Winter on the Tibetan Plateau in Asia is unfriendly to pikas. Its barren, windy highlands often dip below –30° Celsius (–22° Fahrenheit). At those temps, the grass that pikas usually eat becomes dry and brittle. It would seem like the perfect time for these rabbitlike mammals to hibernate. Or stay warm by munching on stores of grass in their burrows. That’s what North American pikas do.
But not the plateau pika (Ochotona curzoniae). These critters continue foraging in winter. To conserve energy, plateau pikas drop their metabolism by about 30 percent. Some also resort to eating an unusual food: yak poop. Researchers reported their findings July 19 in the Proceedings of the National Academy of Sciences.
Cameras at four sites on the Tibetan Plateau captured the pikas’ winter routine. That footage showed that pikas often brave the cold to find food. “Clearly they’re doing something fancy with their metabolism that’s not hibernation,” says John Speakman. He works at the University of Aberdeen in Scotland. As an an ecophysiologist, he studies links between the environment and how an animal’s body functions.
Speakman and his colleagues measured how much energy 156 individual pikas spent each day in summer and winter. The team also implanted 27 animals with temperature sensors. What they found surprised them. Many animals that don’t hibernate keep warm in winter by using more energy. But these pikas did the opposite. On average, in winter they used 29.7 percent less energy per day. They did this in part by cooling their bodies by a couple of degrees overnight. The animals also were less active than in summer.
Sites with yaks had more pikas. And those pikas were even less active than the others. That puzzled the researchers. But then, “we found a sort of half-eaten yak turd in one of the [pika] burrows,” Speakman says. Eating poop can cause sickness. But yak dung could be an abundant, easily digestible meal for pikas with few options. It would greatly cut down how long pikas needed to spend out in the cold, Speakman says.
The researchers caught pikas scarfing scat on video. DNA from the animals’ stomach contents confirmed that this diet is common. Whether dining on dung has downsides remains to be seen. But clearly, not being too picky pays off for pikas.