18 - Introduced mammals in California

Summary

There are only 12 species of non-domesticated mammals now definitely living in wild populations that have been introduced by humans into the State of California. An additional three species are native to restricted ranges in the state, but have been introduced extensively beyond these ancestral distributions. Of these 15 introduced species, all but three commensal rodents were released intentionally. Six are from Europe, two are from Asia, one is from North Africa, and the rest are North American natives. There are also seven species of domesticated mammals with feral populations in California, and a few more introduced species of uncertain status. A total of 26 species are discussed in this chapter out of a total of 220 mammalian species for California as a whole.

This review does not pretend to be definitive. The situation in California is dynamic, with accidental and intentional introductions occurring regularly, and with the status of some species being unknown because of inadequate or non–existent monitoring programs. The chapter will, however, firstly summarise the history and status of the 15 introduced species of mammals; secondly, it will consider whether there are patterns of habitat use that characterise this assemblage; and thirdly, it will explore any possible insights that these mammals may suggest into the important and basic questions of what factors result in successful invasions of new areas.