Hedgehogs Hear Ultrasound Up to 85 kHz, Opening Door to Targeted Repellents

Hedgehogs detect sounds up to 85 kHz, far beyond human hearing. Researchers recorded brain responses in anaesthetised hedgehogs and found they respond to frequencies well into the ultrasonic range, surpassing the 20 kHz limit for humans and exceeding dogs (45 kHz) and cats (65 kHz) [1].

The study used pulse‑beep soundtracks and brain‑wave monitoring. Working with bio‑acousticians, the team played a custom soundtrack to rescued hedgehogs and measured neural activity to pinpoint audible frequencies [1].

A stiff chain of ear bones lets high‑pitched sounds pass efficiently. 3‑D modelling revealed a rigid ossicular chain that channels ultrasonic vibrations, a mechanism similar to that of echolocating bats [1].

Findings could enable ultrasonic devices to keep hedgehogs away from hazards. Researchers aim to develop sound repellents for cars, lawn‑mowers and strimmers; the Society of Motor Manufacturers and Traders notes ultrasonic whistles are already sold to consumers [1].

Hedgehogs are near‑threatened, with thousands killed in road collisions each year. The species’ decline across the UK and Europe makes mitigating stressors in rescue centres and on roads a conservation priority [1].

Further work will identify the most effective deterrent tones and avoid garden avoidance. Both the scientists and SMMT’s chief executive stress that additional testing is needed to confirm efficacy and ensure hedgehogs are not driven from essential garden habitats [1].