Bats zipping around at dusk know where they’re going, despite flying in near darkness; they detect their ultrasound calls bouncing off objects and use these echoes to find their way around. But which of these numerous echoes do bats rely on for orientation?

Experiments have shown that bats can learn to rely on a single echo-reflecting object to figure out where to go — and that if that acoustic landmark is moved then it can really confuse them.