Good Vibrations: Katydids communicate when the wind is calm

Featured Image Caption: The wind produces vibrations in plants that are similar to the vibrations that katydids use to communicate. To reduce this problem, katydids communicate when the wind is calmest  (Source: via pxfuel).

Reference: Velilla, E., Muñoz, M., Quiroga, N., Symes, L., ter Hofstede, H. M., Page, R. A., Simon, R., Ellers, J., Halfwerk, W. (2020). Gone with the wind: Is signal timing in a neotropical katydid an adaptive response to variation in wind-induced vibratory noise? 74, 59. https://doi.org/10.1007/s00265-020-02842-z

I Can’t Hear You Over the Wind!

Have you ever called someone on the phone outside when it is really windy and as a result, the person on the other end has a hard time understanding you? The wind, in this sense, can be disruptive to our conversations. To solve this problem, we can just take our conversation inside, away from the wind. A blustery day does not have to ruin our chats with friends and family.

The wind shakes leaves and branches and sends vibrations throughout the plant (Source: SoCali via Pixabay).

Many animals have to deal with noise created by the wind too. However, instead of interrupting conversations that occur as sound, the wind is very disruptive for animals that communicate using vibrations on plants. We use vibrations to communicate sometimes too, such as when our phone vibrates to let us know that someone has sent us a message and would like to communicate. Hundreds of thousands of animals use vibrations to communicate with other individuals of the same species.

Leaves and branches blowing in the wind can create vibrations that mimic and mask those produced by animals, especially insects. Animals can adapt behaviorally to these conditions either by changing the features of the vibrations or by communicating when the wind is calmer. Katydids, an insect in the same order as grasshoppers and crickets, must adapt to vibrations created by the wind to effectively communicate.

Katydid Communication

Estefania Velilla – a Ph.D. student at Vrije Universiteit Amsterdam in the Netherlands – and her colleagues wanted to determine how katydids (Copiphora brevirostris) deal with vibrations caused by the wind. In order to produce vibrations, male katydids shake their abdomens while standing on a plant branch. These vibrations travel through the plant – and sometimes nearby plants – to reach other katydids. Katydids use vibrations to send information to potential mates and competitors about their quality and location. The vibrations caused by the wind can interrupt or coverup the vibrations that katydids use to communicate. If katydid vibrations are disrupted, mating can become increasingly difficult, potentially leading to declines in the population.

Male katydids produce vibrations to communicate their location and quality to other katydids by standing on a branch and shaking their abdomens (Source: Caramosca via Flickr)

In order to determine if the features and timing of plant vibrations from wind and katydids overlapped, the researchers recorded the vibrations of male katydids in the lab without wind as well as plant vibrations from natural wind in the field and artificial wind in the lab. The researchers also performed a lab experiment using artificial wind at four different speeds and recorded the number of vibrations males produced during exposure to each wind speed.

The vibrations caused by wind and katydids were very similar in feature, which suggests that the wind can mask the signals that katydids are sending to each other. The wind blew at the greatest speeds between 10:00 PM and 2:00 AM. Male katydids produced the majority of their vibrations between 2:00 AM and 5:00 AM once the wind was the slowest. During the wind experiment, male katydids produced the most vibrations when the wind was the calmest and the least during the strongest winds.

Can you hear me now?

Even though katydids cannot go inside of a building or easily find a less windy spot like we can, they can still make sure that their message is received by other katydids. Rather than changing the features of their vibrations, males of this species change the timing of their vibrations so that the signals are not lost in the wind. Katydids produce most of their vibrations in the early morning hours after the winds are the calmest while many of us are still fast asleep. It can take a lot of energy for a katydid to change the features of the vibrations but changing the timing of the vibrations conserves more energy. As a result, katydids can use reserved energy in the search for food and mates.

Wind and katydids produce vibrations that are similar in feature, so katydids communicate when the wind is the calmest (Source: Ian Morton via Flickr).

Studies like this one are important because ecologists hypothesize that the majority of animals use vibrations in some way and yet we know very little about how vibrational noise, such as wind, affects the ability of these animals to communicate effectively. In addition to the wind, noisy vibrations can be caused by rain, other animals, and especially humans. We produce a lot of vibrations, particularly in cities where noise from transportation, industry, and construction is continuous. Vibrations can inform animals of the presence of predators, competitors, and mates but animal populations can decline if this information is not accessible. The study of animals that use vibrations for communication is a relatively new and exciting field of research that will continue to unveil the diversity of animal life and may provide a new perspective on how human presence can affect animals.

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Brandi Pessman

I am a first-year Ph.D. student at the University of Nebraska-Lincoln in the School of Biological Sciences. Growing up on a farm in a small town in Illinois, I developed an early love for animals and a fascination with their behaviors. When I was younger, however, it never crossed my mind that I would be using spiders to investigate how human presence affects animal behavior, but I am loving every second of it. Studying the behaviors of animals can tell us a lot about the role that we play in their survival (or death), which is becoming increasingly important as human populations continue to grow. When I am not studying spiders, I enjoy playing with my cat or being outdoors!

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