Use of Riparian and Upland Habitats by Small Mammals

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Abstract
Mark-recapture was conducted from 1981 through 1983 in the Cascade Range of Oregon to examine the use of riparian and upland habitats by small mammals. Both number of individuals and species richness were greater in riparian than in upland areas. Because of the occurrence of several less-commonly captured species in riparian locations, species evenness was greatest in the upland. Among Insectivora, Sorex monticolus and S. trowbridgii were captured most often on riparian sites. Among insectivores adult males weighed more in riparian zones. Three rodents (Peromyscus maniculatus, Microtus oregoni, and Zapus trinotatus) were captured more frequently in riparian habitats; two rodents (Tamias townsendii and Clethrionomys californicus) were captured more frequently in upland habitats. Among all rodents, except Z. trinotatus, adult males weighed more in riparian areas. Mustela erminea was captured more frequently in riparian sites. Eight species had greater numbers of adults in breeding condition in riparian than in upland habitats. Conversely, six species had greater numbers of juveniles in the upland. Data from several species, including T. townsendii, P. maniculatus, Z. trinotatus, and Glaucomys sabrinus, indicated that riparian habitats act as a species source and upland areas act as a dispersal sink.