evltnDespite the destruction of the Great Plains, a native species of mouse has evolved to thrive in the new ecosystems humans have created.

1. Mice Where They Shouldn’t Be

In January, the Indiana farm field was little more than a harsh, barren stretch of dirt. An icy wind blew without restraint over rutted soil, soy stubble and stripped ears of corn. Jacob Berl crossed the field in a pickup truck, stopping at a small wooden box buried in the soil, only its top showing. He popped its lid with a crowbar, reached in and pulled out a prairie deer mouse (Peromyscus maniculatus bairdii)—a unlikely creature surviving in a wasteland.

The size of a small Roma tomato, she had a russet-colored back with a darker streak down her spine, and a white belly like a deer. A few of her three-week-old babies crawled around in the box. The shock of being picked up caused the mother to defecate. Berl grabbed a plastic tube and let the fecal pellets tumble in so he could analyze them in his lab.

From the type of carbon atoms in the pellets, Berl could tell whether she had been eating the small grass and wildflower seeds that make up a prairie deer mouse’s typical diet, or if she had been eating an entirely new diet of corn and soy provided by humans.

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