Research indicates that robotic lawnmowers kill hedgehogs because they cannot see them despite sometimes being able to see other objects. Scientists, in a study, evaluated 18 models of robotic lawnmower in collision tests using dead hedgehogs. The dead hedgehogs had been taken to rehabilitation centres in Denmark and had not survived.
The mowers were pointed towards the hedgehogs on a flat, well-trimmed lawn. They did the same test against juvenile and adult hedgehogs. Even those mowers that had cameras able to detect obstacles and avoid them failed to detect the hedgehogs and bumped into them.
The robotic lawnmowers that pose the greatest risk are those that were more powerful and had rear wheel drive together with fixed blades as opposed to pivoting blades with foldaway when encountering an obstacle. Also, mowers with skid plates which protect the blades caused less damage to the animals.
Robotic mowers are causing more damage to hedgehogs because there has been a 12% growth in sales year-on-year with the value of global sales hitting £1 billion.
The lead author of the study is Dr. Sophie Lund Rasmussen at the University of Oxford and Aalborf University in Denmark. The researchers are going to build hedgehog crash test dummies in order to help develop a lawnmower that is safer for them. Rasmussen is presenting the results and insights to the manufacturers and they want a collaboration with them to develop wildlife-friendly robotic lawn mowers.
The chief executive of the British Hedgehog Preservation Society which funded the study said that they are hopeful that they can offer advice to industry protect hedgehogs against these machines. They advise owners of the mowers not to use them at night when they are more likely to encounter hedgehogs.