This ability comes from the bats' advanced hearing - their ears are more sensitive to different frequencies, allowing them to pick out the echoes even when they are emitting calls.
Intermittent-calling bats' reactions are slowed as they must wait for an echo response. Continuous callers, on the other hand, can track their prey's every move.
So Dr Fenton thought that bats that are able to differentiate between frequencies in this way might be particularly adept at detecting flying insects, such as moths.
To test the theory, Dr Fenton's team created an accurate simulation of a fluttering insect and played recorded bat calls near it.
The reflected calls had an oscillating pitch, like a wailing siren, whereas stationary objects including leaves and branches produced single-toned echoes.
Dr Fenton was convinced that the bats would be able to tell the difference between these two types of echoes. To prove it, he and his team tested "Robo-moth" in the field.
Rhinolophid bats are very efficient at catching fluttering targets
During their research in Taiwan, the team found almost all of the approaches to the robotic moth were made by continuous-calling bats, including lesser horseshoe bats and great roundleaf bats.
"People had predicted that the bats should be able to detect fluttering targets in clutter... and this is an experimental demonstration that they do just that," said Dr Fenton.
There were however four species of bat that were not continuous callers that still approached Robo-moth. Dr Fenton believes these bats may be "intermediate species" - an evolutionary link between intermittent and continuous callers.
He suggests that bats could have evolved the radar-like echolocation strategy to improve their chances of catching more nutritious insect prey.
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