Pikas munch moss to survive warmer climate

Pikas, the adorably tubby mammals that favor cool mountain habitats, may be able to adapt to climate change by eating a lot of moss, a new study suggests.

American pikas are an oft-cited example of animals threatened by climate change because they’re particularly picky about temperature. Usually, they live in cold, high-elevation areas. But scientists know of at least one exception: A population of pikas happily makes its home in the Pacific Northwest’s Columbia River Gorge, even though the area is near sea level and warmer than their usual habitat.

It wasn’t clear how the animals could “persist in this seemingly unsuitable climate,” researchers write in the Journal of Mammalogy. So the team watched 20 pikas at two sites in the gorge for 220 hours, taking note of what the animals ate and how much they consumed. The researchers also surveyed the plant life in the area and analyzed the nutrient content of the pikas’ meals.

The pikas ate 31 plant species, including lichens, thimbleberry shrubs, and Douglas fir needles. But their favorite food was moss: It made up about 60 percent of their diet.

That’s a bit surprising because moss isn’t very nutritious. It’s low in nitrogen, and 70 to 80 percent of it is fiber. “Some fiber is good, but this is almost all fiber,” said co-author Jo Varner of the University of Utah in a press release. “It’s a bit like eating paper.”

The pikas may recover some nutrients by producing pellets, called caecal pellets, that contain a higher concentration of nitrogen, then eating them. The nitrogen content of the pikas’ pellets was about 6 percent, compared to less than 1 percent in moss.

And while eating the nutritional equivalent of paper might not sound appetizing, pikas may prefer moss simply because there’s so much of it growing in the area. With such an abundant supply, the animals don’t have to put as much energy into building up food stores for the winter. And that means less time spent foraging for plants during hot summer days.

The study suggests that the pika can adapt to a warmer habitat by “incorporating unusual food sources into its diet,” the team writes. So one way to protect pikas from the effects of climate change might be to keep people from collecting or trampling mosses. Roberta Kwok | 19 December 2013

Source: Varner, J. and M.D. Dearing. 2013. Dietary plasticity in pikas as a strategy for atypical resource landscapes. Journal of Mammalogy doi: 10.1644/13-MAMM-A-099.1.

Image © Randimal | Shutterstock

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