Deer mouse and meadow vole population and community dynamics in metal and arsenic contaminated areas at the Anaconda Smelter Site, Deer Lodge County, Montana

Abstract

I assessed demographics of resident small mammals in 1999 and 2000 on remediated and naturally vegetated sites at the Anaconda Smelter Superfund Site in Deer Lodge County, Montana. Ten frapping grids were located on remediated plots (n= 4) and natiirally vegetated plots (n=6) of varying metal and arsenic concenfrations. Markrecaptiue frapping and sample collection allowed comparisons of population and community parameters (e.g., species diversity, rodent biomass, abundance, survival, reproduction) and concenfrations of As, Cd, Pb, Cu, and Zn in tissue, soil, and stomach contents. Deer mice (Peromyscus maniculatus), followed by meadow voles (Microtus pennsylvanicus), dominated all frapping grids. Estimates of deer mouse survival, number of reproductively active aduft females, and number of non-adults on naturally vegetated grids were corrected for a covariate (number recaptured, number of adult females captured, total captured) using a common-slope analysis-of-covariance model. Canonical correlation resufts indicated significant (p<0.05) positive correlations between deer mouse population variable sets and concenfrations of COCs in soil and tissue for both years, however, partial correlations (canonical weights) for population variables varied greatly between years. Abundance, and survival were positively correlated, reproductively active females were uncorrelated (R < 0.2), and number of nonadults negatively correlated in 1999 with concentrations of COCs in soil, whereas in 2000, reproductively active females and number of nonadults were positively cortelated, abundance was negatively correlated and adult survival was uncorrelated. Canonical correlation resufts indicated a relatively strong (canonical weight = -0.53) significant (p = 0.04) negative cortelation between COCs in soil and species diversity in 1999; however, the canonical weight did not remain negative in 2000. Concenfrations of COCs in deer mice tissues were generally greater on remediated grids than naturally vegetated grids, despite lower concentrations of COCs in soil. However, deer mouse and meadow vole populations on remediated grids also do not appear to be adversely affected by COC contamination.