Prior to European colonization, sagebrush steppe covered approximately 44 million ha of the Intermountain West, the vast areas of land between the Rocky Mountains and the Cascades and Sierra Nevada mountain ranges (West and Young 2000). Since then the sagebrush steppe ecosystem has experienced extensive changes (USDA Forest Service 1996, West and Young 2000, Bureau of Land Management 2002, Reid et al. 2002). Substantial portions of the region have been converted to agriculture and development (West and Young 2000, Bunting et al. 2002). Much of the remaining sagebrush steppe has been degraded through overgrazing by livestock, altered fire regimes, and invasion of introduced plants (Reid et al. 2002).