Introduction

What is a Hedgehog and what does it look like?

Generally speaking, the hegdehog is a small spiney mammal (indeed it is Britain's only spiney mammal) which belongs to the group Erinaceus europaeus. It has spines covering most of the upper part of the body, walks on four legs, is a nocturnal feeder and eats insects. It is this last fact which makes this mammal one of the most welcome wild animals in Britain today. It's ability to eat it's bodyweight in insects in one night (many of the insects that are considered harmfull to plants) means that a hedgehog can help the gardener to keep pests down to a managable level completely naturally. 

What are the spines used for?

The spines on the back of a hedgehog are actually modified hairs, there can be five thousand spines on an average hegdehog. Each spine growing to about an inch long and lasting 12 months before falling out and being replaced by a new spine. Muscles under the skin allow the spines to be erected for protection, since the lower part of the hedgehog is covered in soft fur and is thus vunerable to attack if it can be turned over.  

To get around this problem, the hedgehog's skeleton is shaped with a long spine, which allows it to curl up into a ball if threatened. More muscles around the edge of the spines allow the spines to be drawn together, surrounding the head and legs.
Thus it can turn itself into a ball of spines which should prove a positive defence against unwanted interest from a predator.

The picture on the right shows a curled up hedgehog turned over on it's back to show the completeness of it's defence.

Are they all brown?

The colours of hedgehogs are generally as the picture on the right, a brown colour. However, hedgehog colours can also range from white (such as the blond hedgehogs which have thrived in Alderney, in the channel islands) through to the very rare black variety. Albino and sometimes spineless varieties are found but invairably these are already dead due to their colours proving no camoflage during the night from their predators.

What's under the skin?

The skeleton of a hedgehog is very basic and shows the length of time that the hedgehog has been with us. It is estimated that the hedgehog has been evolving for over ten million years, making it one of the oldest species of mammal. It has 36 teeth which are suited to it's diet. However, these teeth are incapable of delivering a serious bite to humans. Their long legs and short tail are mostly hidden underneath their spines and the hair along the sides of the body. The feet have five toes which have strong claws growing from them.

How big do they get?

Size can vary in a hedgehog depending on age, sex and time of year. Below are some typical weights:

As you can see, the time of year is important to the size of the hedgehog. This is because the hedgehog hibernates (sleeps) through the wintertime and must rely on stored fats in the body to see it through to the spring. Indeed, a hedgehog must weigh at least 450g to be able to survive the winter sleep.

Why do hedgehogs hibernate?

Hedgehogs hibernate to conserve their energy since the cold months of the year mean that food becomes scarce. The hedgehog simply tries to bypass that time of year completely. It does mean, however, that they need to have stored up enough body fats to take then through the winter.