A bruiser of a thunderstorm roared through my neighborhood recently, tearing down countless tree branches and even some hefty limbs. Along with the mushrooms that sprouted after the soaking rain, the storm’s aftermath brought another sort of emergence: Dozens of brown paper yard waste bags, stuffed with debris, popped up along the curbs. Being cheap and slothful, I didn’t join my neighbors in buying bags, stuffing them with sticks, and paying my city government to come pick them up. (Not that there’s anything wrong with that.) Instead, I spent a few minutes gathering downed branches and twigs and threw them on my brush pile. Free, easy—sold. There’s also a more virtuous reason to build a brush pile: It’s a supremely simple and effective way to make your neighborhood more welcoming to birds. “What these things become are little shelter spots for all sorts of wildlife,” says David Mizejewski, a naturalist with the National Wildlife Federation. “They become...