Great Basin Naturalist


Mortality of nontarget small mammals was determined after application of three black-tailed prairie dog (Cynomys ludovicianus) rodenticide treatments (prebaited zinc phosphide, prebaited strychnine, and strychnine alone) in western South Dakota. Immediate (September 1983) and long-term (September 1983 through August 1984) impacts on deer mouse (Peromyscus maniculatus) relative densities were evaluated and the three rodenticide treatments were compared for efficacy. The three treatments had no significant (α < .10) immediate impacts on deer mouse relative densities, although zinc phosphide did lower them; that impact was not, however, long term. Long-term impacts of the two strychnine treatments were variable, with an increase in deer mouse densities with the strychnine only treatment. Overall, comparisons among the three treatments indicated that zinc phosphide was more effective than either strychnine treatment in reducing deer mouse densities.