Around 200 years ago, the passenger pigeon (Ectopistes migratorius) was the world’s most abundant bird. Although the species was found only in eastern North America, it had a population of between three and five billion (25 percent of the North American land bird population). Overhunting caused a chain of events that reduced their numbers below minimum threshold, causing them to go extinct. In the 1890s, several states passed laws to protect the pigeon, but it was too late. The last known wild bird was shot in 1900; the last passenger pigeon in captivity, named Martha, died on September 1, 1914, in the Cincinnati Zoo.