Opportunities to quantitatively assess responses of ungulates to mineral extraction have been limited. Reasons for this dearth of research include a lack of adequate funding, available personnel, and logistical constraints. In 1992, a request was submitted to the Bureau of Land Management by a mining company for permission to extract and process gold ore in the Panamint Range, Inyo County, California, near a spring presumed to be critically important to mountain sheep, Ovis canadensis. Ensuing compliance with the National Environmental Policy Act resulted in funds to monitor effects of mining activities on mountain sheep inhabiting that area. Because funding was not released until ~8 months prior to construction and operation of the mine, we were unable to adequately address the pre-mining ecology of sheep in the "affected" area. We therefore employed a simultaneous treatment-control study designed to test several hypotheses regarding effects of mining activities on habitat selection, demographics,home-range dynamics, foraging activities, and composition and quality of diet for mountain sheep during 1995-1997. During our 3-yr study, we radiocollared and monitored 86% (n = 19) of all adult female sheep known to exist within the mined (treatment) and nonmined (control) areas. Size of annual home ranges, composition of diet, and ratios of young to adult females did not differ between female sheep inhabiting mined and nonmined areas. The nonmined area contained more annual plants, succulents, and perennial forbs than did the mined area, whereas abundance of shrubs, quality of forage, and relative abundance of carnivores did not differ between sites. During spring, female sheep adjacent to the mine spent more time foraging and had a lower-quality diet than those in the nonmined area. Conversely, during summer and autumn, female sheep from the mined area spent less time foraging than those in the nonmined area, but continued to have a lower-quality diet. All females were nearest water in summer compared with other seasons. During all seasons, females selected sites with more mixed-woody scrub, lower elevations, steeper slopes, and less visibility than available at random locations. We observed the greatest disparities between study areas in time spent foraging and diet quality during summer. In summer, females from the mined area were nearest to the mine; amount of explosives used, frequency of blasting, and amount of ore hauled from the mine were greatest during that period. Because of their reliance on a source of permanent water adjacent to the mine during summer and autumn, we hypothesize that female sheep from the mined area spent more time vigilant during those seasons and, consequently, less time foraging than conspecif ics in the nonminedarea. If outcomes we observed persist for mountain sheep in the mined area, reduced nutrient intake could have demographic consequences for that subpopulation. Thus, providing a reliable source of water away from the mine, or reducing mining activity during summer, may benefit mountain sheep that currently use areas adjacent to the mine.
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