General Information on Our Native Wildies

Scientific name: Erinaceus europaeus

Size: Hedgehogs grow to around 25cm from nose to tail, and have a bulky body weighing around 1kg. The tail is between 2 and 3cm long

Distribution: Found throughout the UK

Months seen: April to October. Hedgehogs hibernate for the remainder of the year

Habitat: Hedgerows, grassland and gardens

Food: Beetles, slugs, snails and other invertebrates

Special features: Hedgehogs are different from every other UK mammal in that they have a coat of around 6,000 spines on their back. Although the spines are sharp, they are not barbed like the spines on a porcupine.

There can be up to 500 fleas on one hedgehog, but the fleas are a specific type which have adapted to life amongst the tough hedgehog spines. Although they sometimes get passed to dogs, cats and humans, they rarely bite. When they do, they usually drop off and go looking for another hedgehog.



Hedgehogs do their hunting at night. They have a strong sense of smell and hearing, but relatively poor eyesight. They're great to have in the garden, since they eat many of the creatures which gardeners regard as pests. They get their name from the pig-like snorting noise they make while snuffling through hedgerows. The males are called boars and the females are called sows.

Hedgehogs can swim, climb almost vertical walls, and run at speeds of up to two metres per second.

They reach sexual maturity in their second year. After emerging from their first winter in hibernation they build up their body weight, and by late April they are ready to breed. The ideal mating time would be on a warm night, usually between May and June.

Mating begins when the male finds a female on his nightly hunting trip. As he approaches her, he makes lots of pig-like snorting noises, and then he shuffles round and round her, trying to gain her attention. This can sometimes go on for hours, as the female is usually more interested in foraging for food than mating. All the male can do is snort louder, and circle closer to her.

If he is persistent enough, the female may give in and allow the male to mate with her. Mating only lasts for a minute or two, but the female must completely flatten her back before the male can mount her, otherwise he could be seriously injured on her spines. After the two separate, the male plays no further part in bringing up the family. If the mating is successful, the babies are born four weeks later.

Hedgehogs generally have two litters each year of between five and seven young. The female makes a nest just underground of dry leaves and grass. In gardens they often choose to nest under sheds. Fortunately for the mother, the hoglets are born without spines, but are covered with short white hairs which gradually turn into spines.

After one month the young are ready to leave the nest on foraging trips with their mother. After two months they are ready to leave their mother who will then start another brood.

In order to protect themselves from predators, hedgehogs have a row of muscles along the underside of their bodies which allow them to roll up into a tight ball of prickles. Unfortunately this is no defense against the motor car, and thousands of hedgehogs are killed on UK roads every year.

In Britain the hedgehog hibernates between October and April when the weather is cold. They shelter somewhere warm and dry, like a pile of leaves or logs. Always check piles of garden waste before starting a bonfire, there may be a hedgehog in there!

Hedgehog Lifestyle


Diet

Hedgehogs are insectivores, i.e. their diet mostly consists of insects. Although there may be some differences due to availability, in general their diet is similar regardless of species or location. British and German research has found the following foods in the diet of European hedgehogs:

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A hedgehog will spend almost all of the hours between dusk and dawn searching for food. In this time it will travel around one kilometre, usually ending its search where it started - at its nest. It appears that the animal knows exactly where it is going and will regularly visit the same place if it finds a plentiful food supply there.

Sleeping
During the summer, hedgehogs spend the day sleeping in a light, flimsy nest constructed from grass and leaves. They will have a number of such nests, and often sleep in the same one before returning to a nest they have used previously. A nest may be slept in at different times by several hedgehogs; they don't seem to mind who originally built it. When the weather is warm, a hedgehog may not bother to build a nest at all but will simply lie under a pile of leaves or among long grass.

The main reason for the hedgehog being nocturnal is that its food is mostly nocturnal too. The creatures that it eats are small invertebrates that are active at night to avoid other predators, or those that must keep out of the heat of the sun to avoid water loss.

Hibernation
Like all animals, hedgehogs need energy to survive. In their case, it comes from beetles, worms slugs and other small creatures that they consume each night. In summer, these invertebrates are plentiful, but as the weather gets colder its food becomes scarcer. The hedgehog is then in danger of using up more energy in finding food than it gains from eating it. Hedgehogs are more prone to this problem than other small mammals as they lack the insulation provided by a fur coat.

Hibernation is not always a part of the hedgehog's life cycle. European hedgehogs found in New Zealand generally do not hibernate, and if they do it is only for a few weeks. In contrast, Scandanavian hedgehogs have an extended hibernation period as winters in the region are longer. Hedgehogs will only hibernate for the minimum necessary period as the process is hazardous. Nevertheless, hibernation is a valuable strategy that gives the hedgehog a chance to live through conditions through which it would have no chance of surviving.

The hedgehog's winter nest, or hibernaculum, is made of grass and especially of leaves, which are weatherproof and long-lasting. The hedgehog brings leaves to the nesting site in its mouth, a few at a time. It makes a pile, adding new leaves to the centre - and these are held in place by the surrounding twigs, brambles etc. It then burrows inside and turns round and round, packing the leaves flat and ending up with walls up to 10 centimetres thick. The hedgehog will make a new nest in this way every year.

The hedgehog's hibernation is more complex than just a lengthy sleep. It involves lowering the energy consumption of the animal by lowering the metabolic rate, slowing down the pumping of blood and lowering its breathing rate so that it may not take a breath for several minutes - making it appear dead. The only observable difference being that it will bristle its spines when touched. The hedgehog's body temperature can be lowered from the usual 35ºC to as low as 4ºC and the heart will only beat around 20 beats per minute. These reductions mean that the energy required to keep it alive is around one fiftieth of its normal energy expenditure. These reductions mean that the hedgehog requires very little energy, but it must survive the whole winter on its fat reserves. It is therefore vitally important that the hedgehog eats well before the winter season - building its weight up to at least 600g. It a hedgehog's weight is much below this threshold, it will probably not survive the freezing winter.

Hibernation is not continuous - a hedgehog usually wakes for a short time every seven to eleven days. Its body temperature returns to normal, and it usually remains alert inside its nest, although sometimes it may leave the nest and be active for several days or even move to another nest. It is unknown why the hedgehog might do this as there is no apparent benefit. Arousals are mostly spontaneous but can also be due to outside factors such as flooding, warm weather or disturbance of the nest by humans or animals.

By the beginning of March, the hedgehog's fat reserves which have sustained them through the winter will be almost exhausted. The first mild nights of March see the emergence of the first hungry hedgehogs. During the inter they will have lost a substantial art of their body weight and they must quickly replace it. If cold weather sets in again, they will return to their winter nests. By mid-April all hedgehogs should be out busily feeding on the insects that are once again abundant in gardens and the countryside.

Hedgehog Facts
A frequent visitor to our gardens, the hedgehog travels widely about it's suburban home. As their name suggests though these familiar mammals prefer the comfort of the hedgerow. Despite their bumbling appearance hedgehogs can move speedily and defend themselves from would be assailants with a coat of over five thousand spines.

A familiar defensive action of these prickly customers is to curl themselves up into a ball when attacked. Two pairs of muscles pull skin over head and bottom, while a further ring of muscle circles the spiny coat and contracts to enclose feet, head and tail. The hedgehog is probably around ten million years old and has adapted to use man-made hedges as homes and motorways connecting food supplies. A shrewd survivor, the hedgehog keeps most of it's life a secret, only venturing out after dark. This being a strategy used to exploit a huge range of insect life that becomes active at night.

A foraging hedgehog may travel 3 km within a home range of 24 ha in a single evening. They most certainly are not the sluggish movers that they are portrayed as. Indeed, climbing in the lower branches of a hedge, to feed on caterpillars and other leaf insects, is not uncommon. Hearing and sight are reasonably well developed, but hedgehogs have an excellent sense of smell. Probing the air and leaf litter with a long snout, the hedgehog sniffs out spiders, slugs and worms. Even beetles buried a few inches in the soil are not safe! Hedgehogs also eat fresh carrion and occasionally raid bird nests for eggs and chicks, whilst eating almost no plant material at all.

Come spring, males and females or boars and sows, find each other for mating by a combination of smell and good fortune. The following courtship dance can continue for several hours, but after mating is complete the boar plays no further part in raising the young. The female begins to eat a great amount of food and builds a large well constructed nest, usually located deep in the thickest part of a hedge. After around 30 days four or five helpless blind young are born. In two weeks their eyes are open and a recognizable coat of brown spines appears. At one month old they are suckling from their mother, but occasionally take solid food by themselves. The milk of the mother contains vital antibodies which transfer immunity from infection to the young. In 2-3 months the young must more than double their body weight to prepare for their first winter hibernation.

Hedgehogs hibernate over winter because their food supply, insects, becomes very scarce. They build a special hibernation nest called a hibernaculum, keeping the animal frost free and dry throughout the severest winter. Unfortunately the machine trimmed hedges of today do not provide the secure nesting sites that the traditional cut and laid hedgerows of the past did. Infact hedgehog populations may be limited at present by the lack of suitable hibernaculum sites rather than an inadequate food supply. Having lost as much as half it's body weight over winter, breathing every six seconds with a heart beat one tenth the normal rate, the hedgehog finally emerges to gorge on insects in readiness for the coming year.

Hedgehog Weights
Below is a graph showing the approximate weights for a healthy hedgehog. This is intended as a guide only, so do not worry if your little hedgehog does not conform to the graph.

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Here are the figures that the graph was taken from.
A new born baby weighs about 8 to 25 grammes
After 7 days it should weigh 25 to 60 grammes
After 2 weeks it should weigh 60 to 85 grammes
After 3 weeks it should weigh 85 to 130 grammes
After 4 weeks it should weigh 130 to 200 grammes
At 5/6 weeks it should weigh 200 to 300 grammes

We release hedgehogs in the Summer at 500 grammes and in the Autumn 600 grammes.
A fully grown hedgehog should weigh something in the region of 1000 grammes and can eat 200 grammes of food per night.

Hibernation in Hedgehogs
Most people think that hedgehogs sleep during hibernation. But, actually, for the hedgehog, hibernation is not just about sleeping. It is basically a resting time and during this period, it conserves its energy. The body temperature of the hedgehog drops dramatically during this time, which helps it to survive the winter. Read on to know more about hibernation in hedgehog.
Ever encountered a ball of spines? The best bet would be to stay calm, because it is the cute little hedgehog. One can be assured that the hedgehog will not attack unless it senses danger. Hedgehogs are spiny mammals from the subfamily Erinaceinae. There are 16 species of hedgehogs across 5 genera; they are found in Europe, Asia, Africa and New Zealand. They are nocturnal mammals which feed on invertebrates, and are prominently recognized by their spines. However, their spines are not poisonous.

Hibernation in Hedgehogs: Explained

Hedgehogs maintain a nearly constant body temperature (35 degrees centigrade) in summer. But what happens when the temperature decreases? Well, hedgehogs are smart enough to survive the cold weather. They have a fantastic ability of keeping their body temperature constant by upping the metabolic rate to generate heat.

Hedgehogs undergo thermoregulation when they are hibernating or when they are about to go in hibernation. Hibernation is one of the major activities of hedgehogs. With the arrival of winter, hedgehogs tune their body in such a way that their body temperature is around +5 to +6 degree centigrade. This is because, in winter the food becomes scarce and they cannot maintain the summer body temperature of 35 degree centigrade.

Hedgehogs are so amazingly in sync with nature that during hibernation, they use their stored quota of fat to make it through the cold weather. They use this energy minimally - just to keep their vital functions going. They create their home or habitat for hibernating, called 'hibernacula'. Or if it is a pet, which is very common in the USA or the UK, the owner can make a home for his or her cute little 'hedgie', as it is nicknamed. Hedgehogs don't go into hibernation before they gain the sufficient weight. The minimum weight required for a young hedgehog to hibernate in the wild is 500-700 grams. In addition to that, there is a sex specification in hedgehogs, males go first into hibernation and then the females. The duration of hibernation could range from 3 to 5 months.

The common places that hedgehogs use to hibernate are timber buildings, under piles of wood or leaves, or in compost heaps. However, if there is enough food, and the climate is sufficiently warm, they may not even hibernate. But it is important that hedgehogs in captivity should not be allowed to hibernate, as it could lead to a few problems. Hibernation in hedgehog is triggered by various conditions.

Factors Influencing Hibernation in Hedgehogs

Low and Sudden Dip in Temperature: A hibernation can be triggered by a temperature too low for hedgehogs. Also, if there is a sudden dip in temperature, they go into hibernation.

Inconsistency in Day-night Cycle: In case of inconsistency in the amount of light and dark, hedgehogs enter into hibernation. If the hedgehog is domesticated, and is forced to awake at erratic and different times of the day, there is a possibility that the hedgehog will go into hibernation. Hedgehogs can tell it is winter by shorter days and longer nights and they start adjusting their biological clock accordingly.

Illness: Another factor which can lead the hedgehog to hibernation is illness. During an illness, hedgehogs, rather than wasting their energy in movement, lower their metabolism to fight infection. If your pet hedgehog is ill, make sure that it is warm enough and take it to a veterinary doctor.

Age Factor: As the hedgehog grows older, it is unable to regulate its body temperature on its own. A lifespan of a larger species of hedgehog is 4 to 7 years in the wild. Smaller species in captivity have a lifespan of 4 to 7 years. However, the lifespan is just 2 to 4 years in the wild. For example, a hedgehog who is 6 years old, intends to hibernate at 72 degree Fahrenheit, while it is ready for hibernating at 70 degree Fahrenheit at a younger age.

Hibernation in hedgehogs also varies according to their species, sex and age. There are also stages when they arouse during hibernation. These are the stages when they move around a bit to hunt for food and reset their metabolism. These spiny animals definitely know how to conserve their energy.