Robot mowers and hedgehogs

Hedgehogs feed from dusk to dawn, and when they're threatened they curl up rather than run. A mower working unattended in the dark can't see one coming. The good news is that the main fix is simple and costs nothing: only run your mower in daylight.

The short answer

• Run your robot mower in daylight only, never from dusk to dawn. The British Hedgehog Preservation Society recommends this.
• Check the lawn before the mower starts, especially in long grass and along hedges.
• Don't rely on a mower's sensors to spot a hedgehog: in the published research, none of the models detected young hedgehogs.

What the research found

A study led by researchers at Oxford and Aalborg universities, funded by the BHPS and published in 2023, ran a range of robot mowers against hedgehog cadavers to see what happened. Its main findings were:

• some models caused serious damage and others didn't
• none of the models detected juvenile hedgehogs
• features such as pivoting blades, skid plates and front-wheel drive were linked to a better safety index

The study looked at specific models in controlled conditions. It doesn't tell you how any other model would do, and we don't rate wildlife safety ourselves. Read the paper and the BHPS summary, linked in the sources below.

Setting a daylight-only schedule

Most mower apps let you set the hours it runs. Start it after sunrise and finish before sunset, with a margin either side: hedgehogs can still be about at first light and in the early evening. Our daylight schedule tool, coming soon, works out a window for your location and month.

Making your garden friendlier for hedgehogs

• leave a wild corner or a log pile where the mower doesn't go
• make a small gap in fences so hedgehogs can move between gardens
• check under hedges and in long grass before the mower's first run of the season

The RHS has more ideas on hedgehog-friendly gardening.

FAQs

Are some robot mowers safer for hedgehogs?

The research found differences between models, and linked some design features to a better safety index. It didn't test every model on sale, and none detected young hedgehogs, so daylight-only mowing is the advice whatever you buy.

Do hedgehogs come out in the day?

They're mostly out from dusk to dawn. If you see one out in daylight, the BHPS has advice on what to do.

What about frogs and other wildlife?

The same steps help: daylight mowing, a quick check of the lawn first, and a wild corner left uncut.