A relative of rabbits, tiny, cute and charismatic American pikas typically live in cool, mountain environments and find refuge from the hot sun under boulders and rocks. Because the animals are sensitive to high temperatures, some researchers in the recent past have predicted that as the climate warms, pikas will have to move to ever-higher elevations until they eventually run out of places toward the top of the world where they can go. Then, they’ll likely become extinct.
Because of that predicted scenario, some have even claimed that this beguiling, little herbivore is the proverbial canary in the coal mine for climate change.
But despite their outwardly cuddly appearance, American pikas are among North America’s toughest animals. And, surprisingly, we’re now finding out that this little creature is far more resilient in the face of challenging warmer temperatures than we previously believed.
Climate change conundrum
Although climate change is a serious threat to the survival of many species on Earth, according to a new, extensive review by Arizona State University Emeritus Professor Andrew Smith, published in the October 2020 issue of the Journal of Mammalogy, the American pika is currently adapting remarkably well.
Professor Smith didn’t set out to be a pika biologist when he began his work in the Sierra Nevada 50 years ago. But each pika study he got involved in increased his fascination with the diminutive mammals, and he’s focused on them ever since. In the recently published review, Smith presents evidence showing that American pika populations are healthy across their full range, which extends from Alberta and British Columbia, Canada, to northern New Mexico in the U.S.
Pika occupancy in potential habitats in the western North American mountains was found to be uniformly high. While parts of North America have seen losses in pika populations, most of those disappearances happened outside of the species’ core range. The Great Basin, a deserted terrain encompassing parts of California, Idaho, Oregon, Utah, Wyoming and most of Nevada, saw the majority of the population declines. However, Smith reports that sites that experienced significant pika disappearances did not deviate in temperature or precipitation from sites where pikas were still thriving. In fact, several areas of population loss were found close to other inhabited areas sharing a similar climate. As a result, he concluded, variables unrelated to climate are believed to be responsible for the decreases, such as livestock grazing.
Smith believes this is a sign that American pikas are a robust species and that most of the studies that have raised alarms about their fate are based on observances at a relatively small number of sites on the margins of the pikas’ geographic range.
Another explanation could be that in previous attempts to document pika habitats, many of the sites surveyed no longer were occupied. It was easy to surmise that due to rising temperatures, the pikas were migrating higher up, where the temperatures were more bearable.
By examining the largest set of records to date for occupied and vacant pika sites, Smith and his team also found that while the pikas are indeed moving to higher altitudes due to climate change, they are also inhabiting new territories with other types of weather conditions never before reported.
In fact, individuals were found at elevations spanning 7,600 feet, from 5,350 feet to above 13,000 feet, and traversing 40 mountain ranges across California, Nevada, Oregon and Utah.
Overall, pikas seem to be doing especially well in their core habitat (North America’s western mountain ranges). Professor Smith’s research team discovered 2,387 records of occupied pika sites, with 89 records of previously occupied sites that were later found vacant; and 774 records of sites that contain older signs of occupancy, but at which extirpation could not be confirmed. In the central Sierra Nevada, 98 percent of sites hosted healthy pika populations. The same statistic is true for sites monitored in Colorado.
Smith’s most interesting finding may be that pikas are apparently much more resilient than we thought, surviving in conditions colder and wetter—as well as warmer and drier—than expected. Bodie State Historic Park, Mono-Inyo Craters and Lava Beds National Monument in California; Craters of the Moon National Monument and Preserve in Idaho; and the Columbia River Gorge in Oregon and Washington (all hot, low-elevation sites) have active pika populations.
Understanding the American pika’s evolutionary history offers some insight into how the animal might fare against today’s changing world.
Believed to have migrated from Asia roughly 5 million years ago, pikas once inhabited parts of North America that no longer support modern descendants. For example, regions now uninhabitable for pikas—such as the Appalachian Mountains and the Mojave Desert—were home to their ancient ancestors because the global climate was much colder. Many pikas began to seek cooler temperatures upslope as the world began to warm.
However, not all pikas retreated to high-altitude habits. In fact, some pika populations learned to live in warmer, low-elevation sites. Smith found that pika behavior shifts in the heat and lower altitude: they decrease their activities, their diets diversity, and they make fewer noises. They also spend more time foraging at night when temperatures drop and spend much of the day in the shady nooks of their dens.
Pikas living along Oregon’s Columbia River Gorge, for example, eat moss almost exclusively—an unusual trait for the typical hay-munching pikas. Though these warmer, low-elevation colonies are not as numerous, it is promising to know that the species can adapt to different habitats.
However, while the future of the American pika may be more promising than we had hoped, we should not take this species for granted. Due to the relatively poor ability of pikas to disperse between areas, habitats that are lost are not likely to be recolonized, particularly considering our rapidly warming planet. From unprecedented glacial melt to extended droughts and wildfire seasons, the impacts of climate change are still being revealed. An assessment by NASA reports that global average temperatures have risen by more than 2 degrees Fahrenheit since 1880. They are expected to continue increasing; so, despite the general health of pikas across their range, losses often do represent a one-way street, leading to a gradual diminishing of some pika populations.
Fortunately, for now, at least, most documented cases of the local pika losses have occurred on small, isolated patches. Their preferred talus habitat in the major mountain cordilleras is larger and more contiguous, so the overall risk to them at the present time is low.
Professor Smith’s work clearly demonstrates that when considering conservation status, it’s important to incorporate all aspects of a species’ behavior and ecology. Because of the new review, we know that rather than facing extinction, American pikas are somehow persisting against great odds.
In the end, the key to pikas surviving climate change may be less about their climbing higher and more about our allowing wildlife to have some suitable, undisturbed pockets of refuge at every elevation.
Sadly, though, the human species may be the most unpredictable of all.
Here’s to finding your true places and natural habitats,