The Eco Warriors
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A few hundred feet about the Hudson's eastern bank, Ford's helicopter hovers atop a square of land jutting into the river in a clearly artificial way – clearly artificial, at least, from this altitude. "This is a yacht club," explains Seggos. "A while back, they illegally filled the riverbank to make themselves some new space. We also have an informant telling us that oil drums and old appliances were being dumped here."

"This was a case referred by a citizen watchdog," adds Matthiessen.

"Looks like they filled in about an acre, huh?" says Ford, and the frown returns. The Hudson may be 306 miles long, and an acre just an acre, but it's this type of thing, this gnawing away at nature, that annoys him. "We keep pulling out pieces of the puzzle," he tells me later, "and expecting it to heal itself." The Hudson may be hemmed in and its banks built up, but its current still runs wild.

Wildness, on water and land and in the sky, has beckoned Ford since his childhood. As a boy growing up in Morton Grove, Illinois, Ford retreated from neighborhood bullies – who liked to roll him down a hill – into the wildish edges of his subdivision, which sparked his early ambition to be a forest ranger. But after flunking out of Wisconsin's Ripon College, Ford headed to California, where he flirted with acting and then went with carpentry, which provided him a living for nearly a decade. Then came American Graffiti (1973), then Star Wars (1977), and you know the rest. Never comfortable with fame, never at ease with Hollywood's tacky apparatus, Ford found refuge in his Wyoming ranch, and then, later, in the cockpits of his plane and helicopter, where, he says, he can keep "from thinking about anything but flying." That and the wide earth below him.

"There's still time left to hold the line," he tells me, "to save sufficient biodiversity, to preserve what's necessary for nature to function." Does it ever frustrate him, I ask – flying over some denuded stretch of clear-cut forest? "No," he says. "Never. People don't need to despair. They need to know that there are solutions – good, practical solutions – and they need to keep up the good fight."