The Last Known Passenger Pigeon Died 100 Year Ago Today -- Here Are 9 Other Animals That Were Hunted To Extinction

The last known passenger pigeon, named Martha, died 100 years ago today at the Cincinnati Zoo. She was 29. The passenger pigeon, which once numbered in the billions in Norther America, has become a symbol of extinction. It was wiped out in the 19th century due to overhunting. Animals face many natural threats, including changing temperatures, predators, and unexpected disasters. But no external stresses have proved more destructive to the survival of other living things than people. The followin...