I don't know the details of this questionable action by the feds. Since the land doesn't seem to be for public use, the 5th Amendment wouldn't apply. So the only constitutional justification that might apply is the Constitution's Clause 17 of Section 8 of Article I where the feds buy state land with the consent of a state's legislature.
But even if the feds purchased the land under Clause 17, it remains that the states have never delegated to Congress, via the Constitution, the specific power to define and protect endangered species.
So what am I overlooking?
Again, I don't know the detail of this issue.
Ranchers herd cattle; sheep herders ... ; oil and gas production; timber and mining; ski and other recreational areas for hiking, mtn biking, horses, 4x4 roads to historical cabin inholdings; Spanish land grants before there was a Mexico ... ;
Former lands of Many Uses , and ...
Public lands are often leased .
This is another clever way by the eco- terrorists to vacate legal and long term allotments.