Resurvey of Historical Pika Records in California
AuthorStewart, Joseph A E
AdvisorPeacock, Mary M
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Anthropogenic climate change is emerging as a growing threat to biodiversityconservation, but the degree to which species have been, and will be, affected remains an open question. The American pika has become a model organism for examining the effects of anthropogenic climate change on montane species conservation and has been evaluated for protection under the United States and California Endangered Species Acts. Climate envelope models predict that pikas will be forced to higher elevations by climate change, eventually being "pushed off" the tops of mountains by high temperatures. Chapter one examines current occupancy patterns at 19 historically occupied sites in the in the Northern Sierra Nevada. Chapter two examines current occupancy patterns at 67 precise historical pika record locations across California. Using logistic regression and an information theoretic approach, I modeled current pika occupancy as a function of environmental variables (habitat, climate, etc.). Chapter one, with its small sample size, did not find a significant climate or elevation effect. Chapter two found that pikas are especially sensitive to summer temperature and talus habitat abundance. Forecasting this relationship to the future the best-preforming model predicts progressive site extirpations as summer temperatures continue to warm. Depending on the amount of climate change, the model predicts that by 2070, pikas will be extirpated from 63% to 94% of historical sites in California.