The European hedgehog — one of Britain's most beloved wild mammals — is in trouble. Classified as 'near threatened' by the International Union for Conservation of Nature in 2024, its populations are declining sharply across the UK. And one of the most significant culprits is one of the most mundane: the road.
Up to one in three hedgehogs in local populations is thought to be killed in road traffic accidents. They curl into a defensive ball when threatened — a strategy that works perfectly against foxes and badgers, and catastrophically against cars. For decades, the search has been on for a way to warn hedgehogs away from roads before a vehicle reaches them.
A new discovery from the **University of Oxford** may have just provided the key.
**The Discovery: Hedgehogs Can Hear Ultrasound**
A study published on March 11, 2026 in *Biology Letters* — led by **Assistant Professor Sophie Lund Rasmussen** of Oxford's Wildlife Conservation Research Unit and Department of Biology, in collaboration with the University of Copenhagen — has revealed for the first time that European hedgehogs possess the ability to hear high-frequency **ultrasound**.
Previously, it was entirely unknown whether hedgehogs could perceive sounds in this range. They are not echolocating bats. They are not dolphins. They are small, spiky, ground-dwelling insectivores that most people associate with snuffling quietly through garden borders at night. The discovery that they have a hearing range extending into ultrasound changes the picture entirely.
To be clear: hedgehogs do not use ultrasound the way bats do. But their ears are physically capable of detecting it. And if they can hear it, they can potentially respond to it.
**The Practical Application: Roadside Repellers**
The research team's immediate proposal is to test whether **ultrasonic repellers** — devices already used in various pest deterrent contexts — could be deployed near roads to warn hedgehogs away before they wander into traffic.
The logic is straightforward: if a hedgehog can hear an ultrasonic signal, it can potentially be trained through association, or instinctively deterred, by that signal. A network of low-cost ultrasound emitters positioned along hedgehog-crossing hotspots could create an acoustic warning system that steers the animals away from danger.
Dr. Rasmussen is characteristically careful about the next steps: *"Having discovered that hedgehogs can hear in ultrasound, the next stage will be to find collaborators with whom we can test whether ultrasonic repellers can indeed deter them from roads."* The research team also notes a fascinating open question: are hedgehogs using ultrasound to communicate with each other, or to detect prey? That investigation has already begun.
**A 'Near Threatened' Species**
The discovery matters because the stakes are high. The hedgehog was added to Britain's Red List in 2020, and its near-threatened IUCN status in 2024 formalized what naturalists had been observing with growing alarm for years: populations falling, sightings rarer, the familiar rustle in autumn garden leaves increasingly unusual.
Road mortality is not the only driver — habitat loss, pesticide use, and a decline in suitable foraging ground all play a role. But roads are a direct, lethal, and theoretically preventable cause of hedgehog death. If ultrasound can help, even partially, the discovery of this capability is genuinely significant.
For now, the hedgehog's survival depends on many things: better road design, wildlife-friendly gardening, reduced pesticide use, connected green corridors. But it may also — in time — depend on a little-known fact about its inner ear. The hedgehog can hear the ultrasound. Scientists intend to find out what to do with that. 🦔
*Sources: University of Oxford (ox.ac.uk, March 11, 2026) · Biology Letters (Royal Society Publishing) · University of Copenhagen · IUCN Red List · The Guardian*
