Virginia Rose had just turned 14 when the horse she was riding, in Evergreen, Colorado, spooked and ran under some guide wire, which swept her violently to the ground. “I broke ribs and punctured lungs and all of that,” she says. “But they really think it was the way in which I fell that broke my back, as opposed to the wires.” That was 45 years ago, and she tells the story cheerfully, in a sing-song voice that sounds not unlike the bird chatter surrounding us. It’s a sunny late afternoon on Lake Creek Trail in suburban Austin, where Rose lives, and she has been birding in her wheelchair since 7:30 this morning, as part of a self-imposed challenge to log as many birds as she could from dawn to dusk. The purpose: to raise awareness for Birdability, her new initiative to get mobility-impaired people out in the parks and enjoying nature, by way of birding—and in turn, to make birding more accessible. Birdability is one of the only efforts of its kind in the nation...