hen on location in the Amazon for a shoot — five days in one indigenous community, five days in another — National Geographic photojournalist Charlie Hamilton James sets about disarming photographic subjects within a few hours of his arrival. At six foot four and boasting a native Brit’s pale complexion, he can’t hope to blend into the background. So on a recent visit with Awá nomads in Brazil — among the world’s most isolated and threatened indigenous people — he pulled out his drone.

“I take still photos with drones; I don’t film with them,” he explains a day after returning home to Wyoming from Mozambique. “Drones were one way of getting into the Awá community fast. The whole village turns out to watch the drone. Everyone’s crowding around to look at the screen, because they’re looking at their village from 200 feet up. They’ve never seen that.”

Many of his images for October’s cover story about isolated tribes in Brazil and Peru are sobering, such as one of volunteer Guajajara forest guardians posed with fatigues and guns. Others capture moments of ease and familiarity; the most endearing photos depict Awá women clutching pet turtles as they bathe in a river, and children with pet saki monkeys on their heads. Yet they are devoid of sentimentality.

“When I was taking those photos in the river, washing tortoises, within 20 minutes everyone completely ignored me. And I’m wandering around in my underpants,” Hamilton James says. “I’m taking so many pictures that they just zone out with me, or I’m laughing with them. That’s what it’s about: finding common ground that we can laugh about together. When you do that as human beings, you make a connection. It’s the same anywhere in the world.”

The mordantly witty photographer, who will soon be photographing sea otters around Monterey, plans to weave stories like that into tonight’s talk at Caltech. “I Bought a Rainforest” chronicles his experiences (also covered in a 2014 BBC-TV documentary) purchasing 100 acres by Manú National Park, a UNESCO-recognized Biosphere Reserve and World Heritage Site in Peru, and discovering he had tenants: illegal loggers and a cocaine farm. His stories elicit chuckles but, like his stunning photography, the purpose they serve could not be more serious. After witnessing ecosystem degradation for almost three decades, the fortysomething photojournalist is well positioned to champion the necessity of preserving the Amazon.

When this writer spoke with him for another publication two years ago, he made the practical point that expecting indigenous families who live in the Amazon to never cut down a tree to feed their family is “kind of ludicrous.” It’s tricky because the world depends on them to guard the rainforest, which — like indigenous communities — remains imperiled by illegal logging and narco trafficking. (The recent election of far-right, pro-business candidate Jair Bolsonaro to Brazil’s presidency bodes ill for the Amazon and its indigenous protectors; Bolsonaro infamously declared, “It’s a shame that the Brazilian cavalry wasn’t as efficient as the Americans, who exterminated their Indians.”)

For Westerners who enjoy health and food security to tell indigenous communities “hands off” the natural treasure they guard while subsisting in extreme poverty is like condemning them to join Tantalus beneath the tree with low-hanging fruit — forever within reach, never attainable. The global conflict between poverty and conservation requires a global, non-ideological resolution. “Conservation,” Hamilton James said then, “is a bourgeois concept.”

“That’s still my principal mantra in conservation,” he says now. His recent journey to Mozambique’s once war-torn Gorongosa National Park suggested a potential solution: empowering people who live in buffer zones around such parks with employment and “masses of education” (principally of women) so they are invested long term in reducing pressures on the park’s natural resources. Crucially, tech billionaire Greg Carr’s foundation helped bankroll Gorongosa’s restoration.

“It’s one of the more progressive and sensible environmental conservation projects going on in the world at the moment,” Hamilton James says. “It’s an extension of what I’m seeing in the Amazon.”

Asked what he deems the most urgent and underreported global environmental story, he points to cattle. Since 1990, hundreds of thousands of square miles of the Amazon have been burned, mostly for cattle farms; the nomadic Awá, who forage and hunt, are losing food sources and territory to fires set by illegal loggers in their supposedly protected refuge.

“We took on plastic this year as a sort of global environmental zeitgeist; I think cattle needs to be brought into the frame,” he says. “If you look at a lot of the world’s environmental problems, not just with global warming, which cattle contribute to substantially, but with the loss of predators and loss of ecosystems and issues in the Amazon — a lot of it comes down to cattle.”

Even isolated Awá have rock band T-shirts, and Hamilton James says teenage boys and younger men often carry cellphones. That creates cognitive dissonance for outsiders trying to understand whether they are “uncontacted,” or if their outposts are like Native American reservations in the US.

“The older Awá, many of them can’t speak Spanish, so their connection is much more tenuous to what you’d call modern civilization,” Hamilton James explains. “But that said, most of those pictures were taken within an hour and a half of a big town. That’s what’s really weird about it. You’ve got these reserves, these islands of forests in this sea of development, and there are isolated people living in there who have no contact with the outside world. And then you have the Awá that I photographed, who are in initial contact, who are kind of a bridge between the outside world and those more isolated people. It’s so bizarre that they live so close to modern civilization.”

“I Bought a Rainforest”: National Geographic Live presents Charlie Hamilton James at Caltech’s Beckman Auditorium, 1200 E. California Blvd., Pasadena, at 8 p.m. Thursday, Nov. 15; $37 general admission/$10 youth. Info: (626) 395-4652. charliehamiltonjames.com, Caltech.edu, video.nationalgeographic.com/video/ng-live