American Pika Populations May Be Declining, Says Study

A study has found that American pika populations may be declining near Rocky Mountain National Park due to climate change. Researchers discovered that the “recruitment “of juveniles at the research site seems to have plummeted since the 1980s. In other words, the populations are becoming dominated by older adults, with fewer young pikas being born, or migrating in, to take their place.

The pika is an iconic animal of the Rockies’. It is a small fuzzy mammal with round ears and is about the size of a rat, although it’s more closely related to a rabbit. Pikas will often greet hikers with loud squeaks.  

“It’s a fun encounter when you’re hiking on a trail in the Rockies and a pika yells at you,” said Chris Ray, lead author of the study and a research associate at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder. “If you don’t have that anymore, your experience in the wild is degraded.”

From 1981 to 1990, Charles Southwick, a former professor at CU Boulder, set out to follow the pika populations at Niwot Ridge. His team trapped and tagged pikas, which tend to stick close to taluses, or piles of rocks.

For the current study (attached), researchers surveyed pikas living at the same site, the Niwot Ridge Long Term Ecological Research site, in 2004 and from 2008 to 2020. They then compared their results to similar surveys undertaken by Southwick.

Based on their calculations, the proportion of pikas the researchers trapped that were juveniles fell by roughly 50 percent from the 1980s to today, suggesting that younger pikas could be growing rarer on Niwot Ridge.

Scientists have long predicted that climate change might threaten pikas in the American West, in large part because they can only survive in a narrow range of temperatures.

“Pikas don’t pant like a dog. They don’t sweat,” Ray explained. “The only way they can release their metabolic heat is to get into a nice, cool space and just let it dissipate.”

Young pikas may also have trouble migrating through the Rockies as temperatures continue to warm. To cross from one mountain habitat to another, pikas first have to climb down in elevation, facing hot conditions in the process.

However, Ray and her colleagues can’t yet pinpoint the reason pika recruitment may be declining at Niwot Ridge. They do note that summers have been growing warmer at sites across the Rocky Mountains—a concerning bellwether for ecosystems that humans depend on.

“The habitats where pikas live are our water tower,” Ray said. “The permafrost, or seasonal ice, that’s underground here melts later in the summer and helps replenish our water supplies at a time when reservoirs are draining.”

One 2015 study predicted that pikas could disappear entirely from Rocky Mountain National Park by the end of the century.