The Island Fox (Urocyon littoralis) is a small fox that is native to six of the eight Channel Islands (California). It is the smallest fox species in the United States. There are six subspecies of the fox, each unique to the island it inhabits, reflecting its evolutionary history. Other names for the Island Fox include Coast Fox, Short-Tailed Fox, Island Gray Fox, Channel Islands Fox, Channel Islands Gray Fox, California Channel Island Fox and Insular Gray Fox. The Island Fox shares the Urocyon genus with the mainland Gray Fox, the fox from which it is descended. Its small size is a result of island dwarfing, a kind of allopatric speciation. Because Island Foxes are geographically isolated they have no immunity to parasites and diseases brought in from the mainland and are especially vulnerable to those domestic dogs may carry. In addition, Golden Eagle predation and human activities devastated fox numbers on several of the Channel Islands in the 1990s. Four Island Fox subspecies were federally protected as an endangered species in 2004, and efforts to rebuild fox populations and restore the ecosystems of the Channel Islands are being undertaken.