Species: Hystrix brachyuran
Origin: South Asia
Where: Pine Valley Wildlife Park, Devon, U.K.
Why: Lovers on the run? A single pair of Himalayan porcupines escaped from a wildlife park in England and reared a litter. Their little family grew in size, attacking crops and stripping bark from trees. All the animals were caught with traps by 1979.
Species: Macropus rufogriseus
When: Beginning in 1900
Why: Escaped from zoos. Red-necked wallabies do surprisingly well in the cool and misty British Isles. Small groups live in Scotland, the Isle of Man, and England.
Species: Papio Anubis
Origin: Central Africa
Where: Cadiz, Spain
Why: Escaped from an abandoned wildlife park. Originally a group of 60, the free-ranging baboons dwindled to 20 by 1998. The government captured most remaining animals and put them in a zoo in 2001.
Species: Meriones unguiculatus
Why: The blond Barbie of rodents, the Mongolian gerbil was a popular house pet in Paris of the late 19th century. Small colonies live in the U.K., where it was introduced from the U.S. in 1964. The first recorded colony in the U.K was discovered in Yorkshire in 1971.