One hundred years ago in September, Martha the passenger pigeon died in a Cincinnati zoo.
She was the last of a North American species whose population once had numbered in the billions. Naturalist John James Audubon once described a mile-wide migratory flock that darkened the Kentucky skies for days in 1813 -- and brought the Louisville population to the banks of the Ohio River with their guns.
Even discounting for artistic license, that’s a lot of birds.
The extinction of Ectopistes migratorius, punctuated by Martha’s demise, has become a lesson taught in generations of ecology courses about what happens when humans over-hunt animals and destroy their...