By Molly Daly

By Molly Daly

PHILADELPHIA (CBS) — The author of a new book will present a special program tonight at the Wagner Free Institute of Science in North Philadelphia.

The program will explore the story of the Passenger Pigeon, a once-numerous species that traveled in flocks so huge they darkened the sun when they passed but they went extinct a century ago.

In “A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction,” Joel Greenberg explores how technology, greed, and human folly wiped out the species.

The birds gathered in flocks numbering in the hundreds of millions, with so many wings beating, they could be heard when they were miles away.

“A minister in New York said that some of their calls,” says Greenberg, “sounded like the sighing of the ancient trees.

The Passenger Pigeon, which Greenberg describes as looked like a Mourning Dove on steroids, was hunted for food and sport.

He says technology turned it into a commodity, “with the expansion of the railroad and the telegraph in the 1840s, it meant that there could be national markets.”

People hoping to cash in chased the huge flocks, creating temporary boom towns.

“You had clerks, and you had the hunters, and you had pluckers, all kinds of people. In fact, one account even mentions harlots,” Greenberg says.

That orgy of consumption wiped out the species.

After 1900, there were no known Passenger Pigeons left in the wild; the few that remained lived in three captive flocks.

The last two survivors, named George and Martha, shared a cage in the Cincinnati Zoo.

“George died in July in 1911, so for three years, Martha was alone, the last of her species,” says Greenberg, “Just decades earlier, here was this abundant bird, reduced to one lone individual that became progressively weaker as the years went on. And finally,” in 1914, “her keeper went to the cage on September 1st, probably about one o’clock in the afternoon, and found her dead.”

“If you end that story on September 1st, it’s a sad story,” says Greenberg. “But the loss of the Passenger Pigeon, the use of heron feathers for hats, the decimation of bison, all of those things became pretty obvious. That spawned the country’s first great environmental movement.”

The first attempt to introduce a federal law regulating the taking of wild birds was made by Congressman John Lacey of Iowa. “He got up in April of 1900 on the floor of the House and said, ‘It is too late for the wild pigeon, but there is still much good to be done.’ ”

The loss of the Passenger Pigeon was an important factor leading to the Lacey Act. “And the next major law was the Migratory Bird Act, approved by the Supreme Court in 1920,” says Greenberg. “And those laws are still the anchors through which this country regulates the taking of its biological heritage.”

Fast forward to the second half of the 20th century, to the passage of the Endangered Species Act. But there’s still resistance to the protections it provides.

“The threats are real, and there is an effort to gut the Endangered Species Act,” says Greenberg, who says he hopes the story of the Passenger Pigeon will alert people to keep vigilant and protect such laws.

The author says the closest analog to what happened to the Passenger Pigeon is what’s going on in the open seas.

“Pelagic fishing,” explains Greenberg, “just can remove all life with these huge nets from the bottom to the surface.” Sharks, and other species, may very well become extinct, and, he says, “it’s for the same reason. There is no sovereign that can prevent the pillaging of the oceans. It’s going to take cooperation.”

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