Instant Genius How ultrasound tech could save hedgehogs
May 10, 2026
Dr Sophie Lund Rasmussen, aka Dr Hedgehog, is a hedgehog researcher at Oxford and Copenhagen. She describes hedgehog declines, what makes them fascinating, and how to make gardens hedgehog friendly. She explains measuring hedgehog hearing, finding peak sensitivity near 40 kHz, and explores using ultrasound repellers to reduce road collisions and improve safety.
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Childhood Hedgehog Encounter Sparked A Career
- Sophie Lund Rasmussen first became fascinated by hedgehogs after hearing a terrifying mating scream in her garden as a child.
- She discovered two hedgehogs mating, lay down to watch them freeze in the torchlight, and that memory launched her lifelong research.
Roads Are The Main Cause Of Hedgehog Decline
- Road traffic is the single biggest driver of European hedgehog decline, with about one in three hedgehogs killed on roads each year.
- UK rural populations may have fallen by ~75% since 2000, so reducing road mortality by even 10–15% would substantially aid conservation.
Make Your Garden A Hedgehog Highway
- Make gardens hedgehog friendly by providing entrances and natural nesting material like leaf piles and cut branches.
- Create small holes in fences to form hedgehog highways so animals can travel between gardens without crossing roads.