A Case of White-Tailed Deer Controlling the Woody Vegetation in a Power Line Right-of-Way Located in a Winter Yard

Abstract

The clearing and subsequent vegetation control in power line rights-of-way located in white-tailed deer (Odocoileus virginianus) winter yards in Eastern Canada and the Northeast United States remain significant environmental issues. The Rigaud white-tailed deer (Odocoileus virginianus) yard is located approximately 100 km west of Montreal, Quebec. The yard is bisected in a north-south axis by a 120 kV transmission power line built in 1972. The power line collapsed during a major ice storm in January 1998 and was rebuilt in the summer and fall 1998. In the summer of 1998, a mechanical brush cutting treatment was completed and the vegetation was further damaged by construction activities. By October 2002, numerous woody stems were taller than 2 m. The vegetation was then treated with handheld manual brush cutters. During the winter 2003, the right-of-way provided very little browse, but on several occasions, deer browsing was observed in the right-of-way for long periods. It formulated the hypothesis that deer browsing pressure controlled the residual woody vegetation in the right-of-way. The April 2003 and 2004 browse surveys targeted the stems of three species sought by deer: red-osier dogwood (Cornus stolonifera), American ash (Fraxinus americana) and willows (Salix spp.). Sampling over 200 stems of each species each spring was done. All these residual stems were short and most were missed during the October 2002 treatment. Browsing rates on C. stolonifera, Salix spp. and F. americana were, respectively, 97.3%, 97.3% and 84.9% in 2003, and 96.3%, 97.3% and 89.2% in 2004. These very high-browsing rates indicate that when stems are short and deer density is high, deer can exert a certain control of the woody vegetation in a right-of-way in a deeryard, at least during the first winters following a vegetation control treatment.