"I  seated myself on an eminence, and began to mark with my pencil, making a dot for every flock that passed. In a short time finding the task which I had, undertaken impracticable, as the birds poured in in countless multitudes, I rose, and counting the dots then put down, found that 163 had been made in twenty-one minutes. I traveled on, and still met more the farther I proceeded. The air was literally filled with Pigeons; the light of noon-day was obscured as by an eclipse, the dung fell in spots, not unlike melting flakes of snow; and the continued buzz of wings had a tendency to lull my senses to repose. Before sunset I reached Louisville, distance from Hardensburgh fifty-five miles. The Pigeons were still passing in undiminished numbers, and continued to do so for three days in succession."

This excerpt from an account by naturalist John James Audubon, of a migration of passenger pigeons Ectopistes migratorius in 1813, attests to the extent of their numbers in North America during the 19th century.

A century later they were all gone.

Further on in Audubon's account the reason for the bird's demise becomes clear. While Audubon believed at the time that no amount of slaughter could diminish their number,  the birds were being hunted on a massive scale as food for the poor, the slaves and the pigs. Trees in the pigeons' nesting grounds were felled and burned to bring them down. The birds were intoxicated with alcohol-soaked grain and caught in nets. Hunters tied live pigeons with their eyes sewn closed to stools and, raised high in the air, used them to lure others flying overhead as they flapped their wings in a futile attempt to land. It is from this wicked practice that the name "stool pigeon" is derived.

Laws were passed to try and halt the decrease in numbers which had become evident by the 1870's. In Michigan it was illegal to net birds within two miles of their breeding grounds, but the legislation was not properly enforced; in 1878, in Petoskey, Michigan, 50 000 birds were killed every day for five months, pursued by professional hunters until every last one of the intensely gregarious birds was dead.

By 1897, when barely a bird was to be found in the wild, it was too late to revive the species. The small captive flocks refused to be bred. The species would only initiate courtship and mating when gathered in large numbers.

Martha, the last of the Passenger pigeons, died in Cincinnatti Zoo on September 1, 1914, age 29.