I have been studying pikas, little cousins of rabbits, for over 50 years and am never tired of looking at them. These tailless, egg-shaped balls of fluff live mainly in cool mountainous environments in heaps of broken rock called talus.
During the summer, observers can see that pikas gather flux of grass and leaves in haystacks that will serve as food supplies during the winter. Their light brown coats blend well with their surroundings, so it is easiest to see when they are sitting on prominent rocks and calling to warn other pikas of their presence.
When fellow hikers see me seeing pikas in the Sierra Nevada, California, they tell me they have read that these animals are dying out. I collected a stack of press releases that say exactly that. But based on my recent research and a comprehensive review of more than 100 peer-reviewed studies, I believe this interpretation is misleading.
Limited by climate
As I showed in my early research, the biology of Pikas suggests that it is likely to be affected by a warming climate. Most importantly, their normal body temperature is high and there is a risk that they overheat when active in hot environments. When the temperature is warm, pikas retreat into the much cooler depths of their talus habitat.
Temperature also plays a role in the ability of pikas to move from place to place. Warm weather hinders their movements, while cooler temperatures enable them to colonize new habitats more freely.
Here’s a little ancient history informative. Pikas originally came from Asia to North America and spread across the continent during colder times about five million years ago. Their remains were found in caves in the Appalachian Mountains and in the Mojave Desert – places where picas no longer live.
American pikas live mainly in alpine and subalpine mountain ranges extending south from central British Columbia and Alberta to the Rocky Mountains of New Mexico and the Sierra Nevada of California. Andrew Smith, CC BY-ND
As the world’s climate warmed, pika populations retreated to the high mountains of the western US and Canada. Today, they occupy the most available talus habitat in these areas – evidence challenging the pikas-on-the-edge story.
Recent surveys, for example, have found picas at 98% of 109 suitable locations in Colorado, and at 98% of 329 locations in central Sierra Nevada. One study of historic pika sites in the national parks of Lassen, Yosemite, Kings Canyon and Sequoia in California found no evidence that pikas moved to new sites or higher altitudes due to new climate change.
Pickles in hot environments
In contrast, most sites where researchers believe that picas have disappeared are small, isolated, and often affected by human activities, such as grazing by livestock. These sites are usually lower and warmer than sites in the core range of Pikas.
Many of these areas are in the Great Basin – a large desert area that stretches across most of Nevada and parts of Utah, Idaho, Wyoming, Oregon and California. A series of studies on a small number of marginal Great Basin sites previously occupied by pikas contributed disproportionately to the narrative that pikas are likely to be threatened.
To investigate the overall picture in this region, I worked with state and federal officials on a 2017 study that identified 3,250 site records of pika habitat. Pikas were present at 2,378 sites, not at 89 sites where they had been seen in 2005, and absent from 774 sites that contained only ancient signs of pika occupation.
The extinct and old sites had the same temperature and precipitation ranges as sites where there were still pikas. This suggests that non-climatic factors caused Pikas to disappear from the vacant places.
Pikas have disappeared from some parts of the Great Basin, but climate change may not have been the cause. Kmusser / Wikipedia, CC BY-S
Pikas is still in other conspicuously hot places, such as the ghost town of Bodie, California, the nearby Mono Craters and the Craters of the Moon National Monument in Idaho. In these places, pikas migrate in the cool corners of their talus habitat during the hottest part of the day and often eat at night.
In my research, I also found that pikas were much less active and made far fewer calls on these low-altitude sites compared to pika populations with a high peak. In low-peak areas, pikas consume a diverse diet of large plants, such as large sap and bitter brush, which is very different from the plants they ate at high altitudes. Some have not even managed to build their distinctive large hay poles.
Another atypical pika population lives near sea level in the Columbia River Gorge in Oregon. Here, too, they adapted well to a very different habitat and survived all year on a diet consisting mainly of moss. They defend the smallest areas of any pika, and when it gets hot, they simply move from the talus and stroll in the shade of the nearby forest.
A Future for Pikas
Based on my review of dozens of studies, it appears that pika populations are safe in their core range – the mountains in western North America with a large and fairly well-connected talus habitat. In these areas, they can move from one habitat to another without going through areas that are dangerously hot for them.
The fact that pikas have also adapted to a number of marginal, warm environments suggests to me that they are more resistant to climate change than many studies have found in the past. Most species show losses near the edge of their geographic ranges, simply because individual animals in those areas live in conditions that are less than ideal for them. That does not mean they are extinct.
Climate change is the most important issue facing the world at present, which is why it is especially important for scientists to communicate accurately to the public about it. In my opinion, the fact that pikas deal with and change their behavior as a result of changing conditions is news to future physicists looking for one of nature’s most charismatic mammals.
Andrew Smith is an emeritus professor of life sciences at Arizona State University.
Disclosure Statement: Andrew Smith does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has not disclosed any applicable commitments outside of his academic appointment.
Replace with permission from The Conversation.
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