Although not quantified, there are growing concerns that an increasing number of hedgehog injury cases may have been caused by robotic lawn mowers. Robotic mowers are becoming increasingly popular and often run at night when hedgehogs are active. Already in serious decline for a myriad of reasons (habitat loss, road traffic accidents, intensive agriculture, injuries from dog bites and garden strimmers), concerning reports from hedgehog rehabilitation centres indicate a significant increase in the numbers of hedgehog injuries caused by robotic lawnmowers.
Lead researcher at the University of Oxford, Dr Sophie Lund Rasmussen said: “There is an urgent need to identify and phase out models of robotic lawnmowers that pose a threat to hedgehogs. Our new standardised safety test will greatly aid hedgehog conservation, by enabling manufacturers of robotic lawnmowers to ensure their models are “hedgehog friendly” before they are put on the market”.
According to Dr. Rasmussen, all the tested robotic lawn mowers physically touch the hedgehog in order to detect it, though some failed to do so all together. In mild cases, the robotic mower would lightly nudge the hedgehog then change direction, but in the worst-case scenario, the machine ran straight over it with the blades still running, causing extensive damage. The research initially used dead hedgehogs (collected from rehabilitation centres) but now use a specially designed hedgehog ‘crash test dummy’ to ascertain the mowers capability to detect and/or cause damage in a collision.
Extended research at a hedgehog rehabilitation centre in Denmark to establish how live hedgehogs, react to robotic mowers, showed three distinct reactions: running away from the mower; standing rigidly in front of it partially curled up; or sniffing the lawnmower inquisitively. Generally, younger hedgehogs were more bold than adult hedgehogs and hence possibly more at risk.
Ultimately, the researchers hopes that the hedgehog safety test using the dummies will become integrated into the official testing protocols approving the robotic lawnmowers for sale on the European market. Furthermore, a possible phasing out of robotic lawnmowers that pose a threat to hedgehogs.
Current owners (and vendors) of robotic lawnmowers are advised to check for any hedgehogs on the lawn before mowing and only running the machines during daylight hours, since hedgehogs are predominantly nocturnal.
The published research papers:
- ‘Wildlife Conservation at a Garden Level: The Effect of Robotic Lawn Mowers on European Hedgehogs‘ (Erinaceus europaeus), by Sophie Lund Rasmussen, Ane Elise Schrøder, Ronja Mathiesen,Jeppe Lund Nielsen, Cino Pertoldi and David W. Macdonald, MDPI, 21 April 2021.
- ‘Facing Danger: Exploring Personality and Reactions of European Hedgehogs (Erinaceus europaeus) towards Robotic Lawn Mowers‘, by Sophie Lund Rasmussen, Bettina Thuland Schrøder, Anne Berger, Rahel Sollmann, David W. Macdonald, Cino Pertoldi and Aage Kristian Olsen Alstrup, MDPI, 29 December 2023.