The Passenger Pigeon was the most abundant bird in the world during the time of the Civil War.
When rations were lean, soldiers from both armies could often count on a meal if they were a good shot, as one out of every four birds in North America was a passenger pigeon.
The bird was considered an easy target, and before the advent "clay pigeons", these individuals were being sold and used as the real thing.
If a flock were to fly over, which happened often in those days, one merely had to aim his weapon to the sky and fire their weapon once, often hitting two or more birds with the shot.
A single flock of 3.5 BILLION birds flying over might darken the sky and take more than 14 hours to pass, as was recorded in Ontario in 1866.
http://en.wikipedia.org/wiki/Passenger_pigeon
Indigenous people killed and ate the birds too, but as they were more far sighted than white people, they knew to only steal the young from the nests and left the adults to reproduce.
The white man however, being the capitalistic savage that he is, slaughtered the birds on a massive scale throughout the 19th century, and sold its meat to the market.
Meanwhile shopping plaza's and project development impeded its nesting grounds and habitat.
The last passenger pigeon, "Martha", named after George Washington's old lady, died in the Cincinnati Zoo in 1914.
If you want to see a real passenger pigeon- I think they may have her stuffed away in a box somewhere at the Smithsonian.