WINTER USE OF GLYPHOSATE-TREATED CLEARCUTS BY MOOSE IN MAINE

Aerial treatment of naturally regenerating clearcuts with the herbicid e glyphosate initially reduces the availability of deciduous browse, b ut may subsequently improve bedding cover for moose (Alces alces). How ever, the potential effects of these vegetative changes on use of clea rcuts by moose has received little study. We studied effects of glypho sate treatment of clearcuts in Maine on (1) use of clearcuts by moose and (2) conifer cover during 2 periods, 1-2 and 7-11 years posttreatme nt. We made counts of moose tracks, beds, and pellet groups on transec ts in treated and untreated clearcuts in January-March 1992 and 1993 a nd measured conifer densities in January-March 1991-93. At 1 and 2 yea rs posttreatment, tracks of foraging moose were 57 and 75% less abunda nt on treated than untreated clearcuts (P = 0.013). Counts of moose be ds, total tracks, and pellet groups exhibited similar patterns as trac ks of foraging moose but did not differ (P > 0.1) between treatments. At 7-11 years posttreatment, tracks of foraging moose (P = 0.05) and m oose beds (P = 0.06) were greater on treated than untreated clearcuts. Conifer densities at 1-2 years posttreatment were not affected (P > 0 .1) by treatment, but conifers 2.0-2.9 m tall were 2 times more abunda nt (P < 0.1) on treated than untreated clearcuts at 7-11 years posttre atment. Less foraging activity at 1-2 years posttreatment appeared to be the result of reduced browse availability because conifer cover for bedding was similar on treated and untreated clearcuts. We hypothesiz ed that greater counts of tracks of foraging moose on older treated cl earcuts was due to increased foraging activity on sites with more abun dant conifer cover.