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

European hedgehogs face many dangers, especially from cars and garden tools. Their numbers are shrinking, but a new discovery about their hearing could help protect them. Scientists found that these spiny mammals can hear very high-frequency sounds, known as ultrasound.

This finding could lead to new ways to keep hedgehogs safe without bothering people or pets.

A New Hope for Hedgehogs

Hedgehog populations have dropped significantly. Globally, they are considered "near threatened" by the International Union for Conservation of Nature. In the United Kingdom, they are "vulnerable," with populations falling by at least 46% in 13 years. Habitat loss, pesticides, and even household pets also threaten them.

Hope Nothhelfer from the Mammal Society noted that people often say they don't see hedgehogs anymore. This decline led researchers to study the animals' hearing, hoping to find solutions.

CT scans helped scientists create a highly detailed, three-dimensional model of a hedgehog's ear. S. Lund Rasmussen et al, Biology Letters, 2026 under CC-BY-4.0

Scientists studied 20 hedgehogs from Danish rescue centers. They used electrodes to monitor brain activity while playing sounds. They discovered that hedgehogs can hear sounds from 4,000 to 85,000 hertz, with their best hearing around 40,000 hertz. This range includes ultrasound, which is above what humans can hear (20,000 Hz). For comparison, dogs hear up to 45,000 Hz, and cats up to 65,000 Hz.

This means ultrasonic signals could be used to deter hedgehogs from dangerous areas like roads and lawnmowers. These sounds would not affect most pets or people. Sophie Lund Rasmussen, a wildlife ecologist at the University of Oxford, called this discovery a "game-changer" for hedgehog conservation.

How Hedgehog Ears Work

Researchers also used CT scans to create a detailed 3D model of a hedgehog's ear. They found that hedgehogs have small, dense middle ear bones and a partially fused joint between the eardrum and one bone. Their stapes, a small middle ear bone, is light, and their cochlea, the inner ear part for hearing, is short and compact. These features likely help them hear and process ultrasonic sounds very well.

While companies sell ultrasonic pest deterrents, their effectiveness is often questioned. The U.S. Federal Trade Commission has even warned manufacturers about needing scientific proof for their claims.

Scientists are still learning how hedgehogs use ultrasound. They don't know if hedgehogs use it to communicate or find prey. Rasmussen wondered if hedgehogs "blabbering all the time" with sounds humans can't hear.

The next step is to see how hedgehogs react to ultrasound in the wild. The team hopes to work with the automotive industry to design and test sound repellents for cars. Mike Hawes, CEO of the Society of Motor Manufacturers and Traders, supports more research into these tools.

Deep Dive & References

• Hearing and anatomy of the ear of the European hedgehog (Erinaceus europaeus) - Biology Letters, 2026
• European hedgehog listed as Near Threatened on IUCN Red List - Mammal Society, 2024
• Hedgehogs can hear high-frequency ultrasound – that knowledge could help save them - The Conversation, 2025