REDUCING NON-TARGET HAZARDS OF RODENTICIDES IN FOREST SETTINGS

Authors

Wendy M. Arjo, USDA, APHIS, Wildlife Services, National Wildlife Research Center
David T. Bryson, Advanced Telemetry Systems, Isanti, MN

Document Type

Article

Date of this Version

January 2007

Comments

Published in the Proceedings of the 12th Wildlife Damage Management Conference (D.L. Nolte, W.M. Arjo, D.H. Stalman, Eds). 2007.

Abstract

Mammalian damage to forest resources is widespread and causes annual economic loss. Wildlife damage control is very important to the intensified land use practices and the economics of reforestation using seedlings. Reforestation areas provide ideal habitat for many wildlife species. However, animals negatively impact trees more severely during stand establishment than at any other time. While numerous non-lethal and lethal tools are available for large and medium-sized mammals, fewer tools are available for small mammals. The damage caused by these rodent species has in some cases warranted the use of rodenticides to control populations. Rodenticides are effective tools for reducing damage to trees by three of the more problematic rodent genera, voles (Microtus spp), pocket gophers (Thomomys spp), and recently, mountain beavers (Aplodontia rufa), when economic damage justifies this approach in a reforestation system. All of these rodents impede forest regeneration by impacting seedling establishment. Pocket gophers, mountain beavers and pine voles can also damage saplings and more mature timber through girdling of roots and stems. For the subterranean rodents, primary non-target hazards are reduced from bait placement within the burrow systems during the fall and winter. The timing of bait placement limits exposure of baits to adults and not naïve juveniles who may be more susceptible to predators. Secondary hazards are reduced in that the majority of animals that succumb to bait are recovered below ground in their nests. Above ground application for certain vole species can be more of a challenge due to costs, tools available and potential primary and secondary hazards. Wildlife species are integral to forest health, yet forest management practices can alter available habitat and influence rodent populations. When possible, managers should use rodenticides in an Integrated Pest Management approach to maximize efficacy and minimize secondary hazards.