The distribution and abundance of rodents was studied on 6 eucalyptus agroforestry sites and on S agricultural types in the San Joaquin Valley from June 1987 through May 1989. Deer mice (Peromyscus moniculanus) were the most abundant rodent on S of the 6 study sites. Based on 14,250 trapnights, deer mice comprised 82% of the rodent captures in agroforestry plantations; California voles (Microtus californicus), 8%; house mice (Mus musculus), 7%; and western harvest mice (Reithrodotornys megalotis), 3%. In 9,019 trapnights in agricultural habitats (alfalfa, cotton, tomatoes, sugar beets, and fallow lands), deer mice comprised 77% of the captures; house mice, 22%, and California voles, 1%. Rodent communities within the plantations had denser populations and smaller home ranges than those rodent populations in the agricultural habitats. Rodent density was inversely related to plantation age. Densities of Peromyscus in the plantations ranged from 22 to 282 animals per ha, depending on the site being sampled, during the 8 quarters of the study. Estimated home ranges in agricultural habitats were more than 4 times larger than in the tree farms. Capture distribution of rodents varied significantly between study periods and most during periods of population decline.
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