Your pet hedgehog
shouldn’t hibernate
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Does a hedgehog forget you after it hibernates? Fresh out of its winter sleep, a hedgehog may curl up and huff at your touch. But here's what matters more: most pet hedgehogs shouldn't be hibernating at all.
First, let's spend a winter with a wild hedgehog. When it turns cold, it rolls itself into a ball. Its heart slows from 190 beats a minute to about 20. Its body drops from 35 degrees to below 10.
Its brain goes into power-saving mode too. Nerve cells in the brain look like little trees, with tiny buds all along their branches. In hibernating ground squirrels, scientists saw these buds shrink by a fifth to a third, like a tree losing its leaves in winter.
But the trunk and the branches stay put. Once it wakes up, most of the buds grow back within about two hours. These buds are called dendritic spines. Nerve cells link up through them, and much of what we remember lives in those links.
So once they grow back, is the old memory still there? One experiment tested exactly that: bats first learned which of three paths hid a snack. After two months of hibernation, they found it just as well as bats that stayed awake.
Not every result agrees: some ground squirrels forget part of a trick they had just learned. Nobody has run this test on hedgehogs yet. But judging by these animals, forgetting everything after one winter is unlikely. So why does it act like it doesn't know you?
Hedgehogs see poorly. They know people mostly by smell. Just after waking it's cold, hungry and groggy, so it curls up at any touch. That's self-defense, not forgetting. Now back to the more urgent part.
Most pet hedgehogs are African pygmy hedgehogs. They come from warm Africa, and animal welfare groups warn: don't let a pet one hibernate. Below about 18 degrees, one can slip into a false hibernation: cool to the touch, not eating, limp and still. That isn't sleep. Left too long, it can be deadly.
If you see this, warm it up slowly, then get it to a vet quickly and follow their advice. Day to day, keep its cage between 24 and 30 degrees. Want it to know you faster? Put an old shirt you've worn into its bed.
A week later, give it a stroke. Does it still curl up?
A winter’s sleep:
the brain’s little trees drop buds
When a hedgehog hibernates, its heart slows from about 190 beats a minute to around 20, and its body drops from 35 °C to below 10 °C. The brain saves power too.
Nerve cells in the brain look like little trees covered in tiny buds. In hibernating ground squirrels, 20–30% of those buds shrink away, like a tree losing leaves in winter. But the trunk and branches stay.
Two hours after waking,
the buds grow back
These buds are called dendritic spines: small bumps sticking out of a nerve cell. Nerve cells link up through them, and a big part of memory lives in those links.
Do the regrown buds
still remember?
Nobody has run this test on hedgehogs yet. Judging from these animals, forgetting everything after one winter is unlikely.
So why does it act
like it doesn’t know you?
More important:
don’t let it hibernate
fall into false hibernation Pet hedgehogs are mostly African pygmy hedgehogs, from warm Africa. Animal welfare groups warn: don’t let a pet one hibernate. In a cold room it may go into false hibernation: cold to the touch, not eating, limp. It isn’t sleeping, and it can be deadly if it goes on.
If that happens, warm it up slowly, take it to a vet as soon as you can, and follow the vet’s advice. Keep the cage at 24–30 °C (75–86 °F).
Quick check
A hedgehog curls into a ball when you touch it right after waking. Why, most likely?
The brain's buds mostly regrow within two hours and the trunk never left; curling up is self-defense, not forgetting.
