Science & Technology

Experimental broadcast of White Water River Noise drives away bats and birds

Dr. Dylan Gomez led a team that deployed speaker arrays in early spring to recreate the noise of rapid rivers before most birds and bats use the highlands (5,000-7,000 feet) of the mountains. have started. Credit: Dr. CoryToth

Many may think that walking in the woods is a quiet and peaceful escape from their noisy urban life, but we often believe in some natural environments. I don’t think about how noisy it can be. To relax and meditate, we use the soothing sounds of nature in our daily lives, but the thunder and throbbing waves of mountain rivers can be a way of communicating with animals and where they live. It seems that it has changed over the years.New experimental study published in the journal Nature Communications Birds and bats have often been found to avoid the noisy habitats of large torrent rivers.

Dr. Dylan Gomes, a recent PhD from Boise State University and lead author of the treatise, summarizes the purpose of this study as follows: The aim was to test the hypothesis that intense natural noise can shape the distribution and behavior of animals by experimentally broadcasting large-scale torrent river noise. In fact, scientists have literally transported large amounts of gear to roadless terrain to place solar-powered speaker arrays in half of the 60 locations in the Pioneer Mountains of Idaho, and birds during the two summers. And bat populations needed to be monitored.

Speaker arrays were placed along the banks of the river, filling each bubbling stream with a torrent river auditory experience. The team used an experimental approach to both realistically reproduce the river noise and shift the frequency upwards to understand how the noise caused changes in the number of animals. Broadcasted.

“A common hypothesis as to why many animals avoid noise is called masking. Masking occurs when the frequency of noise (what is perceived as pitch) overlaps a biological signal or queue. By broadcasting noise of various frequencies, we wanted to evaluate the role that masking of important sounds such as bird chirping plays in avoiding noisy places, “said Boishi, the lead author of the study. Dr. Jesse Barber of State University said. Scientists have predicted that background noise and song frequency overlap will reduce birds until the acoustic environment is about as large as a highway, at which point prey and prey cannot be heard. Discovered that the power of can be more important.

It’s clearly important to understand how noise drives animals out of a otherwise good habitat, but what about animals staying behind? To study the foraging of birds that naturally stayed in noisy areas, the authors set up hundreds of clay caterpillar decoys throughout their research site. By carefully examining the types of predator traces left on the clay, scientists found that the louder the noise, the less foraging the birds. This means that even after controlling the fact that the number of birds found in noisy areas is low, birds are less efficient at visually locating these quiet decoy caterpillars in the presence of noise. .. This is the same difficulty people experience when trying to listen to a friend when a muted TV is on, and divides our attention.

To understand how the bats that remained in the noisy area progressed, the team unfolded and solved two foraging puzzles. The first was “Roboga,” which seduces bats with its insect-like flapping wings. The second was a speaker that played a “mixtape” of cricket and grasshopper calls and insect walking sounds. After nearly 150 nights of data collection, scientists have discovered that as the world grows, some bats switch from hearing their prey to using echolocation. Dr. Gomez said, “This behavioral switch may be caused by the barking and footsteps of the prey being hidden by the noise of the river, and this kind of problem-solving is a torrent of raging some bats. May explain why they stay near the river turmoil. “

Putting all these factors together, the author better understands how animals deal with human-generated noise by studying how animals react to the noise sources they have faced throughout their evolutionary history. Claim to be understandable. Dr. Clinton Francis of California Polytechnic State University and co-principal investigator of the study said: The spatial and temporal footprint of anthropogenic noise is much greater than in a noisy natural environment. “

Reference: May 24, 2021 Nature Communications..
DOI: 10.1038 / s41467-021-22390-y

Other co-authors of this paper include former postdoctoral researcher Dr. Cory Toth and current master’s student Hunter Cole, who are members of the Barber Institute at Boise State University. This work was carried out on land funded by the National Science Foundation and owned and managed by the Lava Lake Ranch.

Experimental broadcast of White Water River Noise drives away bats and birds Experimental broadcast of White Water River Noise drives away bats and birds

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