Attempts to save the species by breeding the surviving captive birds were not successful. The passenger pigeon was a colonial and gregarious bird and needed large numbers for optimum breeding conditions. It was not possible to reestablish the species with a few captive birds. The small captive flocks weakened and died.
The last known individual of the passenger pigeon species was "Martha" (named after Martha Washington). She died at the Cincinnati Zoological Garden, and was donated to the Smithsonian Institution, where her body was once mounted in a display case with this notation: