Alternative conifer release treatments affect small mammals in northwestern Ontario

Density changes of small mammals responding to different conifer release treatments (motor-manual [brush saw] cutting; mechanical [Silvana Selective] cutting; helicopter-applied herbicides [Release® (a.i. triclopyr), Vision® (a.i. glyphosate)]; controls [no treatment] were quantified. A total of 4,851 small mammals were captured and released during the three-year study. The most commonly captured (81% of total) species were: shrews (masked [Sorex cinereus Kerr], pygmy [S. hoyi Baird], arctic S. arcticus Kerr]), southern red-backed voles (Clethrionomys gapperi Vigors), and deer mice (Peromyscus maniculatus Wagner). Northern short-tailed shrews (Blarina brevicauda Say), eastern (Tamias striants L.) and least (T. minimus Bachman) chipmunks, meadow voles (Microtus pennsylvanicus Ord), ermine (Mustela erminea L.), and meadow jumping mice (Zapus hudsonius Zimm.) were common. Shrew (masked, pygmy, arctic, short-tailed) densities were statistically unaffected by these treatments. Red-backed vole densities were highest on control plots during the first post-treatment growing season, and highest on control and Vision® plots during the second post-treatment growing season. During the first two growing seasons after treatment, deer mouse densities were highest on Silvana Selective plots; eastern chipmunk densities were highest on control, Vision® and Silvana Selective plots; least chipmunk densities were highest on Vision® and Release® plots; and meadow vole densities were highest on Release® plots. Small mammal responses to the alternative conifer release treatments examined were species specific one and two-growing seasons post-treatment, but similar to responses common to the standard (Vision® herbicide) conifer release treatment. Key words: conifer release, Fallingsnow Ecosystem Project, glyphosate, herbicides, Release®, small mammals, spruce plantation, triclopyr, vegetation management alternatives, Vision®, wildlife habitat