Voles of the genus Microtus and Clethrionomys are considered to be major mammalian pests in coniferous and deciduous tree plantations in North America. Voles may feed on bark, vascular tissues, and sometimes roots of trees, particularly during winter months when alternative food sources are limited. This damage may result in direct mortality from girdling and clipping of tree stems or reduced growth of surviving trees that have sub-lethal injuries. In terms of conservation and sustainability of temperate forests, feeding damage may limit regeneration of appropriate tree species in certain forest ecosystems, become costly to reforest these stands in time for Free Growing Status, decrease net productive forested area, and result in loss of Mean Annual Increment. Feeding damage appears to be associated with high populations of voles in early successional habitats that develop after harvesting. The problem is widespread throughout the southern and central interior of B.C. The use of diversionary food is an ecologically favourable way to reduce feeding damage by voles during those months when alternative natural foods are in short supply. A diversionary food needs to be palatable so that voles will eat it in preference to coniferous tree seedlings. However, the food must not be overly nutritious such that it enhances vole reproduction or survival. The diversionary food being utilized in this project consists of alfalfa, canola oil, and bark mulch with wax as a cohesive aggregate. The project will monitor vole populations, and test this technique to decrease mortality of trees from winter damage by voles, over a 3-year period. If trials are successful, this will result in increased plantation survival, thereby directly providing positive benefits to sustainable forest management.
Thomas P. Sullivan.
Sullivan, Thomas P., Sullivan, Drusilla S.. 2006. Use of diversionary foods to reduce seedling damage by voles. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report