Role of phenolics of coniferous trees as deterrents against debarking behavior of meadow voles (Microtus pennsylvanicus).

Preferences of meadow voles (Microtus pennsylvanicus) toward various coniferous species were tested under winter conditions. Cafeteria tests showed preferences for Norway spruce (Picea abies) and Norway pine (Pinus resinosa) and rejection of white pine (Pinus strobus) and white spruce (Picea glauca). When phenolic extracts of these species were prepared and added to a low 8% protein diet, food intake of voles and preferences by rank followed the same patterns. Determination of the concentration of phenolics in branch samples using the Singleton and Rossi procedure showed that Norway pines contained the smallest amount (2.15%/g dry matter) while spruces yielded the most (2.76%/g dry matter). These experiments lead us to expect high losses of Norway pine and Norway spruce in habitats harboring high vole densities.