Scientists Find Hedgehogs Hear Ultrasound, May Save Species

European hedgehogs are disappearing fast, but scientists just discovered a hidden ability that might help save them.

Researchers at the University of Oxford found that hedgehogs can hear ultrasonic sounds up to 85,000 hertz, far beyond the 20,000 hertz limit of human hearing. Their peak sensitivity sits around 40,000 hertz, well into the ultrasonic range that could make them uniquely responsive to special warning signals.

The discovery came from studying 20 rehabilitated hedgehogs at Danish wildlife rescue centers. Scientists gently monitored their brain activity while the sleeping animals listened to sounds at different frequencies, revealing their remarkable hearing range for the first time.

This matters because hedgehog populations have plummeted by at least 30 percent globally over the past decade. In the United Kingdom alone, numbers dropped 46 percent in just 13 years, leaving only around 500,000 hedgehogs. Cars, lawnmowers, habitat loss, and pesticides threaten these spiny mammals daily.

The team also CT-scanned a hedgehog's ear, creating a detailed 3D model that revealed special adaptations. Small, dense middle ear bones, a compact cochlea, and a partially fused joint between the eardrum and bones help hedgehogs process ultrasonic sounds efficiently.

Now comes the exciting part: ultrasonic devices could warn hedgehogs away from roads and dangerous garden equipment without disturbing humans, dogs, or cats. Since most pets can only hear up to 65,000 hertz, signals above that range would be hedgehog-specific.

The Bright Side

Lead author Sophie Lund Rasmussen calls this discovery a potential game-changer for hedgehog conservation. The automotive industry has already shown interest, with researchers seeking collaborators to design and test ultrasonic car repellents.

Scientists also wonder if hedgehogs might be "blabbering all the time" in frequencies we simply can't hear. When hedgehogs pass each other, clear interactions happen that researchers once attributed only to smell. Ultrasonic communication between hedgehogs could be happening right under our noses, or rather, above our ears.

The next step involves testing whether wild, awake hedgehogs actually respond to ultrasound by moving away from danger. While existing ultrasonic pest deterrents show mixed results, this research specifically identifies hedgehog hearing abilities, making targeted solutions possible.

A simple sound could soon stand between hedgehogs and extinction.