This year marks 100 years since the extinction of the passenger pigeon. This uniquely North American bird was estimated to number in the billions at one point in time — only to go extinct in a period of roughly four decades.
The bird was hunted to extinction. Its breeding grounds destroyed.
And the last known passenger pigeon, a female named Martha, died alone in a zoo in Ohio.
I encourage you to visit Project Passenger Pigeon — a year-long effort to raise awareness of this tragedy (and other species tragedies) so that we can work to prevent history from repeating with other species.