A nectar-feeding bat that was thought to eat insects in passing has been discovered to target its moving prey¹ with stealth（秘密） precision, according to new research by a scientist at Queen Mary University of London. The researchers uncovered for the first time that the Pallas long-tongued bat use echolocation -- a complex physical trait that involves the production, reception and auditory processing of ultrasonic² pulses for detecting unseen obstacles or tracking down prey. Most bats produce a rapid sequence of echolocation pulses to attack their prey and many insects have developed 'bat-detecting ears' in return to avoid being caught.

 

A genetic³ analysis of the bat's food waste showed that it consumes a type of moth⁴ that should be sensitive to being captured. To determine how the bats approach their insect prey, the scientists used sound recordings⁵ and infrared⁶ video to monitor the bats detecting and approaching tethered mealworms.

 

The results, published in the journal Functional⁷ Ecology, show that the bat's echolocation calls were high in frequency but low in intensity⁸ making it difficult for the insect to detect the imminent⁹ danger.

 

"When we compared the bats' echolocation calls to the moths¹⁰' auditory abilities, we found that the low intensity echolocation calls were not loud enough to trigger the auditory neurons of moths with ears," explains Dr Elizabeth Clare from Queen Mary's School of Biological and Chemical Sciences.

 

"In effect, the echolocation of Pallas's long-tongued bats is too quiet for the moths to hear and allows them to sneak¹¹ up on their target using a stealth tactic¹²."

 

The discovery means that the European barbastelle bat (Barbastella barbastellus) is no longer the only bat to use stealth echolocation to sneak up on moths.

 

Dr Clare added: "Our analysis suggests there might be more bats than previously¹³ thought that benefit from this stealthy approach that prevents prey from escaping by listening for bats."

 

The Pallas long-tongues bats (Glossophaga soricina) are an important pollinator in Central and South America and belong to a group of bats that are often called 'whispering bats' because many emit relatively¹⁴ quiet echolocation calls to forage¹⁵ within dense¹⁶ vegetation.

 

The research involved scientists from The University of Bristol; The Max Planck Institute (Germany); The University of Maryland (USA); The University of Massachusetts (USA); Western University (Canada), and The University of Guelph (Canada).

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