Back on topic, cats in Australia have caused the extinction of about 20 species of cute native animals and put many more on the endangered list. Morrissey, one of England's best known feline fanciers, got all upset when Australia announced plans to kill 2 million feral cats a couple of years ago.
Feral cats are responsible for similar destruction in Asian nations because few are neutered and unwanted kittens go wild.
Britain's attempt to save red squirrels in the 1970s by importing cats to prey on grey squirrels was a disastrous failure. Going further back, bringing grey squirrels over from America in the 1870s to control acorn numbers was an equally shortsighted move.
As for hedgehogs, they don't make great pets, as they invariably try to crawl under their water bowls and spill them. Though they are otherwise easy to look after and eat just about anything.