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Are we seeing a spike in urban hedgehogs?

hedgehog (Erinaceus europaeus) eating apples on lawn
Hedgehogs love windfall apples Credit: Arterra Picture Library / Alamy 

All the evidence points to a big decline in hedgehog numbers over the past 50 years or so. The good news is that the decline in urban hedgehogs appears to have slowed, and there are even signs that they may be increasing in towns and cities. Since the main habitat used by hedgehogs in towns is private gardens, that means gardeners who want to help them (which is surely all of us) have a big responsibility.

So what makes a hedgehog-friendly garden? Before we can even start to answer that question, we need a reliable method of detecting hedgehogs. A team from Reading University set out to answer both questions, and their results were published in the journal Urban Ecosystems.

Hedgehogs were detected by issuing volunteer gardeners with footprint-tunnels, which use a food bait to lure animals across an ink pad so that their distinctive footprints are recorded on a removable sheet of paper. Over two years, they monitored more than 200 back gardens in Reading, and found hedgehogs in about 32-40 per cent of them (not all gardens were included in both years, and results were slightly different).

How good were gardeners at knowing whether they had hedgehogs in their gardens? The answer is not completely useless, but not very good either. In 13 per cent of gardens, hedgehogs were recorded where the owners hadn’t noticed them, while in 22 per cent they were not recorded where householders thought they were present. So gardeners were wrong about whether they had hedgehogs or not just over a third of the time.

This wasn’t a surprise; in a previous study in Gloucestershire, also using footprint-tunnels, hedgehogs were recorded in 35 per cent of gardens where householders had reported seeing them previously, but were also recorded in 38 per cent of gardens where the householder had not.

Unfortunately, this study failed to shed much light on what makes a hedgehog-friendly garden. Although volunteers completed a questionnaire about garden features that might affect hedgehogs, including type of house, presence of a pond, compost heap or log pile, use of slug pellets, etc, none of these was related to hedgehog presence.

The only thing that came close to significance was that hedgehogs were less likely to be found in gardens frequented by badgers; hardly surprising, since badgers are hedgehogs’ only serious predator. In contrast, hedgehogs don’t seem to care about either dogs or foxes. One limitation of this study, and indeed any study that measures only hedgehog presence, is that hedgehogs travel long distances while foraging. So, although they might well stop long enough to hoover up the bait in a footprint-tunnel, they might only be passing through. Finding out where hedgehogs actually spend most of their time would mean fitting them with radio or GPS trackers, which has yet to be attempted with urban hedgehogs.

A final point is that although the volunteers in this study were selected independently of whether they thought they had hedgehogs or not, all the study gardens were at least potentially accessible to hedgehogs, via holes under fences, gates or gaps in boundaries. Inaccessible gardens weren’t included, and the best – and simplest – thing you can do for hedgehogs is to make sure they can get in and out of your garden.

Don’t forget that even if your garden isn’t your local hedgehogs’ favourite, it might be blocking access to one that is. So if your garden is surrounded by a fence with no holes in, please go and make one, or more than one. In fact, do that now, before you forget.

  • Ken Thompson is a plant biologist with a keen interest in the science of gardening. He writes and lectures extensively; his most recent book is Darwin’s Most Wonderful Plants. Visit books.telegraph.co.uk