Great Basin Naturalist


We compared vertebrate populations between the two major islands (Paoha and Negit) in Mono Lake, California, and the adjacent mainland to further elucidate the mechanisms underlying island colonization. Deer mice (Peromyscus maniculatus) and montane voles (Microtus montanus) were captured on Paoha, but only deer mice were captured on Negit. In contrast, eight species of rodents were captured on the mainland. Overall rodent abundance on Paoha and the mainland was similar, but on Negit it was about three times greater than on Paoha or the mainland. Adult deer mice from Paoha were significantly (P < .05) smaller in most external body characteristics than mainland mice. Coyotes (Canis latrans) and one or two species of lagomorphs were observed on the islands and the mainland. No amphibians or reptiles were found on the islands; both occurred in low numbers on the mainland. Rafting and human transport are probable means of colonization for mice and voles. The occurrence of coyotes on the islands may have modified historic predator-prey relationships, and thus the population of rodents and lagomorphs.