ABSTRACT
Alien or introduced species are nonindigenous species that have been imported, bred, and become established in a particular region, either accidentally or deliberately. There are a variety of reasons for introduction of species to a new area, such as sport (shooting, ¢shing, and hunting), amenity or ornament, food, domestication as pets, or importation for utilitarian purposes (livestock, fur, and food). Manchester and Bullock provide examples of reasons for the introduction of selected alien species into the United Kingdom.1 Whereas most invertebrate and microbe introductions worldwide have been accidental, most vertebrate and plant introductions have been intentional. For vertebrates, there are a few exceptions to this generalization, most notably for commensal rodents and where species have been imported initially to satisfy the demands for utilitarian or ornamental purposes.
