American pika disappears from large area of California's Sierra Nevada mountains


Study documents local extinction of pikas from the largest area yet reported and projects climate change will cause drastic decline for the charismatic mammal within decades.

The American pika, a small mammal adapted to high altitudes and cold temperatures, has died out from a 64-square-mile span of habitat in California’s northern Sierra Nevada mountains, and the cause appears to be climate change, according to a new study published August 30 in PLOS One.

Researchers surveyed pika habitat throughout the north Lake Tahoe area and found that pikas had disappeared from an area that stretches from near Tahoe City to Truckee, more than ten miles away, and includes Mount Pluto. This local extinction is the largest area of pika extinction yet reported for the modern era.

“The loss of pikas from this large area of otherwise suitable habitat echoes prehistoric range collapses that happened when temperatures increased after the last ice age,” said lead author Joseph Stewart, a Ph.D. candidate at UC Santa Cruz. “This time, however, we’re seeing the effects of climate change unfold on a scale of decades as opposed to millennia.”

Hikers and backpackers can still see pikas in the mountains surrounding the area of extinction. “Mount Rose and Desolation Wilderness are still great places to see pikas,” Stewart said. But not for long—the study forecasts that by 2050 climate change will cause a 97 percent decline in suitable climate conditions for pikas in the Lake Tahoe area.

Pikas, related to rabbits and hares, are about eight inches long with a stout body and round ears. They spend their summers carrying mouthfuls of grass and wildflowers from mountain meadows to “haypiles” tucked away in the rocky habitat they call home.

“The classic image of a pika is one hopping from rock to rock with a little ‘bouquet’ of wildflowers in its mouth,” said coauthor David Wright, recently retired from the California Department of Fish and Wildlife.

Pikas don’t hibernate, but rather use their furnace-like metabolism and thick coat of fur to stay warm during winters under the snow. “A larger haypile acts as insurance policy against winter starvation,” explained Stewart. “But the same adaptations that allow them to stay warm during winter make them vulnerable to overheating in the summer, and when summer temperatures are too hot, they can’t gather enough food to survive and reproduce.”

In order to confirm that pikas are now extinct from the 64-square-mile (165-square-kilometer) area, the authors searched for pikas over the course of six years, from 2011 to 2016, looking for evidence of pika activity and camping next to pika habitat to listen for the animal’s distinctive calls. “We found old pika fecal pellets buried in sediment in nearly every patch of habitat we searched,” said Stewart. “But the animals themselves were conspicuously absent.”

Continue reading at University of California, Santa Cruz

Image via Alison Henry, University of California, Santa Cruz