Often when a dog is trying to determine the exact origin of a noise, they will tilt their head in an utterly adorable way. This physical movement can help to enhance signals from other senses, such as hearing and sight. Yet it is not only dogs who perform such "head waggles", as humans and cats are known to do it too. Now, it turns out that bats also do something similar when honing in on their prey.
In a fairly bizarre experiment, researchers managed to train three big brown bats (Eptesicus fuscus) to rest on a platform while tracking prey, which took the form of mealworms attached via fishing line to a miniature bug zipline. As if that wasn’t weird enough, they then (humanely) glued tiny reflectors to the heads and ears of the bats like some low-budget 70s sci-fi show, allowing the researchers to track the bats' head movements while they filmed them "hunting" the insects that zipped by.
By then pairing the slowed-down footage with recordings of the bats as they used their sonar to track the high-flying worms, the scientists were able to determine how the mammals use their head cocks and ear waggles to hone in on their prey. As the mealworms approached, the bats altered the frequency of their sonar pulses as well as the length of their vocalizations. The study, published in PLOS Biology, found that the bats also tilted their heads to change the relative elevation of their ears and to alter the distance between the tips of their ears.
The bats do this, they discovered, at the same time as when the insects they are hunting move suddenly or change direction. When coupled with the bats' sonar, the researchers suspect that these head waggles help them to keep track of exactly where their prey is, allowing them to accurately catch their prey before they get away. "By studying these movements," explains co-author Cynthia F. Mossthe in a statement, "we as humans can get insight into how movement helps animals sense their environment."
It's possible that by understanding how these animals coordinate their movements and senses, it could help engineers create better robotic sensory systems.
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