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Consider the infamous brown rats of New York City, which have evolved longer noses and shorter upper molar tooth rows, the better to enjoy the Big Apple's colder weather and higher-quality food.

The rats really do steal the show . . . well, not quite.

It all makes for a wonderful environment for rats to thrive.

The island's isolation means that it is protected from predators such as rats, cats, dogs and foxes, and also from the human impact on the mainland.

"Sleeping through the night you'd have rats and mice and cockroaches crawling over your body," he told BBC Radio Wales Breakfast.