ScienceShot: Eating Moss to Survive

Jo Varner

ScienceShot: Eating Moss to Survive

The pika does not ask for much. Something green to nibble on, a hole to hide from hawks, and cool air to breathe. Especially that last one, because the chubby gopher-sized relative of rabbits overheats and dies in temperatures greater than 26°C. Thanks to global warming, the pika has disappeared from many of its natural mountain habitats in the U.S. Pacific Northwest, and those that remain tend to migrate to higher elevations. But pockets of pikas are bucking that trend by living stably in shady talus slopes, the accumulated rockfall debris at the base of mountains. The mystery is that there is very little to nibble on down there. Now, a study of the diet of these lowland pikas reveals the food that allows them to eke out a living: moss. Very few herbivores bother with moss because it is mostly rough fiber with not much more nutrition than paper. But the pikas in Oregon’s Columbia River Gorge rely on it for 60% of their diet, the team reports today in the Journal of Mammalogy. To squeeze out every bit of sustenance, they poop the moss out in a form called caecal, which concentrates protein from the plant sixfold. Then they eat it and redigest it. Mystery solved.

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*Correction, 17 December, 6:20 p.m.: Pikas rely on moss for 60% of their diet, not 80% of their diet, as was previously reported.

*Correction, 18 December, 11:50 a.m.: The art has been replaced; the previous art depicted lichen, rather than moss.