Bats can navigate both visually and acoustically, by sending out sound waves and listening for echoes bouncing off objects—including prey. Bat vision is generally known to be sharpest in dim light, and to get worse the brighter it gets.

(Related: "'Whispering' Bat Evolved to Trick Prey.")

For the new study, scientists set up an obstacle course near an abandoned mine in Ontario, Canada, where little brown bats often gather.

The team manipulated three types of light conditions—dark, dim, and bright—and observed how little brown bats flying through the course behaved. The results showed that bats primarily relied on their vision to navigate the well-illuminated course—even though their reliance on vision made them