WINTER UTILIZATION BY MOOSE OF GLYPHOSATE-TREATED CUTOVERS

Abstract

Glyphosate (N-(phosphonomethyl) glycine) is an important silvicultural tool used in the boreal forest. This study was undertaken to determine if the use of this herbicide for controlling competing shrubs in plantations is significantly reducing forage resources and subsequent overwinter utilization by moose (Alces alces) up to 3 years post-spray. Observations were carried out on 4 glyphosate-treated and control paired cutovers near Thunder Bay, Ontario.

Moose presence and feeding activity throughout winter, as measured by periodic, systematic aerial track counts, indicated that the numbers of overwinter moose tracks were not significantly different (P > 0.05) after 0 and 1 growing seasons post-spray, but they indicated a preference for the non-sprayed control areas (P < 0.05) at 2 and 3 growing seasons post-spray. The number of moose track aggregates were similar in all control and treated cutovers (P > 0.05), prior to the first growing season post-spray, but were more numerous (P < 0.05) on control portions, 1, 2, and 3 growing seasons after treatment. Available moose browse, on control areas, was four times greater, and browse utilized was 32 times greater, than that in treated areas (P < 0.05) after 1 growing season post-spray. Estimated winter moose presence, calculated from pellet counts, was almost two times greater on untreated than treated areas after 1 growing season (P < 0.05) and similar at 2 growing seasons post-spray.

The effect of major habitat changes brought about by forestry activities on the total moose population is discussed. It is difficult in a 3-year study to formulate conclusions based on results that take many more years to manifest themselves. Further research is recommended to determine the long term impact of glyphosate application on wildlife habitat.