Poop-eating Pikas More Resilient to Climate Change than Previously Believed, Study Suggests
Pikas, a relative of rabbits, are determined not to become climate refugees, going so far as to shake up their diet in an effort to withstand rising temperatures, according to a new study published in the Journal of Mammalogy.
By observing populations of the small critters living out in the rockslides near the Gorge Trail by Wyeth, Ore., University of Utah biologists found the pikas are able to survive hot weather by consuming more moss than any other mammal.
"Few herbivores consume moss because it's so nutritionally deficient," said Jo Varner, a biology doctoral student and the study's first author. "The pikas in our study actually set a new record for moss in a mammal's diet: 60 percent."
Moss is 80 percent fiber, which means that eating it is "a bit like eating paper," Varner said. "Some fiber is good, but this is almost all fiber."
The secret appears to be in pikas' ability to produce a small portion of their feces in the form of so-called caecal pellets that they then reingest for nutrition.
"Pikas and rabbits and their gut microbes are the ultimate recycling factory," said Denise Dearing, a biology professor and senior author of the study. "They ingest low-quality food, over and over again, and turn it into high-quality protein and energy. The end product is six times more nutritious than the moss."
Consuming the moss that grows on the rocks where the pikas live allows the mammal to avoid venturing far beyond the shade of their habitat, which is key given their sensitivity to heat. At 6 inches long and one-third pound, the animals die if they spend more than two hours in temperatures above 78 degrees Fahrenheit.
"They basically are shaped like spheres, which is optimal for conserving heat," Varner said. "They have a thick fur coat and a high metabolic rate, which means they generate a lot of heat. The thick fur coat traps it, and so does their spherical shape."
Such vulnerability has turned pikas into something of a poster child for climate change, especially since populations in places like Nevada's Great Basin and areas of Colorado have gone extinct. The results, however, suggest "they may be more resistant to climate change than we thought," Dearing said.
The researchers said that, based on their findings, it might be a good idea for people living in the Northwest to avoid trampling over the moss covering rockslides while hiking and to restrain from collecting it for horticulture.