Mating

Hedgehogs don't reach sexual maturity until the year after they were born. After emerging from hibernation they feed to build up their body weight, so it is at least late April of their second calendar year before they are ready to breed. A warm night, some time between May and September, but mainly in May and June, is a hedgehog's ideal mating time.

The ritual seems more like a fight as it is an extremely noisy event. The courtship, or 'pre-mating display', is initiated by the male when he comes across a solitary female on his nightly wanderings. He approaches her, snuffling and snorting, and circles closely round and round, trying to claim her attention. The female shows no interest; she twitches violently and repeatedly turns away from him. The male persists and circles closer, snorting louder and louder, sometimes for hours.

Often a second male will approach, attracted by the noise, but the intruder's presence is not tolerated, and the male inserts his muzzle underneath him and pushes him out of the way. The female, totally unconcerned, may wander off. A high proportion of attempted hedgehog matings fail due to the female's lack of interest.

Ultimately, however, the female may become receptive and allow the male to mount her. Mating may only last a minute or two, and then the pair separate. The male plays no further part in bringing up the family, and if the hedgehogs ever meet again, it is probably only out of chance.

Unless the female places herself in the correct position, mating will be impossible. She must lie with her hind legs spread out, belly pressed flat to the ground and nose pointing upwards. The formerly aggressive spines must be laid flat: the skin of a male hedgehog's belly is thin, and he could be badly injured. He mates with her from behind, gripping the spines with his teeth.

Hedgehog reproduction is not very efficient. The female often mates several times before becoming pregnant, and quite a few females may reach the end of the season without conceiving.

Birth

Baby hedgehogs are born approximately four and a half weeks after becoming pregnant. Although the timing is variable (compared with other mammals), the births are mostly in June and July. The variation can be explained by cold periods in early spring can cause the female to return to hibernation for a while. One theory proposes that during this period the development of her embryos could be temporarily slowed down and the birth of her babies slightly delayed. It is not uncommon for mothers who either rear early litters or lose their first family to conceive again - but these second litters may be born as late as September, and so have little chance of surviving the winter.

The babies are born into a nest similar to the one in which the mother hibernates in, except for being larger. It is made mostly of leaves and grass, but may contain anything that the hedgehog may drag back to the site. The nest doesn't include any special lining material, but by treading and turning around the mother produces a soft, comfortable interior. If the nest is disturbed soon after the birth, the mother will either abandon them, or sometimes will eat them. When they are older she may react by transferring them to another nest.

Growth

At birth:	At birth, the baby is pale pink with its spines still beneath the skin, looking like pimples. Its eyes are closed. Within hours the spines begin to appear through the skin. The first one are white. The baby appears to have a parting along the centre of its back, which gradually disappears as the animal grows.
One week:	After about a week, brown spines begin to appear among the white ones and gradually replace them.
Two weeks:	At two weeks the baby's eyes open and fur begins to grow, obscuring the flesh of its underbelly, which starts to darken from its original pink.
Two weeks:	At two weeks the baby's eyes open and fur begins to grow, obscuring the flesh of its underbelly, which starts to darken from its original pink.
Three Weeks:	The babies are weaned from about three weeks onwards. Over the next four months, or so, the milk teeth are lost and adult teeth appear.
Four weeks:	At four weeks the babies are taken on foraging expeditions by their mother.
Five to Six Weeks:	At the age of five to six weeks, the babies begin to leave the nest and fend for themselves. By this time they are about ten times their birth weight and will continue feeding until winter.

Baby hedgehogs grow very quickly for the first month of their life. When they leave their nest, their growth slows as they have to feed themselves. Unlike most animals, the hedgehog does not stop growing once it reaches maturity, but will very slowly continue to get bigger throughout its life.

The only easy way to determine a hedgehog's age is by its size. The above chart is only helpful with young hedgehogs and is only a rough guide. A small but fully formed hedgehog found in autumn is likely to be only a few months old approaching its first winter. By the time it enters its second calendar year, it will look like any other adult hedgehog.

Half of hedgehog babies die during their first year, and only about one percent of them live for more than five years. However those that do survive can live for up to 8 years in the wild.