In his new book about the passenger pigeon, the naturalist Joel Greenberg sets out to answer a puzzling question: How could the bird go from a population of billions to zero in less than fifty years? Painting by Walton Ford / Photograph by Butcher Walsh

Imagine that tomorrow morning you woke up and discovered that the familiar rock pigeon—scientifically known as Columba livia, popularly known as the rat with wings—had disappeared. It was gone not simply from your window ledge but from Piazza San Marco, Trafalgar Square, the Gateway of India arch, and every park, sidewalk, telephone wire, and rooftop in between. Would you grieve for the loss of a familiar creature, or rip out the spikes on your air-conditioner and celebrate? Perhaps your reaction would depend on the cause of the extinction. If the birds had been carried off in a mass avian rapture, or a pigeon-specific flu, you might let them pass without guilt, but if they had been hunted to death by humans you might feel honor-bound to genetically engineer them back to life.

This thought experiment occurred to me while reading “A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction” (Bloomsbury), Joel Greenberg’s study of a bird that really did vanish after near-ubiquity, and that really is the subject of Frankenpigeon dreams of resurrection. Even before the age of bioengineering, Ectopistes migratorius could seem as much science-fiction fable as fact, which is why it is good to have Greenberg’s book, the first major work in sixty years about the most famous extinct species since the dodo.

The passenger pigeon—sometimes called “the blue pigeon,” for its color, though the blue was blended with gray, red, copper, and brown—should not be confused with its distant cousin, the message-bearing carrier pigeon, which is really just a domesticated rock pigeon in military dress. Unlike the rock pigeon—domesticated six thousand years ago, now feral, and brought to these shores by Europeans in the early seventeenth century—the passenger pigeon was native to North America, where it roved over a billion acres of the continent searching for bumper crops of tree nuts. It was here, like the American bison, when Europeans arrived, and it was here when the peoples we consider indigenous migrated across their land bridge thousands of years before that. It evolved on the unspoiled continent and was allied with the big trees that once covered much of the Northeast and the Midwest.

The passenger pigeon was also the most numerous bird species in North America, and possibly the world, dominating the eastern half of the continent in numbers that stagger the imagination. In 1813, John James Audubon saw a flock—if that is what you call an agglomeration of birds moving at sixty miles an hour and obliterating the noonday sun—that was merely the advance guard of a multitude that took three days to pass. Alexander Wilson, the other great bird observer of the time, reckoned that a flock he saw contained 2,230,272,000 individuals. To get your head around just how many passenger pigeons that would mean, consider that there are only about two hundred and sixty million rock pigeons in the world today. You would have to imagine more than eight times the total world population of rock pigeons, all flying at the same time in a connected mass.

No wonder witnesses frequently described the birds in quasi-Biblical, if not apocalyptic, language. A flight over Columbus, Ohio, in 1855 elicited the following eye-witness account:

As the watchers stared, the hum increased to a mighty throbbing. Now everyone was out of the houses and stores, looking apprehensively at the growing cloud, which was blotting out the rays of the sun. Children screamed and ran for home. Women gathered their long skirts and hurried for the shelter of stores. Horses bolted. A few people mumbled frightened words about the approach of the millennium, and several dropped on their knees and prayed.

On the ground, the birds were equally prodigious. A joint at the corners of the lower bill enabled their mouths to more than double in size. Their crops could hold “up to a quarter of a pint of foodstuffs,” and they could vomit at will if they saw a food that they liked better. Thoreau, a keen watcher of the birds, marvelled that they could swallow acorns whole. A Detroit newspaper in the late nineteenth century described the squabs as having “the digestive capacity of half a dozen 14-year-old boys.”

In their wake, passenger pigeons left behind denuded fields and ravaged woods; descriptions conjure up those First World War photographs of amputated trees in no man’s land. “They would roost in one place until they broke all the limbs off the trees,” one old-timer recalled, “then they would move to Joining timber & treat it likewise, then fire would break out in the old Roost and Destroy the remainder of the timber.” Their droppings, which coated branches and lay a foot thick on the ground, like snow, proved toxic to the understory and fatal to the trees.

One hunter recalled a nighttime visit to a swamp in Ohio in 1845, when he was sixteen; he mistook for haystacks what were in fact alder and willow trees, bowed to the ground under gigantic pyramids of birds many bodies deep. As late as 1871, a single nesting ground in Sparta, Wisconsin, covered eight hundred and fifty square miles, hosting more than a hundred million birds.

But the profusion was misleading. Twenty-nine years later, a boy in Ohio shot a passenger pigeon out of a tree with a twelve-gauge shotgun, killing what was quickly identified as the last wild member of the species (though Greenberg has discovered evidence of a specimen taken in 1902). A small captive population remained at the Cincinnati Zoo, including a pair patriotically named George and Martha, but there would be no new feathered nation. By 1910, Martha was the sole survivor, an extraordinary fate for a bird whose ancestors had, in Audubon’s words, sounded—from a distance!—like “a hard gale at sea, passing through the rigging of a close-reefed vessel.”

Martha spent four years as a melancholy zoo attraction. Visitors tossed sand to get her to move. Officials offered a thousand-dollar reward for a mate, but on September 1, 1914, the last passenger pigeon in the world died.

That we know the date is part of the jarring incongruity of the story. Imagine knowing that the last Tyrannosaurus rex keeled over on a Tuesday in June. Newspapers described how Martha was frozen in a three-hundred-pound block of ice and sent by train from Cincinnati to Washington, D.C. There she was skinned, stuffed, and put on display at the Smithsonian for a nation guiltily waking up to its role in the destruction of the bird and its habitat.