Hedgehogs have super-hearing that could prevent them from being hit by cars – if manufacturers adapt their vehicle designs – a new study has suggested.
One in three hedgehogs is killed in road traffic incidents, as the population faces a grave decline, according to the International Union for Conservation of Nature in 2024.
But a new study by the University of Oxford has discovered that the much-loved mammal can hear high-frequency ultrasounds, with their hearing sharper than that of dogs or cats.
The researchers found that ultrasound repellers could be used to deter hedgehogs from roads, reducing the number killed by cars.
Dr Sophie Lund Rasmussen, assistant professor at Oxford’s wildlife conservation research unit, said: “Having discovered that hedgehogs can hear in ultrasound, the next stage will be to find collaborators within the car industry to fund and design sound repellents for cars.
“If our future research shows that it proves possible to design an effective device to keep hedgehogs away from cars, this could have a significant impact in reducing the threat of road traffic to the declining European hedgehog.”
In the study, researchers collaborated with colleagues in Denmark to test the auditory brainstem response of 20 rehabilitated hedgehogs from Danish wildlife rescue centres.
This method uses small electrodes placed on the animals to record electrical signals travelling between the inner ear and the brain, while short bursts of sounds are played through a small loudspeaker.
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The electrodes detected that the brainstem fired when signals were played across a range of 4-85kHz, with a peak sensitivity around 40kHz. This demonstrates that hedgehogs can hear in the ultrasound range (which starts at frequencies greater than 20kHz), up to at least 85kHz.
After being checked by a veterinarian after the experiments, the hedgehogs were released back into the wild the following night.
Professor David Macdonald, co-author of the study, said: “It is especially exciting when research motivated by conservation leads to a fundamental new discovery about a species biology which, full circle, in turn offers a new avenue for conservation.
“The critical question now is whether the hedgehogs respond to ultrasound in ways that might reduce the risks of collisions with robotic lawnmowers or even cars.”
The study ‘Hearing and anatomy of the ear of the European hedgehog Erinaceus europaeus’ has been published in Biology Letters.
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