For a few days this month, America became a nation of bird-watchers. More than 3,000 dead black birds started raining from the sky shortly before the new year broke in Beebe, Ark., prompting widespread concern about ecological disaster, government conspiracy, and the Rapture. This was not the first time feathered creatures landed recently in public life. Birding, these days, is everywhere. In Jonathan Franzen’s best-selling novel, Freedom , paterfamilias Walter Berglund becomes a bird fanatic to conjure meaning in his drifting life. (Freedom’scover—maybe you have seen it?—sports a large, teed-off-looking cerulean warbler.) Annie Proulx’s new memoir, Bird Cloud , flatlines “into long descriptions of bird watching,” wrote the critic Dwight Garner. These next months, meanwhile, Princeton will publish three separate bird guides ; Steve Martin will star in a screen version of The Big Year (a tale of pan-continental birding); and the nation’s leading bird-art exhibition will turn 35. If American life is, as some people like to say, a tree of many branches, it is starting to seem a good idea not to stand beneath it.

What are we to make of the renascent birder? To the uninitiated, a bird-watcher’s motives can seem puzzling, if not downright suspect. Rising at vampiric hours, these people leave polite society behind to spend long stretches staring not at dazzling vistas or strange beasts but at birds—and often unexotic ones at that. They pack enough high-end equipment and field expertise to undertake a hunt but never touch their prey; the consummating act of birding is, at most, a picture snapped for private use and from a distance, in the manner of a pervert with a beach pass. Birding is the sort of hobby that seems like a front for something. Occasionally, it is. (Nathan Leopold, of Leopold and Loeb, famously claimed to be watching a Wilson’s phalarope instead of slaying a 14-year-old child.) Franzen links the rise of his bird-watching interest to his mother’s death and goes on to describe “a creeping sense of shame about what I was doing.” Proulx scoffs at other birders’ eagerness to keep “a list of birds sighted.” There’s a sense, amid these judgments, that to bird intensely is to dwell on something totally beside the point.

In fact, the re-emergence of bird-watching in the culture’s limelight is an ominous thing—though not because of anything the birder does. The hobby rose to popularity in the unrest of the nuclear era, and it points toward a looming fear of ecological apocalypse. This makes sense. For bird-watchers, who are trying to keep track of the natural world without leaving a trace—to conquer nature without smothering it—the struggle not to uncoil one’s strength destructively is constant. Birding is a steam valve for anxiety about nuclear-age strength and habits. Its prominence today can be seen as a measure of quiet alarm.

To bird seems ancient, but it was a product of industrial modernity. The first birders—as opposed to hunters or scientists—appeared in the late 19th century, partly as a result of a boom in the natural sciences (which helped flesh out the field of ornithology) and partly as a reaction against the new effects of manufacturing. In America, early on, Harriet Hemenway founded the Massachusetts Audubon Society to fight the industrial slaughter of local birds for hat feathers. But it wasn’t until Roger Tory Peterson, an American illustrator and bird enthusiast, published his Field Guide to the Birds in 1934 that modern birding came into being. Peterson’s work was comprehensive and accessible, and it offered enthusiasts an approach that didn’t require trapping or felling birds for close comparative study, as much previous work had. The book instead used visual, auditory, and habitat cues to distinguish species, letting the untrained birder work with precision from a distance. Birding became a popular science that left no trace—and that was seen to be a good thing. In one of the most quietly influential passages of his book, Peterson referred to birds as “sensitive indicators of the environment, a sort of ‘ecological litmus paper.’ ” This was the idea that made birding the great hobby, and alarm bell, of the nuclear age.

Birding took wing as a mainstream pursuit in the ‘60s by playing into that era’s anxieties. In 1962, Rachel Carson published Silent Spring , a landmark best-seller arguing elegantly and at length that DDT was ecologically lethal. She opened with the image of a lifeless world, marked chiefly by the absence of our feathered friends. (“The birds—where had they gone?” she wrote. “It was a spring without voices.”) Birds throughout heralded apocalypse: The death of western grebes marked eco-disaster at Clear Lake; sick birds in Detroit gave the first sign of environmental poison. The book made this de-birded world look like nuclear cataclysm. If something terrible was going to happen, birds seemed poised to give the first cry. In 1963, Alfred Hitchcock released The Birds , the paranoid tale of a small Bay Area town savaged by murderous flocks. Some viewers see it as an appeal to the same nuclear-age terror, with the birds now serving as antagonists. has observed, “Hitchcock’s last triumph is easily assimilated into the Cold War’s keep-watching-the-skies panic.”> Bird-watching increased nearly 300 percent in the two decades after 1960, according to data from the U.S. Department of the Interior. In 1967, Britain’s John Gooders published a servicey book called Where To Watch Birds , and it sold almost 250,000 copies.

Birding was also a hobby suited to the new American middle class—peripatetic, self-possessed, given to prelapsarian wistfulness. One of the most beloved birding memoirs of all time is Kenn Kaufman’s Kingbird Highway (1997), a seductive account of his time hitchhiking around the country as a teenager in the early ‘70s, exceeding the sighting record for a “big year” with 671 kinds of birds. The book is written in the errant episodic form of On the Road or Easy Rider , and, like them, it’s based on an idea of the American continent as a large, unharvested field of experience (in this case, experience of birds). But it also shows how birders’ competitive and broadening ambitions relied on transportation and technological growth. That trend continues. Today, there are crowd-sourced bird-mapping tools, birding packages that double as vacation getaways, birding blogs, birding iPhone apps, and remote-birding Web sites that don’t require watchers to be present in the landscape at all. A few old-fashioned birders may still practice their hobby in isolation with binoculars and field guides, but the birding community, these days, has moved on to gather, check, and share sightings across great distances using the fruits of technological industry and the jumbo jet.

A few days ago, I set out before dawn to watch birders practice their art in the middle of New York. Van Cortlandt Park is a 1,100-acre stretch of green land in the Bronx, and with its mixed terrain—open fields, wide groves, and wetlands cast among the footpaths and tussocks—it’s become something of a birder’s urban Mecca. Winter is a quiet time. A snow had come through recently when I arrived that morning, capping the branches white and smoothing out the fields. I passed two men running a black dog near the entrance. Then, until I met my guides, I was the only human being in sight.

A birder is a person who enjoys privileged aloneness—someone who, in other circumstances, might relish the idea of returning from a jog while you are still in bed. “If I weren’t doing this walk here, I would already have mapped my morning,” Andrew Baksh, my guide, said as we trotted down an icy path toward prime birding ground. He wore a navy-blue stocking cap pulled over his ears, a heavy parka, and an orange hiking backpack, and he lugged his spotting scope and tripod over one shoulder. It was barely 8 o’clock. Baksh’s profession is information technology, but since falling in love with the birds in his Queens backyard, he’s worked up both his expertise and his investment in the birding community. These days, he maintains a bird blog and does work for the New York City Audubon. He is interested, especially, in birding etiquette, the underlying tenet of which is to be as unobtrusive as possible. “This is a serious, serious hobby,” he said. “Some people don’t like to call it a hobby at all.”

I was out with Baksh and one of the park’s bird-loving rangers, Katy Boula, in pursuit of something known as the American coot. A birder in the park had first spotted the coot , a new bird for Van Cortlandt, on New Year’s Day. Since then, it had been observed in various locales. We’d hardly left to search for it when Boula whirled around midsentence and pointed excitedly toward the sky. “Oh, hawk!” she cried. “That was a red-tailed hawk!” A large bird banked and perched up in an empty tree. A bit later, we headed east, out to a pond. “Coots are a good bird for this time year,” Baksh said as we drew near. “That would have been very sought-after for the Christmas count. Of course, a greater white-fronted goose would have beaten everything.” He grinned as if this were a joke. I did, too. Then he nodded toward the water. “There go the Canadas.”

A large group of geese were out on the icy pond, beyond some trees, and we stopped on the trail to watch them. Baksh set up his tripod and spent several minutes peering through it, saying nothing. He was staring at the geese. I wanted to ask a question, but I talked instead with Boula, who showed me some pictures of coots in her Sibley Guide . Finally, Baksh spoke. “Yeah,” he said. “Nothing there.” I took a look through his scope. Through the lens, the geese looked strangely cinematic, sitting on the ice, vivid and near, with feathers flickering in the icy wind. I pulled back, and a bird cried out over the water.

“Wow, strong call.” Boula said. “Is that the Carolina wren?”

Baksh nodded. “It’s the Carolina wren.”

Boula showed me a picture of the Carolina wren. “Sometimes , you’re not going to see the bird. You’re only going to hear it,” she said. “With birding, it’s all in the little details.”

Generally speaking, there are four species of birder at large in the world. The first and least intimidating group includes those who see bird-watching as an endeavor roughly equivalent to Tuesday-night poker, volunteer gardening, or mah-jongg—an open-access hobby and a chance to connect regularly with friends. These people are frequently novices, and they tend to be extremely chatty in the field. (This seems eccentric if you are a birder.) Baksh counts himself among a second group, an autonomous cadre of enthusiasts who set their own schedules and often dwell on single bird groups or locales for stretches, like a book critic taking a month to read an author’s full oeuvre. Then there are the specialists. These people focus on one kind of bird obsessively and always, often with accompanying Web sites. Fourth are the listers, who chase birds to check them off a list. Some keep life lists (birds they’ve seen in their lives); * some keep year lists (starting anew every January); and others make up to-do lists by country, state, and so forth (certain New York City listers work by borough). There is, possibly, something compulsive in this approach. And yet the listers are the sexy ones, the intrepid jet-setters you may spy fleeing across the tarmac toting bags of optical equipment, trying to nail those last few birds, a continent away, before their deadline falls.

Baksh once got a taste of this excitement when a rare hermit warbler turned up in the area. “I was at Jones Beach, studying gulls, when I got word,” he said. He rushed to his car and tore across Long Island, only to recognize other watchers doing the same. “There was a convoy leading there, and we all knew each other,” he told me. “You could see people with clenched fists on the wheel.” When he arrived at the northern park, a group of birders were already set up with their scopes, like “paparazzi.” Also, there were actual bird photographers, a group of mercenary commercialists Baksh doesn’t much care for. “They want to get the picture, and they’ll do it at all costs,” he said—even “flushing,” or stirring, the prize. Birders who become bird photographers are sometimes said to be “going over to the dark side.”

This is an underlying terror of the pursuit: the fear that all the skill, knowledge, and tech a birder carries will be turned to other ends until, finally, a rare marvel is flushed. It does not take a novelist to see the broader resonance of this concern. Despite their reputation as quirky hobbyists, birders are on the front line of our problematic efforts to defy nature—to travel faster, reach farther, outsmart it—without encroaching on its habits. Their worries are the worries of a nuclear power writ small, and we could do much worse than let them lead us through the forest ahead as they watch the sky.

Correction, Jan. 15, 2011: The article originally stated that a “life list” comprises birds a watcher aspires to see. In fact, it’s generally understood to mean a list of birds seen already. (Return to the corrected sentence.)