"What is all that greedy looking that birdwatching induces, a kind of gobbling need to know and see and marvel, but a hunger for life?" asks Jonathan Rosen in The Life of the Skies: Birding at the End of Nature (Farrar, Straus and Giroux). This lightly literary meditation on nature and civilization—both endangered these days—makes an eloquent case for raising our sights to creatures as fragile and transcendent as our own humanity.