It’s hard to fathom how many passenger pigeons there once were, but writer Joel Greenberg tries to paint a picture in his book, A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction, as reviewed in the current issue of the New Yorker by Jonathan Rosen. Here’s one tasty tidbit:

In 1813, John James Audubon saw a flock–if that is what you call an agglomeration of birds moving at 60 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 260 million rock pigeons [common 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.

There were so many pigeons in the 1800s that they would occasionally break trees and their limbs after settling down upon them, causing feathery avalanches. As late as 1871, one roosting ground in Wisconsin covered 850 square miles (more than twice the land area of New York City), holding more than 100 million birds. In such quantities, hunting birds wasn’t difficult:

Many of the hunting stories have a tall-tale aspect perfectly in tune with the fantastic aura that surrounds the birds. Boys stuck long hickory poles into the ground, pulled on ropes tied to the tips of the poles, and knocked birds down simply by making the poles quiver. Nets were stretched between trees. A roosting ground in Tennessee was set on fire and “scorched corpses were then collected the next day for personal use or sale” from two-foot-high piles of the dead.

But the bounty was misleading. In 1900, a boy in Ohio shot what was then identified as the last wild passenger pigeon with his shotgun. But how did such a widespread animal disappear so quickly?

According to Rosen, the book blames it on the development of railroads and logging after the Civil War. While America was still largely rural, hunting didn’t dent the huge flocks that used to block out the sun. But shortly thereafter, people could find out where flocks were over telegraph wires, travel there to hunt, and sell birds to people in cities, transported by railcar. The invention of refrigerator cars in 1878 didn’t help. Widespread logging also took out many of the forests that the birds depended on for seeds. Furthermore, the birds likely thrived on having such enormous populations, finding safety in numbers. Once these populations plummeted, they lost their competitive advantage.

Interestingly, Americans didn’t at first seem to be able to accept that the birds were gone:

Greenberg hauntingly documents the way people kept “seeing” the birds after the great flocks vanished, or devising outlandish theories to explain where they might have gone. The journal Science speculated that they were in the desert of Arizona; another journal, the Auk, suggested that they were east of Puget Sound, and a lumberman claimed to have seen millions in Chile. Henry Ford was convinced that they had all drowned in the Pacific en route to Asia. The flocks were like phantom limbs that the country kept on feeling. Or perhaps the birds’ disappearance, and the human role in it, was simply too much to bear.

There are now plans to resurrect passenger pigeons using DNA from old specimens, a phenomenon called de-extinction, although it’s unclear if that would be possible or advisable.

The New Yorker