This certainly isn’t interstate commerce. Where does the US Constitution give the federal government the power to declare protected species? Could someone please point that out, because I’m not seeing it.
BTW, I have no problem with state laws protecting species. I don’t even oppose the federal government acting in an advisory capacity on endangered species. They could even help the states reach mutual agreements to protect certain species like wolves, but I don’t see how they can legally (constitutionally) make it a federal crime for someone to kill a wolf.
Treaty law underlies every major environmental statute.