Demographics of Small Mammals Using Anthropogenic Desert Riparian Habitat in Arizona

Resource managers attempting to rehabilitate degraded desert riverine ecosystems must understand the effects of vegetation management on riparian wildlife.I used capture-recapture methods in February, June, and September 1992, and February 1993 to investigate demography of small mammals at a 4-ha site on the xerified lower Colorado River floodplain, 5 years after treatment to replace saltcedar (Tamarix ramosissima) with native woody plants.The site had become a mosaic of various vegetation types, including closed-canopy cottonwood/willow (Populus fremontii/Salix nigra), with no natural counterpart.I captured 9 of 15 native small mammal species potentially resident in local riparian habitats.Abundances of 7 of these showed a net increase over the year, although the rise was significant (P < 0.05) only for the deer mouse (Peromyscus maniculatus).Models incorporating estimates of recruitment via reproduction and survival were adequate to explain observed population dynamics, supporting the hypothesis that the site represents source habitat for most species.However, the site may have been a population sink for the deer mouse.Although not statistically analyzed, community biomass rose from 3,200 to 4,700 g/ha, reflecting contributions from the white-throated woodrat (Neotoma albigula), cactus mouse (P.eremicus), and Arizona cotton rat (Sigmodon arizonae).High biomass suggests the site has the potential to be important in local ecosystem functioning.