Apparent climate-mediated loss and fragmentation of core habitat of the American pika in the Northern Sierra Nevada, California, USA
Panels depict mean summer temperature (MST) for historical conditions, 1910–1955 (current MST -1.45°C), current conditions, 2010 (2001–2010), and future conditions (2030, RCP 8.5, current MST + 1.33°C; 2050, RCP 8.5, current MST + 2.74°C). Fourteen degrees Celsius MST represents an approximate threshold above which pika occupancy becomes tenuous . Projections are the ensemble mean of 17 general circulation models . Temperatures from the mid-20th century and before (upper left panel) appear to have supported spatially continuous pika-habitable temperatures throughout much of the Tahoe region. Current temperatures (upper right) have seen the collapse of the Pluto triangle metapopulation, which occupied the isthmus of habitat connecting the crest of the Sierra with the Carson Range to the east. If pika response is governed by the temperature and dispersal thresholds observed in our study area, climate warming appears poised to cause extensive retraction and fragmentation of pika populations in the greater Lake Tahoe area within decades (bottom panels).