Primitive form of navigation found in fruit bats
Old World fruit bats can’t use sound to navigate, an ability known as echolocation that’s found in all other bats. At least that’s what scientists thought. But a new study reveals that these bats can indeed echolocate; instead of generating sounds with their larynx, they use their wings. By setting up a series of flying tasks, scientists were able to determine if the fruit bat’s sounds, faint clicks synced with their wing beats, were useful in generating sonic maps to navigate in the dark. In one experiment, the animals were trained to discriminate between two large surfaces, a reflective board and a piece of fabric, and land on the board. When the lights were turned off, the bats completed the task and landed on the board—although rather clumsily—70% of the time. The scientists also made the bats fly through a dark room strung with a maze of wires. The fruit bats failed at this task, repeatedly crashing into the wires—which were 100 times thicker than those that other bat species were able to detect and avoid, the team reports online today in Current Biology. The fruit bats’ shaky performance on these night vision tasks indicates that although they do possess echolocation, theirs is a more rudimentary version than that of other species, suggesting that echolocation may have evolved and been lost many times throughout its evolution in bats.