# 12 Amazing Facts About Hedgehogs (5,000 Spines, and They Self-Anoint)

*Europe, Asia and Africa · JUL 25 2026*

> Hedgehogs carry around 5,000 hollow keratin spines, hibernate through winter, and perform self-anointing — chewing a strong-smelling substance and spreading frothy saliva across their spines for reasons still unexplained.

Self-anointing with frothed saliva, partial immunity to some venoms, and a British decline nobody planned. Twelve facts.

## What are the key takeaways from this briefing?
- Hedgehogs carry around 5,000 hollow keratin spines, which are modified hairs.
- Self-anointing — spreading frothy saliva over the spines — has no settled explanation.
- They are lactose intolerant; bread and milk causes serious harm.
- They roam over a mile a night, so fenced gardens fragment their range.
- A 13 cm gap at the base of a fence is among the most effective simple interventions.

## Twelve hedgehog facts, fact-checked

Hedgehogs are ancient insectivores and one of Britain's most-loved garden animals, in serious decline. Full profile in our [hedgehog guide](/wildlife-guides/hedgehog/).

### 1. About 5,000 spines

Modified hairs of keratin, hollow and each on a flexible base. They are not barbed and are not shed defensively.

### 2. Curling up is muscular

A powerful ring of muscle draws the spiny skin into a ball, protecting the soft underside.

### 3. They self-anoint

On meeting a strong smell or taste, a hedgehog chews it into frothy saliva and flicks it across its spines. No explanation is settled — camouflage, deterrence and parasite control have all been proposed.

### 4. They tolerate some venoms

Partial resistance to certain snake venoms, from a blood protein — the same trick seen in mongooses and honey badgers.

### 5. They are lactose intolerant

Bread and milk, long left out for them, causes serious digestive harm. Meat-based pet food and water are appropriate.

### 6. They travel over a mile a night

Roaming widely to forage, which is why fenced gardens fragment their range so badly.

### 7. Hibernation is not sleep

Body temperature and heart rate drop dramatically. Waking is costly, so disturbance in winter can be fatal.

### 8. Hoglets are born with soft spines

Beneath fluid-filled skin, so the mother is not injured. Spines harden within hours.

### 9. They can swim and climb

Which is why steep-sided ponds are a hazard — a hedgehog that cannot find a sloped exit drowns.

### 10. British numbers have fallen sharply

Habitat fragmentation, road deaths, tidy gardens, slug pellets and loss of hedgerow and rough ground have driven a steep decline.

### 11. Hedgehog highways work

A 13 cm gap at the base of a garden fence reconnects fragmented territory — one of the most effective simple interventions available.

### 12. Check before you strim or light a bonfire

Long grass and unlit bonfire piles are classic nesting sites. Checking first prevents a large share of avoidable deaths.

**[Read the full hedgehog wildlife guide](/wildlife-guides/hedgehog/)** for IUCN status, population context and sources — or **[donate to WARN](/donate/)** to help fund the partner teams protecting wildlife on the ground.

## What do people ask about this briefing?
### How many spines does a hedgehog have?
Around 5,000. They are modified hairs made of keratin, hollow and set on flexible bases. Unlike porcupine quills they are not barbed and are not detached defensively.

### What is hedgehog self-anointing?
On encountering a strong smell or taste, a hedgehog chews the substance into frothy saliva and flicks it over its own spines with its tongue. It is well documented and not well explained — camouflage, predator deterrence and parasite control have all been proposed.

### Should you give hedgehogs bread and milk?
No. Hedgehogs are lactose intolerant and milk causes serious digestive harm, while bread offers almost no nutrition. Meat-based cat or dog food and a shallow dish of water are appropriate.

### Why are hedgehogs declining?
Habitat fragmentation is central — hedgehogs roam over a mile a night, and enclosed gardens, roads and lost hedgerows cut territory into unusable pieces. Road deaths, slug pellets, tidy gardens with no shelter, and strimmer and bonfire deaths add to it.

### How can I help hedgehogs?
Cut a 13 cm gap at the base of your fence to reconnect gardens, leave a wild corner with leaf litter and log piles, avoid slug pellets, check long grass before strimming and bonfire piles before lighting, and make sure ponds have a sloped exit.

## Which sources does this briefing use?
- [IUCN Red List — Erinaceus europaeus](https://www.iucnredlist.org/species/29650/2791303)
- [IUCN Red List](https://www.iucnredlist.org/)

Human-readable page: https://worldanimalrescuenetwork.org/newsroom/hedgehog-12-amazing-facts/