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.
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.
|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|
A fully grown hedgehog should weigh something in the region of 1000 grammes and can eat 200 grammes of food per night.