. After further survival training during a short stint in the army, Moises returned to Explorama.

He'd been working there for ten years when a former researcher from the Chicago Zoological Society named Paul Beaver lured him away. Beaver was running wilderness camping trips from a base camp on the Yarapa River but wanted to open a lodge near the Tamshiyacu-Tahuayo Reserve. The two-million-acre area is a Pleistocene refugia, meaning it remained forested during the Ice Age and hence remains home to strange endemic species, such as red uakari monkeys and canids called bushdogs, that few Westerners have ever seen. The reserve contains greater mammal diversity than any like-size nook of the Amazon and greater primate diversity (15 species) than any wildlife preserve in the world. During the late eighties, the Rainforest Conservation Fund collaborated with local people of mixed Spanish and Indian descent who live in villages along the Tahuayo to thwart development and lobby for government protection, which was secured with the establishment of the reserve in 1991. Now it's a showcase tropical rainforest, seemingly a world away from the slash-and-burn madness of the Amazon forests of Brazil.

With Moises's reputation as a superb guide and teacher, Beaver opened Tahuayo Lodge in 1995. "I knew Moises's skill and attitude could help me create a competitive tourism program," Beaver told me. "I was like a struggling sports franchise willing to pay astronomical sums to a star player. I treated Moises as a free agent and persuaded him to come work with me."

Moises has still never been outside the Amazon Basin.