RESPONSE OF CAPTIVE SNOWSHOE HARES TO THIRAM-TREATED CONIFERS

The retention time required for snowshoe hares (Lepus americanus) to m aintain a feeding aversion to thiram has important forestry management implications. Thus, we investigated the forage preferences of captive hares for thiram-treated and untreated white spruce (Picea glauca) wi th animals having either previous exposure or no exposure to treated t wigs. Thiram reduced the mean consumption of spruce twigs by previousl y exposed and naive hares 9-fold and 5-fold, respectively. Previously exposed hares had an untreated spruce intake 2-fold that of naive hare s. The decreased consumption of untreated twigs by naive hares in comp arison to previously exposed hares suggested that naive animals had de veloped a generalized aversion to spruce twigs or that previously expo sed hares were more adept at differentiating treatment types. The cons umption of similar amounts of white spruce treated with thiram by both types of experience groups indicated that a learned food aversion had not been established with previously exposed animals or that extincti on of the aversion had occurred. In the wild, even if hares acquired a n aversion for treated conifers during autumn through spring, extincti on of the aversion would likely occur over the summer months. Conseque ntly, this would not only necessitate the reapplication of thiram more frequently than feasible for foresters, but would also require a reco nditioning period for hares during which conifers would be susceptible to browsing damage.