Oxford study finds hedgehogs hear ultrasound up to 85 kHz: full analysis

A new Oxford-led study suggests European hedgehogs may hear far more of the soundscape than clinicians, rehabilitators, and conservation planners realized. Researchers found that the species can detect frequencies from 4 to at least 85 kHz, placing part of its hearing squarely in the ultrasonic range and raising the possibility that ultrasound-based deterrents could one day help keep hedgehogs away from cars and other dangerous equipment. (ox.ac.uk)

The idea matters because road traffic has long been recognized as a serious threat to hedgehogs, alongside the broader effects of habitat fragmentation. Prior conservation work has linked roads not only to direct mortality, but also to isolation of local populations, which can increase the risk of local disappearance. That context helps explain why researchers are interested in tools that could prevent collisions before they happen, rather than relying only on habitat mitigation after roads are built. (hedgehogstreet.org)

In the new study, investigators tested 20 live hedgehogs from Danish wildlife rescue centers using auditory brainstem response, a method that records neural activity between the ear and brain while sounds are played. They found peak sensitivity around 40 kHz and responses across 4 to 85 kHz. The team also used high-resolution micro-CT scans to reconstruct hedgehog ear anatomy, identifying small, dense middle-ear bones and a partly fused ossicular joint that may stiffen the auditory chain and improve transmission of high-frequency sound. Oxford said the animals were examined by a veterinarian after testing and released the following night. (ox.ac.uk)

The translational angle is what pushed the paper beyond a pure comparative-auditory finding. Oxford researchers said the work could support design of ultrasound repellents for cars, and potentially for lawnmowers and hedge trimmers as well. But the concept is still early. As outside coverage noted, researchers do not yet know whether hedgehogs use ultrasound naturally for communication or prey detection, or whether free-ranging hedgehogs would reliably avoid an ultrasonic signal in the field. (ox.ac.uk)

There has been some cautious industry interest, rather than immediate endorsement. Smithsonian’s reporting, citing BBC News, noted that Mike Hawes of the U.K. Society of Motor Manufacturers and Traders said he would want more detailed research before judging the effectiveness of such tools. That response fits the current evidence base: the study establishes hearing capacity and anatomical plausibility, but not yet a validated roadside intervention. (smithsonianmag.com)

Why it matters: For veterinary professionals, this is a reminder that sensory biology can have direct welfare implications. Wildlife veterinarians and rehabilitators may need to think more carefully about acoustic environments during treatment and recovery if hedgehogs are sensitive to frequencies outside the human hearing range. Longer term, if deterrent systems are shown to work, they could become a prevention tool that complements rehabilitation by reducing trauma cases at the source. For clinicians who also advise pet parents keeping hedgehogs where legal, the study may eventually shape recommendations around household devices marketed as ultrasonic. (ox.ac.uk)

What to watch: The key next milestones are behavioral trials in awake hedgehogs, field testing near roads or garden machinery, and any partnerships with automotive or device manufacturers. Until those data arrive, the most defensible takeaway is that hedgehogs can hear ultrasound, not that ultrasound deterrents are ready for clinical or conservation deployment. (ox.ac.uk)