passenger pigeons

Wikimedia Commons

Later this year, we mark the 100th anniversary of the extinction of the passenger pigeon---the last being a resident of a Cincinatti zoo.  The well-publicized event capped the annihilation of a species whose population at one point was so overwhelming that one ornithologist believed there were more passenger pigeons than all other species combined. 

Efforts to bring the population under control began back in the mid 19th century, in part because enormous flocks wreaked havoc on trees and farms.