Hedgehogs hear ultrasound

Recently published research from the University of Oxford finds that hedgehogs can hear high frequency ultrasound.  Across Europe hedgehog populations are shrinking, and the European hedgehog is listed as "near threatened" on the International Union for Conversation of Nature red list for Europe. The researchers believe it could be possible to design sound-based deterrents that target hedgehogs specifically, without disturbing people or their pets. In theory, ultrasonic signals could warn hedgehogs away from approaching vehicles or keep them clear of dangerous machines in the future. This is significant because one of the greatest threats to hedgehogs is cars, with some studies suggesting up to one in three hedgehogs may die on roads in Europe every year. Their primary defence strategy evolved to escape natural predators that see movement in the dark. They freeze, assess the threat, and then either flee or curl into a tight ball of spines - this defensive behaviour makes them defenceless when faced by a car. Roads and fences also fragment landscapes, making it harder for hedgehogs to find food, mates and new habitats.