October 1, 2021, 1:18 pm | Read time: 6 minutes
Robotic lawn mowers promise a well-kept lawn with minimal maintenance. But this convenience comes at a cost—not just financially. The mowers pose a threat to small animals in the garden, such as hedgehogs, which are particularly active in the evening and at night. myHOMEBOOK reached out to animal welfare advocates and manufacturers to find out how significant the danger really is and what robotic mower owners should be aware of.
Small animals are easily overlooked among tall blades of grass. Robotic mowers often detect hedgehogs too late with their sensors, causing their blades to harm the animals. But it’s not just hedgehogs that are affected; toads and lizards are also at risk.
Why are robotic mowers so dangerous for hedgehogs?
While the sensor technology of robotic mower manufacturers is gradually becoming more sophisticated, animal welfare advocates are increasingly sounding the alarm. “The robots are very quiet and have little deterrent potential,” explains Sebastian Kolberg from NABU in response to a query from myHOMEBOOK. “Moreover, there is no uniform standardization regarding the design, such as how far the blade must be from the outer shell,” says the wildlife conservation officer.
Many robotic mower owners turn on the devices in the evening when they are at home. However, hedgehogs are particularly active at dusk and night. “If robotic mowers run at night or at dusk, nocturnal hedgehogs are especially at risk,” warns the Nature Conservation Association of Baden-Württemberg. “The mowers do not stop for playing children, whose fingers can get caught under the blades, nor for small animals.”
Related: Found a hedgehog in the garden? How to act correctly
Unlike other garden animals, hedgehogs do not run away to seek shelter when in danger—they stay put and curl up, as reported by the Bavarian Society for the Protection of Birds (LBV). While this learned behavior may deter predators, robotic mowers are unfazed. The result is severe injuries, as the animals are run over and harmed. In many cases, injured hedgehogs end up in animal shelters, where caretakers nurse them back to health. In the worst case, they die painfully on the spot. “They are run over, mutilated, and killed,” warns NABU Lower Saxony.
Robotic mowers rob hedgehogs of their habitat
Robotic mowers also pose an indirect threat to hedgehogs by depriving them of their food source. When the grass is cut short, the spiny animals cannot find enough food for hibernation and must travel further to search. The LBV therefore recommends that “garden owners should focus on biodiversity and forgo the electric helpers.”
How advanced is the technology in robotic mowers?
The sensors of robotic mowers are often still unable to detect and avoid obstacles. Small hedgehogs, in particular, quickly fall victim to the sharp and fast-rotating blades, “simply because of their body size,” says Kolberg. When Stiftung Warentest examined eight different robotic mowers from manufacturers like Bosch, Husqvarna, and Gardena in 2018, the test results were devastating. None of the tested models could impress and achieve a better rating than “satisfactory.”
The mowing performance was not the decisive criterion for the poor results, but rather the safety aspects. An accident risk was identified with all robotic mowers, especially for playing toddlers. Two mowers failed the test outright because they did not stop when a child’s shoe was in the way.
What do robotic mower manufacturers say about this?
Manfred Eckermeier, press spokesperson for Positec, is well aware of the safety risks of robotic mowers. The company includes the Worx Landroid in its product range. “We recommend that all users of robotic mowers handle such devices with caution,” Eckermeier says in response to a query from myHOMEBOOK. “As with all machines that work with cutting tools.”
He strongly advises robotic mower owners: “Children or animals should never be left unattended when a robotic mower is operating,” the company spokesperson advises. Additionally: “Never let the robotic mower run at night when hedgehogs and other wildlife are foraging.”
Indeed, it can sometimes happen that the sensors do not detect a flat obstacle on the ground. Eckermeier cites various factors such as “lawn conditions, possible holes in the lawn, or elevations.” The anti-collision system is also not a hundred percent guarantee in light of these factors. It is designed to detect and avoid obstacles at a height of 15 centimeters and a minimum distance of 25 centimeters. “We are constantly working on the safety systems of our devices and continuously developing them,” assures the spokesperson.
According to George Brown from the Garden Industry Association (IVG) e.V., collisions are “tragic individual cases,” but he also appeals to the device owners. A robotic mower is “a powerful machine and not a toy,” says the technical officer. “International product standards therefore require high safety features, such as strong sensors on board that stop operation when in contact with people or animals,” Brown explains. The IVG works closely with manufacturers on further development. “Some systems that also benefit hedgehog protection are already in the pilot or test phase.”
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What do animal welfare advocates advise robotic mower owners?
Since hedgehogs are crepuscular and nocturnal, the robotic mower should remain off during this time. “Ideally, let the mower run in the morning or in the afternoon before it gets dark,” advises Kolberg. However, only under supervision. “This should never happen at night.” This also applies in the fall. “Young hedgehogs can be born as late as September and are therefore potentially at risk throughout almost the entire growing season.” While males usually go into hibernation in October, this happens a bit later for females. Late-born young hedgehogs are sometimes still foraging during the day in December, “because the animals must reach at least 500 grams in body weight to survive hibernation,” says the animal welfare advocate.
How should robotic mower owners behave?
Annika Lange, wildlife conservation officer from the LBV, recommends to all robotic mower owners, in response to a query from myHOMEBOOK, to follow these tips:
- Since hedgehogs, like many other affected small animals, are nocturnal, the robotic mower should not be used from dusk onward.
- Mowing should never be done under hedges and bushes, as many animals hide there and the thicket serves as protection for them. If this is necessary, the entire section must be thoroughly inspected to avoid injuring animals.
- The entire garden should be thoroughly searched for small animals before use.
- The robotic mower should never run longer than absolutely necessary.
myHOMEBOOK opinion:
“The natural habitat for hedgehogs is threatened—by the intensification of agriculture and the development of open spaces, but also by modern technologies like robotic mowers. The garden is often the last refuge for hedgehogs. For the sake of nature, we should mow the lawn only as often as necessary. This not only helps hedgehogs but also other animals such as bees. And a natural garden offers valuable habitats for wildlife and plants, benefiting humans in the long run.”