Grizzly 399 and her first set of triplets. Nature tourism is a multi-billion dollar industry in Greater Yellowstone and the Northern Rockies and one of the biggest drivers is wildlife watching. Two of the top attractions are grizzly bears and wolves in Yellowstone and Grand Teton. However, those two national parks are not large enough, by themselves, to sustain wildlife that migrates and has large home ranges. The health of public wildlife depends on the ecological health of private lands surrounding public lands. "Teton Rush Hour" photo courtesy Thomas Mangelsen. To see more of his collectible photography go to mangelsen.com