Predators build predictive models with echolocation to track prey

On November 30th, during the 181st Meeting of the Acoustical Society of America, Angeles Salles of Johns Hopkins University will discuss how bats use echolocation to find prey and track and predict its trajectory.

Bats use echolocation to create echo snapshots of their environment, capturing it in discrete stages. They generate the sounds used for echolocation from their larynx or by clicking their tongues and process the echoes that return after sending out those noises. These noises are typically ultrasonic, so humans are unable to hear them.

Unlike predators that rely on visual cues, this allows bats to hunt in total darkness. Because they cannot track prey continuously as a predator would visually, the echo snapshots provide staggered sensory information on the prey as it moves through space. The bat's brain creates a predictive model that allows it to extrapolate the prey's trajectory based on its movement through the snapshots it receives.

"We think this is an innate capability, such as humans can predict where a ball will land when it is tossed at them. Once a bat has located a target, it uses the acoustic information to calculate the speed of the prey and anticipate where it will be next," said Salles.

Echolocating bats will amalgamate echos from prey to determine their size, distance, shape, and density, ultimately helping them identify what they are tracking and decide if they will pursue it.

"Prey with erratic flight maneuvers and clutter in the environment does lead to an accumulation of errors in their prediction. If the target does not appear where the bat expects it to, they will start searching again," said Salles.