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Climate-vulnerable pikas may be surprisingly resilient to wildfire

These high-elevation creatures may find insulation in talus fields, according to new research.

 

As the West transforms into a tinderbox defined by hotter summers and drier winters, we Homo sapiens will have to rethink our relationship with fire: Get ready to part with your wood-shingled house smack dab in the wildland-urban interface, for instance. But how will other animals weather our fire-prone future? Research suggests that at least one species is well prepared to survive the flames — and it’s probably not the creature you would expect. 

The new study, published last month in the International Journal of Wildland Fire, comes courtesy of Johanna Varner, a recent Ph.D. graduate from the University of Utah with a passion for Ochotona princeps, the American pika. Pikas, an adorable, baseball-sized relative of the rabbit, have a notoriously poor tolerance for heat; as a result, they’re widely considered among the species most susceptible to climate change. As temperatures have climbed around the West, low-elevation pika populations have blinked out, and scientists fear that warming will push high-altitude pikas ever upward until they eventually run out of mountain.

Climate change cares not for the pika's cuteness.
Wikimedia Commons user caddymob

For her Ph.D., Varner intended to study an unusual band of pikas in the Columbia River Gorge that was somehow flourishing at low elevation. To figure out how those pikas were surviving, though, she needed to compare them to a more typical population — a control group. She chose some pikas on the north face of Oregon’s Mount Hood, and in the summer of 2011 installed temperature recording devices in the rocky talus slopes on which pikas shelter. So far, so good.

A week after Varner surveyed the area, however, lightning ignited the Dollar Lake Fire, a blaze that eventually burned 6,000 acres. When Varner returned to the mountain in June 2012, many of her control sites, once forested in hemlock and cedar, had been transformed into moonscapes. “My whole thesis had gone up in flames,” she recalls.

When Varner recovered from the shock, however, she realized that nature had given her an opportunity. Forget the low-elevation pikas. She had a new question to investigate: How would these montane critters respond to wildfire?

Varner quickly began to suspect that the pikas had fared well. For starters, her temperature recorders, which she’d assumed had melted, were perfectly intact: The talus fields had insulated them from the conflagration. That suggested that the pikas could have hunkered down and kept cool, too. “I can tell you where I’m heading if I ever get caught in a wildfire: I’m climbing under those rock piles,” Varner says.

Sure enough, when she and her field assistants canvassed the blackened mountainside, they heard the pika’s distinctive peeps almost everywhere. The critters were most abundant in areas that had been moderately burned, where the fire may have stimulated the growth of tasty new vegetation. When Varner returned in subsequent years, she realized that pikas were not only inhabiting the burned areas but likely reproducing; when she sampled their scat for signs of stress, she found that pikas living in burned zones were no more anxious than their neighbors. Varner gives credit to pikas’ catholic diet, which allows them to nosh on whatever grows in wildfire’s wake.

Don't let the scorched trees fool you — that talus slope makes for prime pika habitat.
Johanna Varner

Varner cautions that, while Pacific Northwest pikas might be fire-resilient, other populations — in the Great Basin, for instance — may not prove so hardy. Still, her findings jibe with research suggesting that many species respond well to wildfire. Sometimes, those responses entail complex ecological relationships. After the 2007 Angora fire torched the southwest shores of Lake Tahoe, for instance, scientists observed three woodpecker species drilling tree cavities in burned areas. When the woodpeckers moved out, a host of new tenants, from kestrels to flying squirrels, colonized the holes the ‘peckers had created.  

Yet Angela White, research ecologist at the U.S. Forest Service and co-author of the woodpecker study, cautions that we still don’t know how wildlife will cope in a future seared by more intense flames. After the Angora Fire, White found the Western tanager, a bird that prefers lush, green forests, foraging inside the burned area. But the tanager wasn’t living within the black — it was commuting from nearby patches of unburned habitat. If a larger, more intense fire had overrun the whole region, the tanager might have been out of luck.

“A lot of species do well with a little bit of fire,” White says. “But how much fire can they handle?” 

Indeed, a version of that distinction appears in Varner’s study. After the Dollar Lake Fire, pikas were most abundant in moderately burned areas — but they were least abundant in severely burned places, where the blaze likely incinerated their food caches, called haypiles. Their stores destroyed, those pikas may not have survived the winter.

Even in the most badly scorched zones, however, the diminutive lagomorphs gradually recovered. To Varner, their comeback suggests that O. princeps reputation might have to undergo revision. “We think about pikas as these delicate little flowers that are the certain victims of climate change,” Varner says. “But they’re more resilient to disturbance than we would’ve expected” — at least for now.

Ben Goldfarb is a correspondent for High Country News.