As dusk fell on Chaetura Canyon at the edge of the Texas Hill Country, I joined Paul and Georgean Kyle on the deck of their handcrafted hillside home. Sharp “chippering” calls filled the air while dozens of chimney swifts circled the two 22-foot towers that rose through the eaves five feet above the roof. I saw the swifts separate, one by one, from the swirl of birds and dive into one of the towers. And then I witnessed an amazing touch of visual wizardry. As each bird disappeared into the tower, it immediately reappeared on a big video screen set up before us on the deck, dropping through the dim light in the tower’s interior to squeeze in among the other swifts already clinging to its walls. “They’re beautiful birds in flight,” Paul said as we watched the two spectacles, one in our own world, the other filtered through a small camera the Kyles had fixed inside the tower’s opening. “When you spot a mating pair flying in synchrony, each...