That is a tougher question than you might think. The original bison on this continent were extirpated by hunters after the Pleistocene. The ones we had when white guys got here originated from Asia, as did the wolf.
The real problem seems to be one of legality. Who paid what when. I read here the rancher did not pay his grazing fees and the enviros did. His cattle are thus grazing on their land.
Indeed, that is a problem. Yet there is another legal problem in that the Feds have no constitutional authority to enforce their contract at gunpoint. That is up to the sheriff.
Now that is an interesting point. We have not learned how this jurisdictional legal nicety was handled.
I don’t know where the authority of Sheriff’s end or where Federal properties are involved. There are US Marshals that might actually have the authority and deputize BLM types for assistance.
I don’t know.