18. The perfect hunter.

Here in Norway, a rather original threat to the environment has revealed itself - the domestic cat. There's around half a million of them( to a human population of 4.7 million), and, though domesticated, they're still passionate and terrific hunters. They kill around five million birds a year, and now scientists also fear for rare amphibians and snakes. Basically, any animal smaller than itself, as with most predators, is considered prey.

But, before the cat-hunt starts, I hope they try to figure out just how many rats our tiny tigers kill each year. Somebody's going to have to take over their job.