Scientists at the San Diego Zoo’s Institute for Conservation Research recently did something unusual with 24 endangered mountain yellow-legged frogs. They put them in refrigerators! It may sound like a punchline, but the scientists refrigerated the frogs to encourage them to breed. “The cold temperatures mimic high-elevation winter conditions that cause the frogs to hibernate. Typically, mountain yellow-legged frogs display mating behaviors after emerging from hibernation,” said a statement from the zoo.

The frogs went into the refrigerators on January 1, 2010. The scientists are planning to move them to a breeding area in the lab at the beginning of April.

Read more about the frosty frogs on the NatGeo News Watch blog.

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Watch a video of leopard frogs on National Geographic Kids.

Photograph by Adam Backlin, U.S. Geological Survey