Sunday, October 17

Human Noise Affects Animal Behavior, Studies Show | Animal behavior


Working from home during Covid-19 has brought noise pollution close to home, whether your partner is making calls within earshot or grinding coffee during your Zoom interview. Now, research suggests that the animal kingdom is also disturbed by noise from humans and our devices.

As humans proliferate, we have penetrated deeper into wildlife habitats, creating a widespread increase in ambient sound that not only directly affects animals’ ability to hear, but also to communicate. Emerging research suggests that noise pollution, caused, for example, by traffic, interferes with animal behavior, including cognition and mating.

In an attempt to capture the impact of traffic sounds on cognitive performance, the researchers gave adult zebra finches, a species of tiny songbirds native to Australia, a series of foraging tasks.

The birds were either in a relatively quiet laboratory environment or treated with traffic noises designed to simulate a series of cars passing 20 to 30 meters away.

To test inhibitory control, a useful ability to maintain the attention required to solve a problem, songbirds were given access to a horizontally placed transparent cylinder with food inside. The researchers evaluated whether the birds would succumb to their intuitive response to reach or take the most efficient route around the side that was left open.

The next task was to open the lid to access the food. This was designed to measure motor skills and object manipulation, which are critical to foraging. After that, the birds went on to associative color learning, where their ability to discriminate between different colored caps was tested to determine which one contained the food reward. The researchers also tested spatial memory, which is crucial for remembering the location of food sources, territorial boundaries, and potential mates.

Finally, they tested the birds’ ability to learn from each other. Some “demonstrator” birds learned to pull knots to access food hidden within the wooden blocks, and others were judged on their ability to emulate the task.

All tasks, apart from learning color association, were negatively affected by traffic noise, according to the researchers. wrote in the journal Proceedings of the Royal Society B.

“We weren’t really sure we would see such a strong effect,” said study author Christopher Templeton, an assistant professor at the University of the Pacific, Oregon, USA.

“These are birds that… live in large colonies, they are all talking all the time making a big fuss. So seeing that simply hearing a car pass is enough to prevent them from performing in these tests is quite surprising in some respects. “

A seperation study, published in the journal Behavioral Ecology, analyzed how female Mediterranean field crickets, Gryllus bimaculatus ̧ make mating decisions in different acoustic conditions.

Males attract females by singing a courtship song by rubbing their wings.

“In this species, specifically, we know that male courtship song is related to immunocompetence, so [the females] they know that if they have a particular high-quality song, they are better at surviving disease, ”explained lead author Dr Adam Bent of the University of Cambridge, who conducted the study as part of his Ph.D. Anglia Ruskin University.

To test the impact of different noise conditions, the researchers paired female crickets with male crickets whose wings had been clipped to silence their ability to sing. The crickets were then allowed to interact under ambient noise conditions or man-made noise conditions or traffic noise conditions.

Then, an artificial courtship song was played as the males attempted to woo the females.

Females tend to look for males of multiple quality, so the faster they can mate, the better it will be, so they can go ahead and find another mate. The more pairs they have, the greater the offspring and the greater the probability that the offspring will survive.

In the context of ambient noise, females mounted males much earlier and more frequently when paired with a high-quality courtship song, the researchers found.

But the high-quality song did not offer any benefit in the white noise and traffic noise conditions. “The data … show that females are unable to detect subtle differences in song, and that means they cannot show any difference between males performing a high-quality song and males performing a low-quality song.” said Bent.

“On an individual level, this will have knock-on effects, potentially, for their offspring and the viability of their offspring. But at the population level, mate choices are a really powerful mechanism of sexual selection and sexual selection drives evolution, ”he suggested.

“So by having mate choices interrupted in this way, it could vastly change the course of the evolution of the species.”


www.theguardian.com

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