A mother elk and her calf, among thousands of adult wapiti that migrate into Yellowstone National Park from every direction in late spring and then give birth to young. Elk are vulnerable to disturbance, not only form development impacting habitat but studies show how recreation pressure on trails can displace elk from places where they want to be. That's why Wilderness areas, where typically there is less of a hubbub of human activity, are important places where elk can have habitat security. Photo courtesy Jacob W. Frank/NPS