Gary Nabhan and I are bumping along in a rental car down a two-track dirt road that follows the edge of Sonoita Creek’s floodplain, some 29 kilometers north of the Arizona–Mexico border. Nabhan—an ethnobiologist, conservation biologist and agroecologist at the University of Arizona and author of more than 30 books on food, farming and nature—tells me how extraordinary this borderlands region is for pollinators: native bees, butterflies, hummingbirds, even nectar-feeding bats. And now he is…