It started in 2002: The bears around Durango, Colorado, came down from the hills to feast on the city’s garbage. Normally, natural food—nuts and berries and acorns—keeps them in the woods, but a series of droughts and late freezes in 2002, 2007, 2012 and 2017 left them hungry. Despite their fear of...

My husband and I were contemplating whether to hike the 3-mile trail in Utah’s Zion National Park that September day. I’d read that this trail was our best chance to spot bighorn sheep, but after a week of exploring the five national parks in the state, our bodies were tired—and it was already late...