Robot mowers damage biodiversity and harm many creatures, including hedgehogs, according to German conservationists. Some of them are calling for a ban on nighttime mowing.

Conservationists and scientists in Germany have called for a ban on the nighttime use of robot mowers in order to protect hedgehogs, with a study showing that many of the animals die after being lacerated by the devices.

According to the study from the Leibniz Institute for Zoo and Wildlife Research, almost half of the 370 hedgehogs that were examined after being cut by the mowers’ blades died of their injuries or had to be put down.

Hedgehogs are particularly in danger from mowers operating at night, as the animals are nocturnal feeders and do not flee when in danger, instead relying on their spines as defense — an inadequate protection against the sharp metal blades of a robotic mowing machine.