Resource depression, climate change, and mountain sheep in the eastern Great Basin of western North America

Strontium, oxygen, and carbon stable isotope analysis may be used in conjunction with archaeofaunal data to identify resource depression by demonstrating that prey were obtained from more distant locations. We use fauna from Five Finger Ridge, a Fremont site in central Utah, to demonstrate that relative abundances of mountain sheep (Ovis canadensis) declined during a period of increased summer precipitation. Strontium ratio values from this period indicate that sheep were acquired from different locations than the preceding period. Specimens from this period also show a moderate increase in carbon ratio values, suggesting that mountain sheep were acquired from higher altitudes. Oxygen isotopes do not vary between temporal periods, possibly the result of the countering effects of higher oxygen isotope values associated with increased summer temperatures and lower oxygen isotope values present at higher elevations. Collectively, these data support that there were localized population declines of mountain sheep that may be related to either climatic changes or hunting pressure.