New research, complete with night-vision video recordings, helps elucidate how bats actually fly to find their prey. The work was published online on January 28, 2015 in the open-access journal PLOS Biology. The article is titled “A Sensory-Motor Control Model of Animal Flight Explains Why Bats Fly Differently in Light Versus Dark.” Every night a bat puts in 600-700 kilometers of airtime. Flying low, the animals catch insects at speeds of approximately 40 meters per second. At night, the bat uses its hearing to navigate its way to prey. Bats catch insects continuously using echolocation, an advanced navigation system. The bat emits ultrasonic waves with very high frequencies. Its calls are pitched at 20-100 kilohertz, a frequency that is too high-pitched for humans to hear naturally. Their sounds are reflected in the environment, hitting various objects and returning to the bat as echoes. The echo signals enable the bat to form a mental map of its surroundings. According to Dr. Nadav Bar, an Associate Professor at the Norwegian University of Science and Technology’s (NTNU's) Department of Chemical Engineering who has recently researched bats, “You can compare echolocation to using a flash in a dark room. The flash hits various objects in the room that light up and are reflected back to the eye of the observer. The bat uses sound in the same way to get an overview of the environment, but the potential sources of error are far greater when using sound.” When bats on rare occasions fly during the day, they use their vision to navigate and fly in a straight line to their destination. Night-time flights are more elaborate than daytime ones. Bats continuously rise and dip in curved flight trajectories, using large movements to propel themselves.
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