Claudio Mello was conducting research in Brazil’s Atlantic Forest about 20 years ago when he heard a curious sound. It was high-pitched and reedy, like a pin scratching metal. A cricket? A tree frog?

Did you happen to hear a strange chirping sound at some point today, causing you to look around the room, perplexed, convinced that a small bird had somehow entered your home? Did you look it up ...

I was recently creeping through a clearing of downed trees in a wooded Brooklyn park with my iPhone in hand. Birds were singing everywhere, but through the din, I was recording a peculiar song: It was ...