…Birds can be secretive creatures, staying high in the treetops or deep in the underbrush. Even those in plain sight often move startlingly quickly, appearing as hardly more than a flash of color, a blur of wings. Except for the background sound of birdsong, many people are never aware of how many birds — or how few — they share the world with.

Apps like iNaturalist from National Geographic and the California Academy of Sciences help to close that gap, functioning as both electronic field guides and vast data-collection devices. They learn as we learn, improving with every photo and map pin we upload, helping experts understand a planet undergoing profound change. But what of the vast number of birds we never see, those we only hear? To offer that feature — one that accurately and consistently recognizes birds by sound alone — would be the birding equivalent of finding…