Common Ground Suffolk, The gardener's guide to hedgehogs

A hedgehog foraging through fallen leaves in a garden at dusk, its spines visible and snout close to the ground — The European hedgehog (*Erinaceus europaeus*) – Britain’s only spiny mammal, and one of its most threatened

Activity period April – October

Benefit to garden Pest control

Habitat needed Connected green space

Conservation status Vulnerable

A hedgehog visits your garden for one reason: food. Every night from April through to October, it will travel up to two kilometres through gardens, hedgerows, and rough grass, hunting beetles, earwigs, caterpillars, slugs, and earthworms with extraordinary efficiency. A single hedgehog can eat up to 100 invertebrates in a single night, and around 160 grams of insects and worms every day.

That is a remarkable amount of pest control, delivered quietly, organically, and entirely free of charge. It is also, increasingly, something that most gardens will never see. Britain’s hedgehog population has collapsed within living memory, and the reasons are almost entirely things that happen in and around our gardens.

An estimated 30 million hedgehogs lived in Britain in the 1950s. Today, fewer than 900,000 remain – a decline of over 97% in less than a lifetime.

What hedgehogs actually eat

Hedgehogs are insectivores, though “invertebrate generalist” is more accurate. Their diet is dominated by whatever is most available on any given night, and the variety is striking. Studies of wild hedgehog droppings have found the remains of 32 earwigs in a single dropping, and 15 in another. Beetles and earwigs make up the bulk of the diet by volume across the year, with earthworms, caterpillars, slugs, snails, and millipedes making up much of the rest.

Slugs are a notable part of the diet, though they are not the primary food source that popular imagination suggests. Research indicates they make up around 10% of what a hedgehog eats. In practice, a foraging hedgehog is a broad-spectrum pest controller: it hunts the things that eat your plants, the things that eat the things that eat your plants, and the things that break down organic matter in the soil. Its presence is a reliable signal of a healthy, invertebrate-rich garden.

Why the decline happened

Rural hedgehog populations have declined by between a third and three-quarters nationally since 2000, with eastern England experiencing some of the largest losses. The causes are multiple and interconnected, but most of them trace back to two things: the loss of connected green space, and the impoverishment of the invertebrate food supply.

In the countryside, the removal of hedgerows, field margins, and rough grassland has stripped away the habitat hedgehogs depend on. The widespread use of pesticides has reduced the insect and worm populations they feed on. In gardens, the trend towards hard landscaping, close-boarded fencing, and meticulously maintained lawns has made many urban and suburban areas effectively impassable.

Roads are a constant and significant pressure. An estimated quarter of the entire UK hedgehog population is killed on roads each year. A hedgehog’s natural defence when threatened is to curl into a tight ball, which works well against foxes and badgers. It is of no use whatsoever against a car.

50%

Rural hedgehog populations have fallen by at least half since 2000. In urban areas the picture is more stable – a sign that gardens can and do make a real difference.

The single most important thing: connected gardens

A hedgehog needs to roam. Its home range can span anywhere from 10 to 50 hectares, and it moves through that space every night in search of food. A single garden is nowhere near large enough to sustain one. What it needs is access to a network of gardens, and the biggest barrier to that is the solid, close-boarded fence.

The solution is simple and takes about ten minutes. Cut a 13×13cm hole at the base of your fence panel, roughly the size of a CD case. That is large enough for any hedgehog to pass through, and small enough to prevent foxes doing the same. Ask your neighbours to do the same, and you create a corridor. Research by the People’s Trust for Endangered Species found that connecting just five gardens in a row doubles local hedgehog survival rates.

More than 120,000 hedgehog highways have been registered across the UK, connecting around 240,000 gardens. You can register yours at hedgehogstreet.org, where it is added to a national map of connected garden networks. The campaign is run jointly by the People’s Trust for Endangered Species and the British Hedgehog Preservation Society, and it is the largest citizen conservation effort currently running for any British mammal.

Creating habitat in your garden

Once a hedgehog can get in, it needs somewhere to sleep during the day, and somewhere safe to hibernate from November through to March or April. Hedgehogs are opportunists: they will use log piles, leaf piles, dense bramble patches, gaps under sheds, and purpose-built hedgehog houses.

Log and leaf piles

A pile of logs in a quiet corner of the garden, roughly 50cm high and one metre wide, provides both daytime shelter and a foraging site. Logs harbour beetles, woodlice, centipedes, and other invertebrates that hedgehogs prey on. A pile of autumn leaves stacked against a fence or under a hedge is used readily as a hibernation site, and costs nothing. Leave it undisturbed from October through to April.

Hedgehog houses

A purpose-built hedgehog house with a tunnel entrance consistently outperforms open log piles for hibernation, because the tunnel prevents disturbance from cats, foxes, and badgers. The entrance tunnel should be around 13cm wide. Position the house in a shaded, quiet corner, facing away from prevailing winds. Fill it loosely with dry leaves and leave it completely alone once a hedgehog has taken up residence. Gardens with a well-sited house have recorded hedgehog use in seven out of ten consecutive winters.

Whether you buy or build one, resist the temptation to check inside during hibernation. A disturbed hedgehog burns through its fat reserves waking up, which can be fatal in a cold winter.

Hazards to remove from your garden

Several common garden practices and materials cause serious harm to hedgehogs, most of which are easily avoided once you know what to look for.

Slug pellets. Metaldehyde slug pellets are now banned for outdoor use in Great Britain, but old stock still exists in many garden sheds. Dispose of any you have at a household recycling centre. Even ferric phosphate pellets, which are permitted under organic standards, reduce the slug population that hedgehogs depend on. A garden managed for hedgehogs needs no slug pellets at all.
Strimmers and lawn mowers. Hedgehogs sleep through the day in dense grass, leaf piles, and borders. A strimmer moving through long grass will often find one before you do, and the hedgehog’s instinctive response is to curl up rather than run. Always check carefully before strimming, and consider leaving any areas of long grass completely uncut until autumn.
Bonfires. A pile of garden waste built up over days or weeks is an attractive hibernation site. Never light a bonfire that has been sitting built up for more than a day. Either build it and light it immediately, or deconstruct the pile and move it just before lighting. Light it from one corner only to give any wildlife a chance to escape.
Netting. Pea netting, fruit cage mesh, and loose garden netting left at ground level is one of the most dangerous things a hedgehog encounters. Their spines mean they cannot reverse out of netting once caught, and their response to panic is to roll tighter, which worsens the entanglement. Raise netting off the ground at night or remove it entirely when not in use.
Robotic mowers. These operate at night, precisely when hedgehogs are active. Many current models have no reliable hedgehog detection. If you use one, restrict its operating hours to early evening and always confine it to a well-lit, open area away from rough grass and borders.
Ponds and steep-sided holes. Hedgehogs swim well but cannot climb out of steep-sided ponds or drainage holes. Add a ramp, a pile of stones, or a piece of chicken wire as a permanent escape route to any pond with vertical edges. Cover drains and deep holes.
Compost heaps. Warm, covered compost heaps are popular nesting sites. Before forking a compost heap, probe it gently and check carefully. A hedgehog in a compost heap in October or November may be beginning hibernation.

Food and water

Supplementary feeding is most valuable in early autumn, when young hedgehogs born late in the season are still trying to reach the weight they need to survive hibernation (around 600g). A hedgehog that goes into hibernation underweight is unlikely to emerge in spring.

Put out a shallow dish of meat-based wet dog or cat food, or dry cat biscuits, in a sheltered spot around sunset. Place it in a simple feeding station: an upturned box or wooden crate with a 13cm entrance hole keeps cats and foxes out while letting hedgehogs in. Clean the dish daily and do not leave uneaten food down overnight.

A shallow dish of fresh water is just as important as food, particularly during dry periods when earthworms and other invertebrates retreat deeper into the soil. Hedgehogs are lactose intolerant, so never leave out milk, despite the old tradition of doing so. Bread is also best avoided: it has almost no nutritional value for them.

How to tell if hedgehogs are visiting

The clearest sign is droppings: black, slightly shiny, and around 2–3cm long, usually left in the middle of a lawn or path rather than hidden away. A hedgehog dropping often contains the recognisable remains of beetles, with fragments of hard wing cases visible.

The sound comes before the sight. Hedgehogs are surprisingly noisy foragers, snuffling and rustling through leaf litter in a way that seems improbably loud for an animal their size. If you hear something moving through your borders on a warm evening from April onwards, it is worth standing quietly and waiting. A hedgehog absorbed in hunting rarely pays much attention to a still human.

A wildlife camera set at ground level near a log pile, feeding station, or hedgehog highway is the most reliable way to monitor whether your garden is being used, and by how many individuals. The Hedgehog Street campaign asks gardeners to submit sightings to their national map, which helps track population trends across the country.

Legal protection

Hedgehogs are protected under Schedule 6 of the Wildlife and Countryside Act 1981, which makes it illegal to kill or capture them using certain methods, and under the Wild Mammals Protection Act 1996, which prohibits deliberate cruelty or mistreatment. They are also listed under Section 41 of the Natural Environment and Rural Communities Act 2006 as a species of principal importance for conservation in England, which means public authorities are required to consider their conservation needs when making decisions.

If you find a hedgehog out during the day, or one that appears injured, lethargic, or very small, contact the British Hedgehog Preservation Society on 01584 890 801. Daytime activity is almost always a sign that something is wrong.

The Gardener’s Guide to Hedgehogs