RODENT COMMUNITIES IN NATIVE AND EXOTIC RIPARIAN VEGETATION IN THE MIDDLE RIO-GRANDE VALLEY OF CENTRAL NEW-MEXICO

Rodent communities were monitored in two native cottonwood (Populus de ltoides spp. wislizenii) and two exotic saltcedar (Tamarix ramosissima ) riparian forest sites in the Middle Rio Grande Valley of central New Mexico. Species richness was greater in saltcedar, due to the additio n of some species typically associated with dry upland or grassland co nditions, which probably reflects proximity to source habitats. The pr edominant species in both vegetation types was Peromyscus leucopus, fo r which abundance estimates, reproductive data, and sex ratios did not differ between vegetation types. June and August abundances of P. leu copus at saltcedar sites were positively correlated with precipitation the previous winter, which suggests that use of saltcedar may vary wi th short-term weather conditions.