Fermilab has had a herd on the grounds since the beginning. Used to be that visitors could get pretty close (but still behind the fence), but I haven't visited in many years.
While of course the bison there are fine, this reminds me of the National Lampoon's joke newspaper from Dacron, Ohio. One running joke there was an effort by environmentalists to protect the Dacron Nine-eyed Trout, which was only found near Dacron's nuclear power plant.
My uncle worked at Fermilab. The joke there was that the bison were the ultimate problem detectors. "If we look out at the ring and the bison are all dead, then we really have a problem".