The effects of prescribed burning on deer and elk habitat parameters in Montana's Missouri River Breaks

Abstract

Fire suppression has been practiced along the Missouri River Breaks for decades and has led to a series of resource issues. Among these issues was a build up of dangerous fuel loads and restricted foraging areas for livestock and big game. Because the Missouri Breaks are an important wintering area for mule deer ((Odocoileus hemionus hemionus Rafinesque) and elk (Cervus elaphus nelsoni Bailey), the Bureau of Land Management (BLM) wanted to know how a series of prescribed burns in late May and early June of 2002 would affect habitat. The prescribed burns left a mosaic of unburned, scorched, and heavily burned landscape across the study site. There was concern that the reductions in hiding and thermal cover and decreased browse availability would have adverse impacts on the mule deer and elk populations. To evaluate the possible impacts of the prescribed fire on deer and elk populations use of unburned, scorched and heavily burned areas were compared using pellet group counts and winter browsing pressures. Thermal and hiding cover measurements were taken to quantify fire intensity effects on cover loss. Forb and grass rejuvenation was monitored one and two years after the burn to measure the impacts to the forage base. Thermal cover did not differ significantly (P>0.10) between unburned, scorched, and heavily burned areas. Scorched and heavily burned areas had significantly less (P<0.10) hiding cover than unburned areas. While grass did not differ significantly among the treatments, forbs were greater in the second year after the burn in scorched and heavily burned areas. Pellet groups counts indicate that mule deer used all burn intensities and showed no indication of preference or avoidance of various cover levels or forage availability. Elk use of the study site was too minimal to analyze. There was no significant difference (P>0.10) between browsing pressures in meadows of burned and unburned areas, suggesting that deer did not select browsing areas based on adjacent cover levels. There were however, were significant differences (P<0.01) among browsing pressures of the three browse species. The use of prescribed fire as a management tool without adversely effecting deer and elk populations looks promising. Prescribed fire can be used to improve habitat for mule deer and elk. The prescribed fire maintained sufficient thermal and hiding cover levels while increasing total forb cover including many important species considered important for mule deer.