The Colorado law does not distinguish by species. It applies to OWNED livestock. If the rancher OWNED the buffalo, then that is the end of the story. If the jury considers those buffalo as OWNED LIVESTOCK, then they are not wild and the law applies to them. Likewise, the dude is required to build a fence CAPABLE OF KEEPING THEM OUT. The buffalo were there before he was. Park County regulations make that clear.
The 3 wire fence is mentioned merely as a MINIMUM. If more is needed then he should build an adequate fence capable of holding them out. Three strands of barbed wire and 20 feet between posts is sure a MINIMUM FENCE. Any rancher will tell you that you dont space fence posts more than a rod apart (16.5 feet), and most fences where buffalo are held are at least 5 wires with wood posts every rod and steel posts half way in between. The dude will not win because the local people will not allow that sort of precedent to happen.
> The dude will not win because the local people will not allow that sort of precedent to happen.<
I think you answered the true reason right there.