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The Impossibly Cute Pika’s Survival May Say Something About Our Own Future
发布日期:2024-11-23 12:20:14
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Early one August morning, on a rocky slope high in Montana’s Gallatin Range, biologist Chris Ray crouched on a boulder with a tiny, sedated furball in her hands. Ray has long, wavy salt-and-pepper hair and was wearing white nitrile gloves to protect the creature, a fist-sized denizen of the western mountains called an American pika.

Ray had captured the animal in a small metal “live trap,” and then coaxed it into a clear plastic tube primed with a cotton swab soaked in anesthetic. “Go to dreamland, buddy,” she’d cooed.

Now, she and a group of assistants sprang into action like a medical team in the operating room. They collected blood and urine samples in toothpick-sized glass vials, used tweezers to pick mites from its ears and collect fecal pellets, slid hair and tissue samples into envelopes, and gave the pika a shot of plague vaccine. Ray talked the group through each step, then weighed the critter and tagged its ear before setting it free among the rocks.

Biologist Chris Ray has been studying pikas in the western United States and documenting their changing populations for three decades. Credit: Nicholas Kusnetz/ICN

Ray is a research associate at the University of Colorado, Boulder, and she has been coming to this site every year since 1988 to chronicle the pikas who live here, making it one of the longest-running research projects of one of the West’s most adorable creatures. She came when she was pregnant with her son Max, now 11, and she came the following year too, nursing him in between bouts of field work. She wants to know what allows pikas to scratch out an existence in such an unforgiving environment, and increasingly, what may be contributing to their decline.

Pikas have become a cuddly proxy for the pernicious effects of climate change, and for good reason. The rabbit relatives are highly sensitive to temperature changes. They live high in the mountains, where temperatures are warming faster than the global average. And because pikas occupy a habitat that’s critical to life across the West—mountain snowmelt is the primary source of water for the farms and cities that have fueled the region’s growth—pika research may have a lot to say about our own future, too.

Researchers have linked rising temperatures to the decline of pikas across large areas of their range, which covers mountain chains from New Mexico to British Columbia. But Ray and her peers are only beginning to understand the mechanisms of how climate change is affecting these animals, and their work tells a story not just about what we know, but about how much we still don’t. Some of their findings challenge the narratives of climate demise that have trickled out to the general public. And Ray’s most recent data suggests the picture may be even worse than scientists had thought.

Even as strengthened climate models give more accurate forecasts of a warmer future, there remains tremendous uncertainty about what that will mean for critical ecosystems, from Amazonian forests to glacier-clad mountains. Will they evolve over time? Could they suddenly collapse? The search for answers can provide a clearer sense of what lies ahead for us, too.

High in Montana’s Gallatin Range, pikas live in rocky outcroppings, or talus slides, that provide protection and shelter. Credit: Nicholas Kusnetz/ICN

Part of this uncertainty, Ray says, is that even after decades of research, scientists still have only glimpses into the inner workings of complex ecosystems. But part of it may be that the climate is changing so fast now, it’s hard to keep up.

“You’ve been there every year for 30 years, you’d like to feel like you start to understand the system,” Ray told me recently, thinking back on the summer’s work. “And 15 years into it, I started to feel like I understood the system. But 15 years later I don’t.”

A Laboratory in the Sky

Chris Ray first arrived in Montana as a college student in 1988, ready for work with a rifle in hand. Her professor, Michael Gilpin, was an early conservation biologist at the University of California, San Diego. His field was concerned with conservation, but also its opposite: extinction. Researchers wanted to know what happens when humans carve up wild landscapes, breaking up wildlife populations and isolating them from each other. Are these fragmented populations more vulnerable to extinction? And if they disappear from an isolated spot, will they ever return?

Pikas offered a convenient study subject because their populations are naturally isolated in high-mountain rock slides that are often miles apart, separated by forests and valleys. Gilpin’s plan was to find a population and then snipe them out with a pair of .22s to see how long it took for them to come back.

Such science-by-violence was not unheard of then. The famed Harvard biologist E.O. Wilson was once part of a study that involved “defaunating” six small islands in Florida with poison gas in order to watch as the bugs recolonized.

Gilpin’s pika extermination, however, was not to be. “I saw my first pika and I said, ‘Mike, we can’t shoot these animals out,’” Ray recalled. She had been drawn to science to help protect animals, not to kill them. She peppered Gilpin with reasons that the experiment was unlikely to succeed, from the pragmatic (they would never be able to shoot all of the tiny, zippy creatures) to the scientific (they had no baseline data). “He said, ‘Agh, I guess you’re right. I guess we’ll have to start a study.’”

They set about marking the rock slides—some boulders still display the original spray paint, though Ray now uses GPS—to begin to get a sense of how many pikas lived in the canyon, how far apart they spaced themselves, and how stable the population was. With Gilpin’s blessing, Ray took over the study two years later and has been trekking there every summer since. Over time, her primary focus has become how long the pikas live, and what factors—including temperature, which she’s measured with sensors since 2001—may influence their survival. No shots have ever been fired.

Over the years, Ray has collected a posse of students, friends and admirers who spend a week or two each summer at the camp as assistants. This year, they numbered around 10 and included an undergraduate who knew little about pikas but was eager to learn, a postdoctoral researcher taking notes for her own research, and a friend who runs a small conservation group in Bozeman.

They’ve built something of a community: Some bring their own children, who have grown up here with Max, and the kids sometimes tag along on the field work, telling each other jokes in the background as the researchers catalogue data.

But the main draw, of course, is the pikas, which everyone adores. When asked to describe why she studies them, the postdoctoral researcher, Jessica Castillo Vardaro, spoke earnestly about the value of scientific pursuits before pausing to add, “and they’re really cute.” Another scientist on the team set her personal email address to “pikabeast.”

To track the causes of pika population changes, Ray catches and briefly anesthetizes the tiny creatures. Credit: Nicholas Kusnetz/ICN

It’s this passion that brings Ray here as well. She doesn’t have funding for this research. (“Every year, my business as a scientist loses about $5,000 to support my pika research habit,” she said mirthfully.) She says she’s never tried to get funding for the Montana work because she has plenty of other deadlines from the grants she’s received for other research—she has another long-term research site monitoring pikas in Colorado, close to her home.

“When I see a little fluffy thing like a pika, a tiny little thing, and then I see some of the locations where it’s managed to eek out a living, I’m just fascinated,” she said while washing dishes in the camp after a long day of work. Meadows cluttered with wildflowers in yellow, scarlet and violet lay beyond the edge of the camp, and beyond that a pair of mountain goats clattered up the cliffs that circle the canyon. “I want to know, how do they do it? I want to get there. I want to understand, how does it happen?”

The data that Ray and her helpers have collected in Montana has influenced dozens of her papers about pikas over the years, from studies modeling the effects of climate change on their range to measuring “fecal stress metrics.” And the work she’s done here and in Colorado have made Ray one of the most respected experts in the field.

Once they catch a pika in a “live trap” and anesthetize it, Ray and her assistants collect blood, hair and other samples. Credit: Nicholas Kusnetz/ICN

“Her data and her scientific acumen is probably the best out there that we have,” said Jennifer Wilkening, a biologist with the Fish and Wildlife Service who studied under Ray for her doctoral work. Wilkening calls Ray “probably the number one expert on pikas” in the country. What sets Ray apart, Wilkening and others say, is that she has kept studying the same location for so long. “This is one of the reasons why she is the gold standard. There is nobody else that has a dataset like that.”

That dataset, after 30 years, is beginning to yield clues that suggest that what happens to pikas may be indicative of important changes in the ecosystem that have much broader implications for the West.

Climate Signals

In the early 1990s, Ray was beginning work on a dissertation that was going to explain localized prehistoric extinctions of pikas in the Great Basin, an arid expanse of isolated mountain chains between the Rockies and the Sierra Nevada.

Paleontological records had already shown that pikas had inhabited a wider range in the Great Basin during the last ice age, some 20,000 years ago. The assumption was that as temperatures rose, pika habitat shrank.

The American pika may not be as iconic as bison or grizzly bears, but these relatives of rabbits are almost impossibly cute as they dart from rock to rock carrying wildflowers that they cache as food. Credit: Nicholas Kusnetz/ICN

Climate change hadn’t really entered the discussion, at least not as a current threat to pikas. But as Ray traveled across the ranges trying to verify historical records, she started noticing empty rock slides in places where pikas had been recorded decades earlier. It was like a bell ringing in her mind. She was witnessing a decline in motion.

“I just totally thought, ‘it must be climate change.’”

The findings remained merely a hunch, however, until she met a Ph.D. student named Erik Beever who was doing similar work, collecting early 20th century records of pikas from across the Great Basin and visiting those sites to see if the animals were still there. Beever would go on to publish a paper in 2003 that largely set the foundation of the theory that climate change is wiping out pikas. He found that pikas had disappeared from nearly a quarter of the locations he visited, and hypothesized that extreme heat was forcing the pikas to spend more time hunkered underground, or maybe was affecting the vegetation they eat or even baking them to death.

Beever later expanded on the work and found declines across a larger area, including northern California. Pikas disappeared from Utah’s Zion National Park within the past decade, he wrote in a 2016 paper, and are nearly gone from nearby Cedar Breaks National Monument. He’s been studying pikas at the southern edge of their range at Bandelier National Monument in New Mexico, where Beever said officials seem to have already written off the creature’s future:

“It took me aback,” he said. “Their leadership said, ‘We’d like to have you here and come back to monitor pikas until they’re gone.’”

A Picture Emerges

Still, despite the growing body of evidence linking climate change to pikas’ declines, recent research has shown how messy the picture is. Some studies suggest pikas may be more resilient to warming temperatures than previously thought: A paper published last year describes pikas inhabiting many sites across the Great Basin that are lower, hotter and drier than researchers consider ideal.

Other work points to the counterintuitive finding that, while climate change is very much a threat, it’s not the summer heat that’s killing the pikas. One recent study, which tracked pikas in the North Cascades in Washington state, found that low-snow years led to population declines at lower and mid-elevations. But the mechanisms driving the declines were different: At low elevations, snow-drought likely led to a scarcity of vegetation for the pikas to eat and cache for the winter. A little higher up, where temperatures were colder, snow provides an insulating blanket to pikas, and if there’s not enough snow, the animals can suffer enough to knock down their reproductive rates, or even die from cold. That’s right: because of climate change, pikas may actually be freezing to death.

What’s true in the North Cascades, however, may not be in Nevada’s Ruby Mountains, leading Ray and others to caution that it’s hard to make broad generalizations. In some areas, including Idaho’s Craters of the Moon National Monument, pikas survive stifling heat thanks to underground ice deposits. In the Columbia River Gorge, they survive near sea level thanks to the thick overstory and moss that keep temperatures tolerable through the summer months.

The accumulation of research points to the incremental, imperfect nature of the scientific process. The studies offer snapshots that, however clear, can only suggest at what is beyond their margins.

Ray says she’s seen a decline in the number of pikas in parts of the canyon in recent years, a trend she thinks is likely driven by climate change. Credit: Nicholas Kusnetz/ICN

Ray does believe there is a through-line, however, that tends to hold true: that the pika’s fate is tied, above all else, to snow and ice. That’s one reason she’s been troubled by what she’s seen in Montana these past few years.

Her study site in the Gallatin Range is prime pika habitat: high-elevation, tucked into a cirque that still holds patches of snow late into summers. Models suggested it would be years, still, before climate change affected pikas in places like this.

But the past few years have been stark. “It’s already gotten so much more comfortable to be up there,” Ray said. When she started her research, “it was thick with mosquitos and freezing cold and snowy in the summertime and constantly raining. It was a wetter, colder climate, and for humans it wasn’t so much fun. Now it’s like going to the beach.”

The day after Ray and her team were cataloguing pikas on the canyon’s southeastern face last August, they headed to the opposite side to place traps for the following day. The sun was warming the slope in the early morning. The rocks were dry and bare. They were looking for active pika sites where they would position traps, but in patch after patch, they were struggling to find any.

“This slope used to be the nerve center of the population,” Ray said, growing exasperated as the morning wore on. “But in recent years, I’ve been seeing fewer and fewer.”

Pikas collect plants and grasses that they store under rocks for winter. The piles help researchers identify where pikas live. Credit: Nicholas Kusnetz/ICN

Maybe there’s something else going on, she said—the vaccines she was injecting into pikas were to see if plague may be affecting the population—or maybe the warming is coming faster and pikas are more sensitive to changes than she’d thought.

Despite three decades of research on the pikas in the canyon, she’s yet to publish on the study as a whole. She says she never felt like she had enough data to pull a clear signal out of the noise of annual variation.

But after last summer, she’s starting feel differently. “Something’s going on,” she said recently. She’s also seen a sharp decline in the pika population in her other research site in Colorado in recent years, as winter snows have melted earlier in the year. There, too, she says, no one expected declines to come this soon. “I thought I had more time.”

A Bleak Future

What will become of the pika? Even in a warming world, pikas may persist and even thrive in some pockets. In other places, we may be able to relocate them to new habitats as temperatures rise. (Ray co-authored a paper arguing that pikas are a prime candidate for such “assisted migration.”)

But if Ray is right, and pikas live or die according to the existence of snow and ice, the animal’s future is likely bleak.

Ray’s team has founding a dwindling number of pikas in the canyon in recent years. The declining snow cover through the winter means a loss of insulation for their rocky homes. Credit: Nicholas Kusnetz/ICN

Already, according to one study, Western snowpack has declined by about 20 percent since 1915, a loss greater than the storage capacity of Lake Mead, the West’s largest reservoir. While some winters will still bring loads of snow, climate models consistently predict that more precipitation will come as rain, and what does come as snow will melt faster. Maps of the snowpack’s decline bear a grim resemblance to maps of pikas’ shrinking habitat.

Pikas play a key role in moving and recycling nutrients by caching vegetation for the winter. They’re an important food source for weasels and birds of prey. Ray says no one knows what happens to these mountain ecosystems after pikas are gone.

And the connection with snowpack firmly ties the pika’s fate to our own. Snow is the primary source of water for the West’s cities, farms, power plants and more. Western development is built around the assumption of snow acting as a natural reservoir that releases water through the summer and early fall. The challenges for Western development in a less snowy future are hard to overstate.

Laurna Kaatz, a climate scientist with Denver Water, the utility that serves drinking water to 1.4 million people in the city and surrounding suburbs, closely examines the same high-mountain ecosystems that Ray does. She said questions about how warming will affect those ecosystems mean that water agencies like hers have to plan for multiple futures. “We need to recognize we’re dealing with uncertainty, and we’re not necessarily going to recognize a trend before we see a trend.”

The mountain snowpack is critical for the pika’s survival and for farm and communities across the West. While wisps still cling on late into summer here, the snowpack is projected to decline in coming decades. Credit: Nicholas Kusnetz/ICN

As Ray and her team scoured the western slope of the canyon that August day, struggling to find pikas, she threw her arms up and broke out in song, the Fugs’ “Nothing”—Monday, nothing, Tuesday, nothing…

Finally, the group moved on and approached a patch that Ray said was nearly always occupied. A bright, bountiful green pile of grasses and flowers sat under a rock. A pika zipped into a crevice. At the bottom of the slope, a stream gurgled out from under the rocks as the researchers sat silently, waiting for the animal to reemerge.

Top photo credit: Ann Schonlau/Rocky Mountain National Park/CC-BY-ND-2.0

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