The Great Moth-Bat Showdown: When Moths Have Found Their Voice and Have Started Yelling at Bats

By: Victoria Elguea Garcia

Has your pizza ever tried to distract you by yelling? If it has, then you have experienced what it is like to be a bat hunting for moths. Bats are some of the best night-time hunters in the world; they have developed a highly precise hunting technique called echolocation. During echolocation, bats produce a series of ‘clicks’ and ‘buzzes’, these sounds echo off of the objects in their surroundings. The returning sounds allow them to visualize the world around them. In order to survive, some of the animals they hunt - commonly known as prey - have had to develop countermeasures. Some species of moths do this by producing sounds of their own, these are designed to interfere with the bats ability to echolocate. Yohami Fernández Delgado and her colleagues at Wake Forest University in the U.S., hoped to determine the difference between defensive sounds and communicative sounds in moths. As well as to determine how bats attempt to overcome this added challenge.

To answer these questions, the research team hung live moths in a large enclosure.Every night, they released a wild bat in the enclosure; three different bats were used over the course of the experiment. While the bats were hunting they played recordings of moth sounds, these sounds were repeated at three different time intervals. This variety allowed the researchers to determine if it was the sounds themselves or the frequency that caused them to interfere with the bat’s hunting capacities. The researchers suspected that it was the frequency of the moth sounds that differentiated between communication and defence sounds. They recorded all of the hunting attempts so that they could analyze the bat’s echolocation calls and hunt success. Previous studies have found that bats increase the length and intricacy of their echolocation sounds in response to complicated environments. The team hoped that these recordings would allow them to confirm their theory that bats would increase echolocation call length and complexity in order to counteract the moth’s defence attempts.

The researchers found that the interval between repetition of the moth sounds did not have an affect on hunt success. This rules out the theory that moth communication sounds occur less frequently than defensive sounds. The researchers state that further research would be required to determine differences in moth sounds. They did determine that in response to moth sounds, bats increased the length of the last segment of their call. The researchers suggest that the increased length allows the bats to gain more information when their echolocation is being interfered with. Interestingly, they found that bats did not make their calls more complex upon hearing the moth sounds. This suggests that the increased length of the call is enough to counteract the moth’s interference.

The bats’ ability to thwart interference from moths gives scientists some invaluable insight into bat and moth biology. These findings prove that not only can bats change their calls in response to interference, but also that they are able to hear and recognize this strategy. Bat echolocation is interesting enough from a biological perspective, but technologically it provides more knowledge than we can ever know. Most of the technology we use to locate planes and ships is based on technology similar to echolocation. Increasing our understanding of echolocation can provide us with new ideas to improve these kinds of technology. Most of all, this article shows us that although our vegetables aren’t always yummy, at least they don’t try to argue their way out of being on the dinner plate.

Fernández Delgado, Y., Dowdy, N. J., Conner, W. E. (2022) High duty cycle moth sounds jam bat echolocation: bats counter with compensatory changes in buzz duration. Journal of Experimental Biology. 225 (18), jeb244187.

Image by: Victoria Elguea Garcia