What was different in the nineteenth century was the sheer pace of the violence. If earlier losses had unfolded gradually—so gradually that not even the participants would have been aware of what was going on—the advent of technologies like the railroad and the repeating rifle turned extinction into a readily observable phenomenon. In the United States, and indeed around the world, it became possible to watch creatures vanish in real time. “For one species to mourn the death of another is a new thing under the sun,” Aldo Leopold noted in an essay commemorating the passenger pigeon’s passing.
