In 1809, John James Audubon made this pastel and ink sketch of a passenger pigeon in Ohio. The last great massacre of the birds took place in Petoskey, Mich., in 1878. (Special Collections Research Center, University of Chicago Library/Library of Congress)

Slaughtered to extinction: Passenger pigeons in Michigan

September 1, 2014 marked the hundredth anniversary of the death of the passenger pigeon Martha, the last known living member of her species.