Hedgehog houses: do they work, and where to put one

Often, yes. In the largest UK survey, owners reported hedgehogs using 81% of houses as summer day nests and 57% for hibernation. Put one in a shady, sheltered spot against a wall, fence or shrub, entrance away from open ground and not facing north or north-east. Choose untreated wood with a tunnel or inner wall.

First, the evidence, which is better than for most wildlife kit and less tidy than the headline numbers suggest.

What the evidence says, and what it doesn’t

The best data comes from the Hedgehog Housing Census, run through Hedgehog Street (a joint project of PTES and the British Hedgehog Preservation Society) and analysed by researchers at the University of Reading. Over 4,300 people reported on their houses. Of those who answered each question, they reported use for:

• Summer day nesting: 81%
• Winter day nesting: 66%
• Hibernation: 57%
• Breeding: 28%

Those are good numbers. Read them with three caveats, all of which Hedgehog Street states itself.

“Used” means “ever used”. People were asked not to disturb their houses and to watch with trail cameras or a stick across the entrance. So the survey can say a hedgehog went in at some point. Hedgehog Street says plainly that “the frequency at which houses were used could not be determined”.

The people who answered were not a random sample. Many were registered Hedgehog Champions, and 79% had put their house out only after seeing a hedgehog in the garden. A house in a garden that already has hedgehogs will show more use than one put out in hope.

Reporting bias is possible. People who feed hedgehogs, or who have had a house for years, may simply notice more.

So a house is a reasonable bet in a garden hedgehogs already visit. It does not bring hedgehogs into a sealed garden. As Hedgehog Street puts it, “without access into your garden, a hedgehog won’t use your hedgehog home”. Before buying anything, cut a 13cm × 13cm gap at the bottom of your fence (the BHPS size). The hedgehog page explains why that matters more than any house.

Where to put it

This is the part you control, and the census suggests it matters.

• Shady, quiet, sheltered and dry. The BHPS suggests against a wall, fence, hedge or shed. Hedgehog Street says “along boundaries, in back gardens and within 5m of the house”. Back gardens and sheltered spots came out ahead in the census.
• Under cover. The census authors advise placing it under bushes or shrubs.
• Entrance away from open ground. An entrance facing open ground went with significantly lower use. The BHPS adds that the entrance should not face north or north-east, to keep out cold winter winds.
• For hibernation, think warmth. The census authors’ autumn advice is to put the house on hardstanding, closer to a building, with the entrance not facing open ground. Being raised off the ground, next to a building or on hardstanding each had a somewhat positive effect.
• Not with food inside. Hedgehog Street and the BHPS both say to keep food and water out of the house, a little way off. Hedgehogs don’t usually eat and sleep in the same place. If a hedgehog moves in, the BHPS says to move feeding further away so the house doesn’t draw predators or rivals.

Gardens with a pond or good natural habitat saw lower use, possibly because those hedgehogs had better places to sleep. Pets and badgers didn’t seem to put hedgehogs off, although dogs went with lower use during hibernation.

What makes a good one

Both charities agree on most of this. Where only one source says something, we say which.

• Untreated wood. Hedgehog Street recommends untreated, durable UK softwoods such as larch, Douglas fir and red cedar, and warns that pre-treated wood can contain chromated copper arsenate (CCA) compounds “hazardous to many species”. The BHPS rules out creosote, non-water-based preservatives and paint. It allows a water-based preservative on the outside only.
• A tunnel or inner wall. If there is no tunnel entrance, Hedgehog Street says to fit an interior tunnel or dividing wall against badgers and foxes. For a ready-made house, the BHPS recommends “a solid construction with a base and a tunnel or internal baffle”. A house that is just an open-fronted box is the thing to avoid.
• A 13cm square entrance. That’s the size in Hedgehog Street’s own build instructions.
• A lid you can lift. Both charities say not to nail the roof down, so you can clean it.
• Raised slightly. Hedgehog Street’s design sits on battens so the floor is just off the ground.
• Some bedding. Put in dry leaves or pet straw. The BHPS suggests leaving a bundle of clean bedding by the entrance so the hedgehog can furnish the house itself. A heap of fallen leaves nearby does the same job.

We found no tier-1 guidance on ventilation holes for wooden houses. The only mention is that a DIY plastic-box version must have holes. We haven’t invented a spec.

Making your own

The census found hedgehogs preferred homemade houses, though Hedgehog Street says bought ones “are still a good alternative”. It can’t say whether that’s the design or the kind of person who builds one.

• Wooden box. Hedgehog Street’s free instructions use 2cm untreated timber with a 13cm entrance. The roof is held in place by battens rather than nails, and the house can be covered with polythene and then soil, turf or leaves.
• Bricks and slate. The BHPS describes an entrance tunnel of old bricks stacked securely, with a slate roof weighed down by a brick.
• The five-minute version. Turn a plastic storage box, planter or milk crate upside down. Make sure it has holes, cut a 13cm × 13cm entrance and cover it with plastic sheeting and then leaves, soil or grass cuttings (Hedgehog Street and PTES).

Hedgehog Street’s view is that the best nest of all is a natural feature, such as a log pile, compost heap or “a messy patch in a quiet undisturbed area”. A house adds to that. It doesn’t replace it.

When to put one out

None of the sources we read gives a best month. The census found houses in place for longer were used significantly more, and Hedgehog Street says hedgehogs “need time to get used to a new house”. So: as soon as you can. One put out in late October may not be found before hibernation, but leave it alone and it is better placed for next year.

Cleaning: when, and when absolutely not

Cleaning is optional. The BHPS says “some people like to clean the houses out”. If you do:

• Clean in late March or early April, after hibernation and before breeding. Hedgehog Street warns that “disturbing a mother can cause her to abandon her hoglets”.
• Check that it’s empty first. Put a light obstruction, such as a twig, across the entrance. If it hasn’t moved for several nights, the hedgehog may have left. The BHPS says to be cautious even then.
• Use hot water and a scrubbing brush, per the BHPS.
• Never clean an occupied house. The BHPS puts this in capitals.

From November until spring, leave the house completely alone. Don’t lift the lid to look. Hibernation usually starts in November, December or even January and ends around mid-March to early April. The BHPS notes that hedgehogs wake often but rarely leave the nest, that disturbance can cause these arousals, and that because they are “immobile during hibernation, they are very vulnerable to climate and disturbance”. More on that in when do hedgehogs hibernate.

To know if anyone is home, use a trail camera or the twig trick.

The honest bit

The census is a large, careful survey, but it relies on what owners reported. It shows whether houses were ever used, not how often, so its figures are a ceiling for a garden hedgehogs already visit, not a promise for yours. The design and placement advice is consistent between the two leading hedgehog charities, but the north/north-east rule and the tunnel are practical guidance, not tested findings. The biggest gain is still the gap in the fence. For food, see what to feed hedgehogs.