EXTIRPATION OF BAILEY'S POCKET MOUSE, CHAETODIPUS BAILEYI FORNICATUS (HETEROMYIDAE: MAMMALIA), FROM ISLA MONTSERRAT, BAJA CALIFORNIA SUR, MEXICO

Seven taxa of rodents endemic to northwestern Mexico recently have been reported as extirpated: Peromyscus maniculatus cineritius, P. pembertoni, Dipodomys gravipes, Oryzomys couesi peninsularis, Neotoma anthonyi, N. bunkeri, and N. martinensis (Lawlor 1983, Mellink 1992, Smith et al. 1993, Alvarez-Castañeda 1994, Alvarez-Castañeda and CortésCalva 1996). Extirpation of these rodents may be a consequence of human activity and the introduction of nonnative species, primarily cats (Felis silvestris) that prey on the endemic rodents and Mus musculus and Rattus rattus that may compete with native species for resources (Alvarez-Castañeda 1997). We report the possible extirpation of an endemic rodent, Bailey’s pocket mouse (Chaetodipus baileyi fornicatus), from Isla Montserrat.