Cruel: Passenger Pigeon
There was a time when Passenger Pigeons were so abundant that flocks would take hours — HOURS — to pass by. They were so loud you could not have a conversation and their immense numbers would block out the sun. Humans mistakenly thought a creature with such abundance could never be affected, and cruelly hunted them into extinction. The very last Passenger Pigeon died in 1914. The upside: this tragedy helped give birth to a new era of modern conservation.