Britain's only spiny mammal, the hedgehog (*Erinaceus europaeus*, the West European hedgehog) is one of the country's best-loved wild animals — and one of its most rapidly declining. Once a common sight in gardens, hedgerows and farmland, it is now classified as vulnerable to extinction in Britain. ## The animal A hedgehog is covered in around 5,000 spines, each one a modified, hollow hair. When threatened it draws on a powerful muscle running around the edge of its body to roll into a tight, prickly ball — its main defence against predators such as badgers and foxes. Spines are moulted and replaced gradually throughout life. Adults usually weigh somewhere between 600g and 1,200g, varying greatly with the seasons as they fatten for winter. ## Behaviour Hedgehogs are nocturnal, emerging at dusk to forage and often covering a mile or more in a single night — males roam furthest, especially in the breeding season. This need to travel is central to their survival, and it explains why garden boundaries matter so much (see below). Their diet is made up mostly of invertebrates — beetles, caterpillars, earthworms and other ground-dwelling insects — which has earned them the affectionate title of "the gardener's friend". Slugs and snails form a smaller part of the diet than many people assume, and can carry lungworm, a serious hedgehog parasite. From roughly November to March or April, hedgehogs hibernate, building a tightly packed nest of leaves called a hibernaculum and living off the fat reserves laid down in autumn. They rouse, and sometimes shift nest, several times over winter. A hedgehog must be heavy enough — generally reckoned to be at least 450–600g — to survive hibernation, which is why underweight "autumn juveniles" so often need a helping hand. Breeding runs from spring into late summer. Courtship involves the male circling the female for hours, with much snorting and huffing. A litter is usually four or five hoglets, born blind and with soft, white spines just beneath the skin. Hedgehogs live two to three years on average in the wild, though they can reach seven or more. One of their odder habits is self-anointing: on meeting a strong new smell or taste, a hedgehog will produce frothy saliva and contort itself to spread it across its spines. The reason behind it is still not fully understood. ## Why hedgehogs matter As natural predators of garden invertebrates, hedgehogs help keep populations of pest species in balance with no chemicals at all. They are also a useful indicator species: a garden or landscape healthy enough to support hedgehogs is generally healthy enough to support a great deal of other wildlife. Their decline is, in effect, a warning sign about the state of the wider countryside. ## A species in decline Hedgehogs were once abundant — a much-quoted, if rough, estimate suggested perhaps 30 million in Britain in the 1950s. Today the population is thought to number well under a million. The *State of Britain's Hedgehogs* reports, produced by the British Hedgehog Preservation Society and the People's Trust for Endangered Species, show that rural populations have fallen sharply — by somewhere between a third and three-quarters since 2000 — while urban populations, though also reduced, show tentative signs of stabilising. In 2020 the hedgehog was listed as **vulnerable to extinction** on the first official Red List for British Mammals. The causes are many and interlinked: intensive agriculture and the loss of hedgerows and field margins; habitat fragmentation; busy roads; pesticides and slug pellets, which both poison hedgehogs directly and strip away their insect prey; and, in towns, the steady replacement of gardens with paving, decking and solid, impermeable fencing. Tidy, sealed-off gardens leave hedgehogs nowhere to feed, nest or pass through. Everyday garden hazards — strimmers, bonfires, netting, uncovered drains and steep-sided ponds — take a further toll. ## Helping hedgehogs in the garden Gardens, taken together, form a vast potential refuge — and small changes make a real difference. Helping hedgehogs is one of the simplest ways to put nature-friendly, [[Garden Kind|wilder gardening]] into practice: - **Make a Hedgehog Highway.** Cut a 13cm x 13cm (roughly 5 inch) gap at the base of fences and walls so hedgehogs can roam freely between gardens. - **Leave a wild corner.** Log piles, leaf litter and rough grass provide both food and nesting sites. - **Choose hedges over solid fences** where you can — they are permeable and far richer in habitat. - **Stop using slug pellets and pesticides.** They remove the hedgehog's food and can poison it outright. - **Check before you cut or burn.** Always check long grass before strimming or mowing, and check (or build on the day) any bonfire before lighting it. - **Make water safe.** Give ponds a sloping edge or an escape ramp, and cover open drains. - **Offer food and water** if you wish: meaty cat or dog food and a dish of fresh water — never bread and milk, as hedgehogs are lactose intolerant. - **Add a hedgehog house** for nesting and hibernation, tucked into a quiet, sheltered spot. - **Drive carefully at dusk**, especially on lanes near hedgerows. ## Conservation and recording The main UK conservation effort is Hedgehog Street, run jointly by the British Hedgehog Preservation Society and the People's Trust for Endangered Species, which coordinates the Hedgehog Highway campaign and encourages people to log sightings on the BIG Hedgehog Map. Local rescues and carers take in sick, injured and underweight hedgehogs, particularly autumn juveniles too small to survive the winter. Reporting sightings — alive, or sadly dead on roads — helps build the national picture of how the species is faring. ## In folklore The name itself describes the animal: a "hog", for its pig-like snout and snuffling, of the "hedge". Hedgehogs run throughout British folklore, from the old myth that they steal milk from cows to Beatrix Potter's washerwoman Mrs Tiggy-Winkle — a measure of how deeply they are woven into the country's affections. ## Further reading The note above draws on a body of work by leading hedgehog writers and researchers: Pat Morris's *Hedgehogs* and the updated *The New Hedgehog Book*; Hugh Warwick's *The Hedgehog Book*, *A Prickly Affair: My Life with Hedgehogs* and his *Hedgehog* in the Reaktion Books Animal series; *Hedgehogs in the Landscape* by Henry Johnson and Alison Foy; and the essay collection *The Hedgehog Predicament*. `Knowledge Base:` [[Animals]], [[Ecology]]