Every night in the summer, more than 15 million bats emerge from a hot, cavernous sinkhole just outside San Antonio. They spiral up and out of the cave’s gaping mouth like a tornado and slowly gain elevation. If you’re sitting nearby, you can feel the wind from their wings.

Once the bats reach the treetops, they form columns that flow out and over the hills like plumes of smoke that appear to never end. It’s dinner time in Texas, and in the corn and cotton fields, the hairy, winged mammals will feast on moths throughout the night.