Winter on the Qinghai-Tibetan Plateau is unfriendly to pikas. Temperatures throughout the barren, windy highlands routinely dip beneath –30° Celsius, and the grass that usually sustains the rabbitlike mammals turns into dry and brittle. It could appear the proper time for these critters to hibernate, or subsist on shops of grass in burrows to remain heat, just like the North American pika.
As an alternative, plateau pika (Ochotona curzoniae) proceed foraging in winter, however scale back their metabolism by about 30 p.c to preserve power, researchers report July 19 within the Proceedings of the Nationwide Academy of Sciences. Some pikas additionally resort to uncommon rations: yak poop.
Digicam knowledge from 4 websites confirmed that pikas usually courageous the chilly to forage. “Clearly they’re doing one thing fancy with their metabolism that’s not hibernation,” says John Speakman, an ecophysiologist on the College of Aberdeen in Scotland.
Speakman and colleagues measured every day power expenditure of 156 plateau pikas in summer time and winter, and implanted 27 animals with temperature sensors. Whereas many nonhibernating animals maintain heat in winter through the use of extra power, these pikas did the alternative (SN: 1/22/14). On common, pikas decreased their metabolism by 29.7 p.c, partly by cooling their our bodies a pair levels in a single day. The animals had been additionally much less energetic, relative to summertime ranges.
However at websites with yaks, pikas had been extra plentiful however even much less energetic. That puzzled the researchers “till we discovered a kind of half-eaten yak turd in one of many burrows,” Speakman says. Consuming excrement may cause illness. However with few choices, yak poop could possibly be an plentiful, simply digestible meal that “massively reduces the period of time [pikas] must spend on the floor,” he says.
The researchers caught pikas scarfing scat on video, and DNA proof from abdomen contents solidified that this conduct is frequent. Whether or not eating on dung has downsides stays to be seen, however clearly, not being too choosy pays off for pika.
The place pika and yak overlap, the rabbitlike mammals (proven) discover an plentiful and simply digestible source of meals in yak feces. Consuming the excrement helps pikas, which don’t hibernate, survive throughout onerous winter months on the Qinghai-Tibetan Plateau.