The invasion of the hedgehogs.

In 2002 hedgehogs were introduced onto a small island off the west coast of Scotland. Hedgehogs had never lived there before and nobody thought they would have much impact on the island. However, they were wrong. In months, the hedgehogs had grown enormously in number. Now there are thousands of them and they have completely changed the balance of nature on the island. They eat almost anything, including birds eggs and some species of birds have almost disappeared. Originally people thought that the problem would be confined to only one island, but when the tide is low the hedgehogs turn into tourists and cross the sand to visit other islands. The final result could be a whole group of Scottish islands infested by hedgehogs!