The Passenger Pigeon (Ectopistes migratorius) was once probably the most common bird in the world. It is estimated that there were as many as five billion passenger pigeons in the United States. They lived in enormous flocks, the largest probably consisting of 2 billion birds. Such a flock would be a mile wide and 300 miles long, taking several days to pass. During the summer, the passenger pigeon lived throughout the part of Northern America that is east of the Rocky Mountains. In the winter, they lived in the southern US.
The passenger pigeon was a very social bird. It lived in colonies with up to a hundred nests in a single tree, and stretching over hundreds of square miles.
It was hunted for food, and in the mid-1800s it was noticeable that its numbers were dropping. The passenger pigeon only laid one egg at a time, so once numbers started to decline it would have taken time for them to start rising again. Almost all of the remaining quarter million passenger pigeons were killed in a single day in 1896 by sport hunters, who knew they were shooting the last wild flock. Martha, the last known passenger pigeon died in the Cincinnati Zoo on September 1, 1914.
The photograph dates from 1898