Hedgehog

Typical of a nocturnal species, their eyesight is poor but they have good hearing and a very well-developed sense of smell.

Hedgehogs have been known to live for seven years, but a lifespan of two to three is more typical.

Hedgehogs are solitary, with no evidence of territoriality. They move around a lot each night in their search for food, males covering a slightly bigger area than females. You can see some detailed radio tracked hedgehog movements here. This really emphasises the importance of providing routes so that they can move around and access sufficient food.

Hedgehogs are carnivores eating all kinds of invertebrates (especially beetles and earthworms, but also caterpillars, slugs, snails, centipedes and millipedes), as well as amphibians, birds' eggs and anything else they can catch. In gardens this diet should make them the gardener’s friend but it has also put them at risk from pesticides and slug pellets.

Spines

An adult hedgehog’s back is covered in sharp spines, some 5,000 - 7,000 of them each around 2-3cm in length. The spines are made of keratin; the same material as human hair and nails. Hedgehogs shed their spines over time, with new ones growing in to replace them, just like our hair.

Baby hedgehogs, or hoglets, are born with their spines concealed beneath their skin and shortly after birth, their spines ‘come out’.

A hedgehog’s spines are its main mode of defence against predators. When threatened, the hedgehog will curl up into a tight, spiky ball. The hedgehog has a muscle around its body which contracts to allow the hedgehog to curl up, a bit like a draw-string bag. This is sufficient to deter most cats and dogs which soon learn that trying to grab a hedgehog is a painful experience.

The spines are not enough to deter a badger which is the main predator of hedgehogs. A recent detailed study in Cambridge revealed an east / west split in the city with sightings of hedgehogs largely confined to the east of the urban area, the west of the city has several badger setts but few hedgehogs.

Nesting

Hedgehogs make nests for three reasons: to spend the day, to hibernate during the coldest months of winter, and for breeding. The day nest is quickly created from dry leaves, moss and grass and new ones are made frequently as the adults forage around their home range. The winter nest or ‘hibernaculum’ is more substantial as the hedgehog will spend probably two-three months in it. The sow makes the breeding nest which must be well hidden and robust enough to hold the growing family for about a month.

Our gardens are an increasingly important habitat, and here they will move into custom-made ‘hedgehog houses’, though they are equally happy living under a shed or decking. Leaving corners of your garden untidy with perhaps a log pile or leaf pile will help hedgehogs looking to build a nest.

Life cycle

The breeding season runs from mid-May to late September, but most births occur June/July. Hedgehogs have a semi-aggressive courtship, involving the boar circling and head-butting the sow with one or both hissing and snorting. This circling can go on for an hour or more and on most occasions does not lead to mating. If another boar arrives the males will tussle and the sow may just wander off. You can see video clips here.

Sows can produce two litters in a year in favourable conditions. Pregnancy lasts just over a month and typically a litter has 4 or 5 young. The young leave the nest to forage with their mother at 4 or 5 weeks old (late-July); are weaned by 6 to 8 weeks and independent by 4 months. The father plays no part. Late litters (“autumn orphans”) may have insufficient time to fatten up prior to hibernation.

Hedgehogs hibernate over winter, from November or December to about March – but this depends on how cold the winter is. This allows hedgehogs to survive while their insect food prey is in short supply. During hibernation hedgehogs are not really asleep, instead they drop their body temperature to match their surroundings and enter a state of torpor. This allows them to save a lot of energy but slows down all other bodily functions making normal activity impossible. Hedgehogs do occasionally awake from hibernation during periods of milder weather in order to forage for food.

Have you got one visiting your garden?

You may not have seen them BUT they might be in your garden.

Things to check for:

• Listening for piggy snuffling noises and rustling of dead leaves after dark.

• You might also hear a hedgehog eating – they are really noisy eaters!

• Keep an eye out for hedgehog poo on your lawn - dark pellets about an inch long or the size of your little finger, bullet-shaped, shiny black containing glittering insect remains.

• Looking for tunnels in the undergrowth of your borders or narrow paths across a patch of long grass which you have left for ‘No Mow May’.

You can also check on this interactive map to see who has recorded hedgehogs in the village – there might be someone near you: https://bighedgehogmap.org/ If you find that you have hedgehogs then you can add to the map.

How you can help

Histon and Impington has its own group dedicated to improving the prospects for hedgehogs within the villages. HI Hedgehog Champions want to connect gardens by encouraging householders to make hedgehog holes in boundary fences creating a village hedgehog superhighway.  The aim is to have a Street Champion for every road in the two villages.  Street Champions help and encourage their neighbours to join their garden to the highway.

If you are interested in becoming a Street Champion, helping to bring awareness of local hedgehog needs to those in our village or just to find out more, contact hihedgehogs@gmail.com.

If you are thinking of putting food out for hedgehogs please remember these important rules.

Don’ts

• Never put out milk (hedgehogs are lactose intolerant)

• Certain bird foods are bad for hedgehogs in any quantity (and hedgehogs are greedy) so avoid: peanuts, sunflower hearts, dried mealworms

You can contact the HI Hedgehog Champions for more advice.