A barn owl’s ability to hunt by hearing alone relies on exquisite variations in the structure of its feathers. A barn owl comes in for a landing. Specialized flight feathers help make its approach nearly silent. / Photo: Phil Robson, via Unsplash A hungry barn owl, unfed for several days, perches in a completely darkened room at Drumlin Farm, a sanctuary run by the Massachusetts Audubon Society. A deer mouse is released into the room, rustling among the two inches of dry leaves that have been placed on the floor. As the mouse pauses, silent, the owl strikes, capturing it. Over the next few days, the owl makes 16 more strikes at mice, missing only four times, each time by less than two inches. To eliminate the possibility that the owl was using its sense of smell or detecting heat from the body of the mouse (for instance, by sensing infrared light emitted by a warm body), the experiment is repeated with a mouse-sized wad of paper dragged through the leaves; the owl again successfully hits its target.…