Night-time collisions with robotic lawnmowers are a significant animal welfare and conservation problem for hedgehogs as these often suffer serious or even fatal injuries. In order to make the operation of robotic lawnmowers hedgehog-safe, the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), the specialist crash test company CTS and the computer magazine c't are developing special hedgehog dummies and standardised tests to prevent fatal collisions. National and international experts will be discussing the latest developments in this project and many other topics related to hedgehog research, animal welfare and conservation at two conferences organised by the Leibniz-IZW in Berlin from January 16 to 19, 2025.

In October 2024, Leibniz-IZW, CTS and c't carried out tests on prototypes of hedgehog dummies to assess their similarity to real hedgehogs. These dummies should not necessarily look like real hedgehogs to the human eye, but should “behave” identically when a robotic lawnmower approaches and collides with them, so that realistic and standardised safety tests for the mowers can be carried out. In the test series, the team compared a prototype developed by CTS with real, already deceased hedgehogs collected at the Leibniz-IZW. The dummies have a 3D-printed internal skeleton, can be heated to hedgehog body temperature, have different sizes and shapes (curled and uncurled) and resemble hedgehogs as closely as possible in appearance, weight-to-size ratio, mobility and flexibility – so that in future they can be used in tests on all robotic mower models regardless of their object detection sensor technology (laser, ultrasound, optical, thermal imaging or contacts in the bumper) to assess the extent to which these models can recognise hedgehogs. Accurate design, correct weight and stability are essential, especially for mechanical detection with impact sensors. In addition to testing the detection of hedgehogs, the injuries of the hedgehog carcasses and the dummies in the event of identical (forced) robotic mower accidents were analysed.

“The tests revealed a close resemblance between the injuries of the hedgehog carcasses and the dummies during the forced collisions”, says hedgehog expert Dr Anne Berger from the Leibniz-IZW. “However, the dummies are still a little too heavy and inflexible compared to real hedgehogs and will still undergo some improvements in the coming months. The team will carry out final tests again in spring 2025 and finalise the dummies.” Berger and her colleagues at CTS and c't are working towards the introduction of an SI-DIN standard in Germany, which would make standardised crash tests for robotic lawnmowers with these dummies mandatory for all brands and models on the market. The tests will demonstrate the extent to which each robot mower model is able to reliably detect hedgehogs and initiate evasive manoeuvres or emergency braking.

In the past, Berger and her colleagues have conducted extensive empirical investigations on hedgehog cuts caused by robotic lawnmowers. For example, they analysed 370 cases of cut injuries reported throughout Germany and found that their occurrence was evenly distributed across the days of the week. “This is a clear indication that robotic lawn mowers are often the cause of these injuries, as these devices are the only ones that can legally be used on a Sunday”, says Berger. Almost half of the animals found and reported (at 47%) did not survive the injury. Hedgehog rescue centres also report a steady increase in the number of cases of injured hedgehogs, which indicates a growing conservation problem in the context of declining hedgehog populations in Germany. “We furthermore suspect that a high number of cases of injured or deceased hedgehogs are not even found or reported”, says Berger.
As hedgehogs sometimes have to live for a longer period of time with the injuries they suffer and such animal suffering is prohibited by law – provided there are alternatives that do not cause the same level of pain or harm – scientists such as Berger are working with partners in Germany and elsewhere to develop such alternatives. One of these are robotic mowers, which can and must prove in standardised tests that they can reliably detect hedgehogs and avoid them.

However, there are also other promising – and even faster ways – to improve the protection of hedgehogs, says Berger. A ban on the use of robotic lawnmowers at night, as some local authorities in Germany have already implemented, would significantly reduce the risk to hedgehogs. Unsupervised operation at night is particularly dangerous for hedgehogs, as they are nocturnal and do not run away from danger, but remain stationary and as quiet as possible. If they are run over and are injured by the robots, they will – if they still can – silently seek the protection of hedges and bushes so as not to attract the attention of predators, for whom they would then be easy prey. Unfortunately, even minor cuts can lead to severe inflammation or the laying of fly eggs in the wounds later and thus, if left untreated, to death.

From January 16^th to 19^th, 2025, national and international hedgehog experts will meet for two conferences at the invitation of the Leibniz-IZW in Berlin. The “10th Meeting of the European Hedgehog Research Group” on 16 and 17 January will focus on new research perspectives on hedgehogs, for example on genetics, diseases and parasites, as well as on risks, population development and conservation. This will be followed on January 18 and 19 by the „2. Austausch- und Weiterbildungs-Veranstaltung für Igel- und Wildtierpflegestationen“, an exchange and training meeting for German hedgehog and wildlife care stations at which topical practical problems in the care of hedgehogs and other wildlife will be discussed and scientific information provided. The meeting also serves to improve networking amongst the various hedgehog and wildlife rescue centres in German-speaking countries and thus increase the impact of each individual centre's work to protect the animals.

The latest findings from the dummy crash tests by Leibniz-IZW, CTS and c't will be presented to the community at the conferences and discussed with the experts present. At the next meeting of the hedgehog community from Germany and Europe, DIN-certified safety tests may already be a topic of the sessions.