Scientists have unearthed new coping mechanisms used by certain mammals to overcome human-created noise levels when hunting down their prey.

A recent study on the preying habits of fringe-lipped bats in the context of rising disturbances from human-induced noise revealed that the bats use echolocation as a second sense to pinpoint the prey when the mating calls of tungara frogs are overlapped by other noises.

The study, which was published in the Sept. 16 issue of Science, reveals what a bat will be doing when road noises block their perception of frogs, identified by the mating calls they make.

Wouter Halfwerk, a professor at VU University in Amsterdam, hailed the experiment and said it showed how animals are adapting to increased noise levels by energizing other senses.

According to experts, the action of bats is comparable to the way people speak to one another in hushed tones in a noisy party: by tuning out the unwanted noise.

By tracking the reflecting signals from high-frequency sounds, the bats' echolocation ability lands them to a new sensory mode for assessing the environment perfectly.

Found mostly in South and Central America, fringe-lipped bats prey upon male tungara frogs by acting on their mating calls and hunting them down with perfect precision. The mating calls initiate the flight of the bats from their perch.

Lead author Dylan Gomes, who conducted the research at Panama's Smithsonian Tropical Research Institute (STRI), said the impact of noise on bats is a new area of study.

Previous studies have been focused more on the effects of human-generated noise on birds and whales. The new study showed how anthropogenic noise has been changing the way animals process environmental information.

It affirms that animals that are able to shift their sensory mechanisms in noisy environments are more successful as predators.

Use Of Robotic Frogs

In the study, the researchers used two robotic frogs that accurately mimicked túngara frogs in terms of mating calls and vocal sac expansion for attracting the bats. One frog emitted the mating call while the other played the mating call and expanded its vocal sac.

It was found that, despite a masking noise, the bats were faster in attacking the robotic frog that emitted both signals. The experiment proved that bats adapt to noise by using their other senses to increase their echolocation power.

The findings are a pointer for further research on how animals adapt to anthropogenic noise with implications for sensory ecology and species interactions.

Photo: Gerwin Sturm | Flickr

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