Robots mowing grass inadvertently killing eels at night
Stuttgart, Germany - As the number of lawn mowing robots in use increases, concerns about their impact on wildlife, particularly hedgehogs, have risen. These nocturnal animals, when confronted by these automated devices, often roll into protective balls, leading to life-threatening injuries.
A study by the German Federal Environmental Foundation (DBU) and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) last year, alongside hedgehog rescue stations, reported 370 hedgehog victims with cut injuries nationwide from June 2022 to October 2023. Almost half (47%) did not survive. The high number of undiscovered injured or killed animals is a cause for concern, as hedgehogs, if able, retreat into the safety of hedges and bushes following such encounters.
In response, some municipalities such as Cologne, Mainz, and soon Erfurt have implemented night driving bans for lawn mowing robots. Experts propose that restricting operation during night hours, when hedgehogs are most active, significantly reduces the risk of encounters. However, there is no definitive research quantifying the subsequent decrease in hedgehog injuries and deaths directly attributable to these bans.
Nighttime operation of these robots can be profitable for homeowners due to quieter functioning and the ability to be set to mow overnight. In an attempt to protect crepuscular and nocturnal animals, advanced models include cameras, LiDAR, or hybrid sensors to identify and avoid obstacles, including animals. Although sensor technology is improving, current systems may not consistently detect small, close-to-ground creatures like hedgehogs, especially in low light or thick grass.
Manufacturers acknowledge these issues and have done their best to reduce risks. Stihl, for instance, designed its current generation of lawn mowing robots to avoid accidents and offers users the option to program nocturnal operation only if explicitly desired. However, users are cautioned against scheduling nighttime mowing due to potential harm to small animals.
To reduce the overall number of injuries and deaths of hedgehogs, the Federal Environmental Association advises questioning the necessity of a lawn mower robot, suggesting that foregoing its use can benefit not only hedgehogs but insects, amphibians, and other animals as well. Allowing grass to grow tall and flower might contribute positively to biodiversity.
According to the German Wildlife Foundation, hedgehogs have been experiencing a decline in numbers—not solely because of lawn mowing robots. The modern agricultural landscape and well-maintained gardens are lacking suitable habitats for these animals; many hedgehogs are struck by vehicles, and some find it difficult to find food due to the rapid reduction in insects.
The European hedgehog (Erinaceus europaeus) is on the watchlist of the Red List in Germany and classified as "potentially endangered" on the international Red List of the World Conservation Union (IUCN).
- The European hedgehog (Erinaceus europaeus) faces potential endangerment not only due to the impacts of lawn mowing robots, but also because of changes in agricultural landscapes, the lack of suitable habitats, road accidents, and the rapid reduction in insect populations.
- In an effort to preserve the health-and-wellness of hedgehogs and promote environmental-science, the Federal Environmental Association suggests that homeowners question the necessity of using lawn mower robots, as forgoing their use could potentially benefit a variety of animals, including hedgehogs, insects, and amphibians, and contribute positively to biodiversity.
