wasn't that an abomination against humanity?

my vague understanding is that bison were carefully managed by indigenous people pre-1492. like a lot of things Europeans mistook for "natural" because they were unable to grasp the scale of the ecological interventions being made and the sophistication of the agricultural methods. And also by the time the norther parts were assessed by europeans, there was significant ecological disorganization caused by the genocide. And then, the genocide was furthered by intentional destruction of these animals in a strategy to destroy the humans.

eg https://en.wikipedia.org/wiki/Bison_hunting#Native_American_plains_bison_hunting