Oregon Field Guide

Pikas return to the Gorge — or so researchers think

By Jule Gilfillan (OPB)
Oct. 30, 2020 1:12 p.m.

Confirming the return of pikas following the Eagle Creek Fire has been tricky.

When the Eagle Creek Fire roared through the Columbia River Gorge in September 2017, pika researcher Johanna Varner could only watch in dismay.


“I think that I first saw information about the fire on Twitter and I was following the hashtag ‘Eagle Creek Fire’ and I just like sat all day, hitting reload on the hashtag, looking for new maps of the fire progression and trying to figure out like, are they burning my field sites and how are my pikas doing?” Varner remembered. “You know you can’t spend that long in a place and not feel a real personal connection to it.”

Now a researcher at Colorado Mesa University, Varner has been documenting this unique population of the cute, furry creatures in the Gorge since 2011.

Related: OPB's Eagle Creek Fire coverage

American pikas are unique here because they typically favor high elevation scree fields and snowy climes where their underground dens can stay at a constant, cool temperature. Using sensors that measure the temperature both on the surface and a meter below ground, Varner determined that pika dens in this unexpected location stayed cool enough for the animals to live at elevations only a few hundred feet above sea level.

Moss covers talus slopes in the Columbia River Gorge before the Eagle Creek Fire

Moss covers talus slopes in the Columbia River Gorge before the Eagle Creek Fire

Johanna Varner

“We’re finding temperatures in the rockslides are very unusual. About a meter below the surface it stays a pretty cool and constant 45 degrees, every day and every night throughout the summer. So even though it could be 90 degrees for us at the surface walking around, the pikas are actually experiencing a much cooler and stable microclimate and temperatures in this rockslide,” she said.

With a focus on how climate change may impact the pikas over the long run, Varner’s research suggested that the moss that covers the talus slopes in the Gorge seemed to be acting like a thick blanket of snow does at higher altitude, and might be a sort of climate change refuge for the pikas that live here.

“Some of these rockslides might be really quite deep, and there might actually be year-round ice where the snow and ice sort of trickled down into the rocks.”


Remarkably, the sensors Varner had embedded in the slopes for her research continued to measure temperatures during the fire. And even with the insulating moss mostly burned off, the results they recorded were surprising.

Temperature sensors near the surface did not fare well during the Eagle Creek Fire

Temperature sensors near the surface did not fare well during the Eagle Creek Fire

Johanna Varner

“I had sensors at the surface of the fire and some of those sensors didn’t fare so well. But the sensors that were down below the rocks were miraculously pretty intact. And surprisingly to me, the temperatures in the rockslide during the fire were actually quite cool and quite constant. They never got above about 6- to 8-degrees Celsius, which is something like in the low 40s in Fahrenheit.”

That’s about the temperature inside a refrigerator. So, even as the fire was raging and exploding Varner’s sensors at the surface, the pikas' dens were staying pretty cool.

Even with those life-sustaining temperatures, when Varner’s team finally got access to the study areas in the summer of 2018, they found that resident pikas had disappeared from about half the sites they occupied the previous year. Surveys in 2019 showed an improvement.

Related: Pikas: 'adorable masters of the high country'

“We are seeing more pikas out there in 2019 than we did in 2018. About half of those sites that went from occupied to unoccupied have now been recolonized.”

Previous studies also give Varner a reason to be optimistic that her group of pikas may rebound.

“I think that there are a lot of parts of the Gorge that actually the fire is going to prove to be sort of stimulating of new vegetation for pikas. That’s kind of a similar pattern to what we saw on Mount Hood in 2011 after the Dollar Lake Fire; some of these more intermediately burned sites tended to actually have the highest abundance of pikas two to three years following the fire.”

So how are the pikas doing in 2020?

After COVID-19 shut down many of the areas Varner studies in the Columbia River Gorge in March 2020, the Oregon Zoo followed suit and suspended the Cascade Pika Watch teams she depends on for on-the-ground work like conducting population surveys and replacing dead batteries in sensors.

“Unfortunately, because of the pandemic, we’re probably gonna lose another year of occupancy data here,” she lamented. “What that would have told us would have been has the population really rebounded, are they continuing to rebound or was it just sort of part of this annual fluctuation?”

That’s a question Varner and her colleagues may have to wait until next year to answer.