Based on the vampire bat’s diet, Welch and his team hypothesized that the mammals would use the amino acids from blood to fuel their running and flying. To test the hypothesis, the scientists ...

A version of this article appears in print on Nov. 19, 2024, Section D, Page 2 of the New York edition with the headline: Vampire Bat Workout: Sure, They Want Your Blood.

But every good rule deserves an exception. Vampire bats, for example, feed only on blood: an energy drink low in lipids and carbohydrates, and rich in protein.