Wild animals fact-checked: human-made dangers and what studies show

Recreational hunters like to blame predators for the decline of hedgehogs and ground-nesting birds. This dossier shows what research demonstrates about human-made dangers to wild animals.

Editorial team Wild beim Wild · 26 October 2026

Common toad sitting on a road at night, car lights in the background

Photo: Simon Infanger / Unsplash

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As of 26 October 2026.

Robotic lawnmowers and garden tools
Leaf blowers and leaf vacuums
Mowing meadows and embankments
Fences and electric netting
Road traffic
Light at night
Fireworks
Glass
Insect decline
How we work with studies

Hedgehogs, amphibians, birds and insects do not disappear on their own. A large share of the dangers wild animals face today are human-made: garden tools, machines on meadows, fences, roads, light, noise and glass. This dossier collects studies and official figures on what these factors demonstrably cause, and assesses where the findings are strong and where data are lacking.

This page complements our study dossier «Hunting Fact-Checked», which deals with the consequences of recreational hunting. Both topics are connected: when recreational hunters justify the Fox hunting by citing the protection of hedgehogs, ground-nesting birds or brown hares, they ignore what research shows about the actual causes of the decline. In classifying the hedgehog as “near threatened”, the International Union for Conservation of Nature (IUCN) cites intensive agriculture, roads and urban sprawl, not predators. More on this in the dossier “Recreational hunters regulate, not predators”.

Robotic lawnmowers and garden tools

Hedgehogs do not reliably flee from robotic lawnmowers; many freeze or curl up. Rasmussen et al. (2021, Animals) tested 18 robotic lawnmower models in collision tests with dead hedgehogs. None detected the smallest juveniles under 200 grams, and with larger animals detection only occurred after physical contact. Some models caused serious injuries, while others left no injuries. A follow-up study by the University of Oxford involving 19 commercially available models reached the same conclusion: with one exception, all devices had to touch the hedgehog in order to notice it.

Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) analysed 370 reported cases of cut injuries to hedgehogs over 16 months, caused by electric garden tools, primarily robotic lawnmowers. 47 per cent of the animals did not survive. String trimmers and brush cutters are also dangerous: according to the experience of the Igelzentrum Zürich, it actually receives more hedgehogs with string-trimmer injuries than with suspected robot injuries.

Relevance to Switzerland: The hedgehog is on the Red List and is Animal of the Year 2026. A night-time ban on robotic lawnmowers, as exists in Cologne and other German cities, does not exist in Switzerland. In Bern and St. Gallen, corresponding motions failed; in Basel-Stadt a motion is pending. Background: Robotic lawnmowers kill hedgehogs: German cities ban night-time operation, Bern and St. Gallen wave it away.

Leaf blowers and leaf vacuums

There is as yet hardly any research on leaf blowers that quantifies direct losses of animals. The British insect researcher Simon Leather found no study measuring this in a literature review. By contrast, the importance of the leaf layer is well documented: it serves as winter quarters, a food source and a hiding place for insects, spiders, worms, amphibians and hedgehogs. Anyone who blows or sucks it away removes this habitat.

Research on mowing shows how severely suction technology affects small animals: in a study by Hemmann et al. (1987), around 84 per cent of the bugs and larvae recorded were killed or injured by suction mowers at roadsides, and about half by the finger-bar mower (overview in van de Poel and Zehm). The Swiss Animal Protection STS warns that leaf vacuums can fatally injure animals, and points to noise levels of 90 to 120 decibels, as loud as a chainsaw.

On wildbeimwild.com: Leaf blowers drive hedgehogs from their homes, Leaf blowers belong in the scrapheap and Leaf piles for biodiversity.

Mowing meadows and embankments

Solid research exists on mowing, including from Switzerland. Researchers from Agroscope and ETH Zurich (Humbert et al. 2009, Agriculture, Ecosystems & Environment) evaluated how mowing techniques affect fauna. Depending on the machine, roughly a tenth to a third of the small animals in an area die in a single mowing pass. If the entire hay harvest, including tedding, windrowing and loading, is taken into account, losses among grasshoppers were 65 to 85 per cent (Humbert et al. 2010). Mower-conditioners increase the damage considerably.

For amphibians, cutting height is decisive: at 7 to 8 centimetres, 24 to 27 per cent of the animals were killed or injured, at 11 to 14 centimetres only around 3 per cent (Classen et al. 1996). All figures come from the overview by van de Poel and Zehm, which also points out the small sample sizes of individual studies.

Fences and electric netting

Electric netting and poorly maintained fences become traps for hedgehogs, amphibians, roe deer, red deer and birds. Animals get tangled in the mesh, hedgehogs bite into live wires, and amphibians receive fatal shocks in damp grass. In Grisons, 73 cases of entangled wild animals have been recorded so far in 2026. There is no nationwide statistic on fence victims.

Take action: Our petition “Pasture nets must not be death traps for wild animals” calls for a removal obligation, inspections and strand fences instead of netting. For cantonal parliaments there is the template text «Animal-welfare-compliant fencing and electric netting requirements».

Road traffic

Grilo et al. (2020, Frontiers in Ecology and the Environment) estimate that on Europe's roads around 194 million birds and 29 million mammals are killed every year. The researchers found particularly high collision rates for blackbirds and hedgehogs. For rare species with low population density, even a small number of accidents can accelerate local extinction.

Link to recreational hunting: In its report on autumn wildlife accidents, Mobiliar also names hunting-related stress as a contributing cause. More on this: Autumn wildlife collisions: hunting stress also named as a contributing cause and Clock change: why the week after 25 October is dangerous for wild animals.

Light at night

A study by the University of Bern shows that artificial light disrupts nocturnal pollination. Knop et al. (2017, Nature) studied meadows in the Bernese pre-Alps. On meadows with LED street lamps, insects made 62 per cent fewer nocturnal flower visits than on unlit areas. The cabbage thistles on illuminated meadows produced around 13 per cent less fruit. According to the University of Bern, daytime pollinators cannot make up for this loss.

Fireworks

Hoekstra et al. (2023, Frontiers in Ecology and the Environment) used weather radar in the Netherlands to measure how birds react to New Year's Eve fireworks. On New Year's night, on average 1,000 times more birds were in the air than on ordinary nights. The effect was strongest within the first 5 kilometres, and up to 10 kilometres away at least ten times as many birds were still flying. Larger birds such as geese and ducks climbed to hundreds of metres in altitude and stayed airborne for up to an hour, in the middle of winter, when every energy reserve counts.

Relevance to Switzerland: On 29 November 2026, Switzerland votes on the fireworks initiative. Background: Fireworks initiative on 29 November: what's at stake for wild animals and Fireworks bans in Switzerland.

Glass

Glass surfaces are among the biggest causes of death for birds in built-up areas. Loss et al. (2014, The Condor) estimated 365 to 988 million birds per year dying from building collisions in the USA. For Switzerland, the Swiss Ornithological Institute in Sempach assumes millions of birds per year. There is no exact Swiss figure.

Insect decline

Insects are the food base for hedgehogs, birds, bats and amphibians. Hallmann et al. (2017, PLOS ONE) documented a decline of more than 75 per cent in the biomass of flying insects in German protected areas over 27 years. The measurements were taken in protected areas, that is, precisely where conditions should be at their best. The authors suspect the main cause lies in the intensive agriculture surrounding the protected areas, for instance through pesticides.

How we work with studies

For every claim we give the source and, where possible, the original study. Where we rely on review articles, we say so. The strength of the evidence varies: there are robust studies on robotic lawnmowers, mowing, roads, light, fireworks and glass. For leaf blowers, measurements of direct losses are lacking, and for Switzerland systematic figures are missing on almost every topic, such as statistics on fence victims or on hedgehogs with cut injuries.

This page is updated on an ongoing basis. We welcome tips about new studies.

More on the subject of recreational hunting: What the research says about this is shown by Hunting fact-checked: the state of research.

The position of IG Wild beim Wild: IG Wild beim Wild rejects recreational hunting. Our model is the canton of Geneva, which has managed without recreational hunting since 1974: without hunting seasons, without hunting dogs, without driven hunts, without high seats, without the animal cruelty and crime that go hand in hand with hunting season elsewhere. What has worked there for over fifty years disproves every position paper by JagdSchweiz. An association that bases its policy on claims it refutes in its own documents is not a professional organisation, but a factory for misinformation.

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