European Hedgehogs’ Hearing Might Be Attuned to Ultrasonic Sounds. The Discovery Could Help Scientists Save the Declining Species

Sound-based deterrents could help keep the animals away from fast-moving cars and dangerous landscaping equipment

Sarah Kuta | Daily Correspondent

March 20, 2026

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European hedgehogs are in trouble. In an increasingly urbanized world, these spiny mammals often get hit by fast-moving cars—a modern hazard they haven’t evolved to avoid.

But a newly discovered physiological trait might help save the species. European hedgehogs can hear high-frequency ultrasound, scientists report March 11 in the journal Biology Letters, a finding that could lead to sound-based deterrents that don’t disturb people or pets.

In addition to vehicle strikes, hedgehogs are also threatened by habitat loss and fragmentation, pesticides, household pets and garden infrastructure. As of 2024, the International Union for Conservation of Nature considers them “near threatened” globally after documenting population declines of at least 30 percent over the preceding decade.

In the United Kingdom, they were deemed “vulnerable” on the first official Red List for British Mammals, created in 2020 by the nonprofit Mammal Society. At the time, the organization noted that hedgehog populations in the nation had dropped by at least 46 percent over the previous 13 years, for a total population of around 500,000.

“When hedgehogs come up in conversation, it’s not long before someone says that they just don’t see them anymore,” Hope Nothhelfer, editorial lead for the Mammal Society, said in a 2024 statement.

With this decline in mind, researchers wondered if having a better understanding of the animals’ hearing abilities might inspire some conservation solutions.

They anesthetized 20 rehabilitated hedgehogs from Danish wildlife rescue centers, then placed small electrode needles just under the skin on their skulls. Then, they exposed the sleeping animals to sounds of various frequencies—which correspond to pitch—while monitoring their brain activity.

Hedgehogs can hear sounds ranging from 4,000 to 85,000 hertz, with peak sensitivity around 40,000 hertz, the team found. This means their hearing extends well into the ultrasonic range, which are sounds above 20,000 Hz—a threshold at the upper limit of human hearing. Meanwhile, dogs can detect frequencies from 67 to 45,000 Hz, and cats can hear from 45 to 65,000 Hz.

The discovery suggests that ultrasonic signals outside of common pets’ hearing range could be used to keep hedgehogs away from roads and other dangerous equipment, like lawnmowers.

“This could be a game-changer for hedgehog conservation,” writes lead author Sophie Lund Rasmussen, a wildlife ecologist at the University of Oxford in England, for the Conversation.

The scientists also CT-scanned the ear of a deceased hedgehog, which allowed them to create a detailed, three-dimensional model that revealed some previously unknown features.

Hedgehogs have small, dense middle ear bones, plus a partially fused joint between the eardrum and one of the bones. They also have a small, light middle ear bone called the stapes, plus a relatively short and compact cochlea, the spiral-shaped cavity in the inner ear that supports hearing. Together, these adaptations seem to help hedgehogs transmit and process ultrasonic sounds efficiently and effectively, according to the researchers.

For now, scientists don’t know whether or how hedgehogs use ultrasound to communicate with each other or detect prey.

“When hedgehogs pass by each other, you can tell that they are interacting,” Rasmussen tells BBC News’ Georgina Rannard. “Maybe that’s just chemical reactions to smelling each other. But imagine that they’re actually blabbering all the time, and we just couldn’t hear it.”

They also don’t know how the animals respond to ultrasound while they’re awake and in the wild, so it’s an open question as to whether ultrasonic signals would make effective hedgehog deterrents. The team wants to find automotive industry collaborators who could help design and test hedgehog sound repellents for cars.

Mike Hawes, CEO of the Society of Motor Manufacturers and Traders, a trade association for the U.K. automotive industry, tells BBC News he would like to see “more detailed research” to understand the potential effectiveness of such tools.

Sarah Kuta | Read More

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.