This authoritative and eminently readable book relates how the alien vertebrate animals now living in the wild in Britain and Ireland were introduced and naturalized, their status and distribution, and their impact on the local environment. The core of the book describes animals that have been imported deliberately or accidentally and have established populations in the wild, among them the Red-necked Wallaby, Monk Parakeet and African Clawed Toad. There are also sections on feral domesticated species such as feral cats, goats and Reindeer, ephemeral species such as the Canadian Beaver and Mongolian Gerbil, and reintroduced species like the now-thriving Red Kite. Distribution maps show the locations of most of the featured species, and full-colour photographs reveal their amazing diversity.