![]() Lohr says you'd expect the resident birds to adapt their songs. "That should have obvious implications for the acoustics of the habitat." "In one sense, I kind of think, why hadn't anyone thought of doing this before?" he says, noting that human activity has resulted in an explosive growth in deer populations. When deer are browsing, the sound actually has higher fidelity as it moves through environment."īernard Lohr, a biologist at the University of Maryland, Baltimore County, who did not work on the study, says this is an intriguing finding. You don't have as many sounds bouncing off of leaves and sticks and things like that. "When deer were browsing, we actually found that the sound was clearer," Gall says, "and that's probably because there was less vegetation in the way. But the structure of a sound changed a lot when it was propagated through a lush, green understory that the deer hadn't snacked on. The results, published in the journal PLOS One, show that the overall loudness didn't change much - which didn't really surprise the researchers, since they were measuring only over short distances of 36 feet or less. "We wanted to have sort of a very broad palette of sounds to look at." They checked sounds that they sent through the lowest level of the forest, in the middle-level of the forest and at angles going from the ground upward. "All of these things are found in different kinds of animal sounds," Gall says. Rather than using specific bird calls, the researchers played a series of pure tones, white noise and trills. They broadcast different sounds and checked to see how those sounds changed after traveling through each environment. Gall and two students, Timothy Boycott and Jingyi Gao, set up audio equipment around these areas. The other area was marked off but left open so that deer could enter and graze. One area was fenced off in a way that kept out the deer. To see how deer might change what other animals hear, she decided to do some experiments in a couple of forested areas that her colleagues had set up for their deer studies. She also had previously studied how human-generated noise can impact wildlife communication. Gall already knew that sound travels differently through open fields than through the woods. ![]() She got intrigued by the possibility that deer might affect the soundscape after talking with a couple of colleagues who were studying how browsing deer could transform a forest ecosystem by munching through the entire lower level of leafy plants. ![]() "It's much lusher when there are fewer deer around, and so that's a big change in the structure of the environment." "The deer are very, very over abundant," says Megan Gall, an ecologist at Vassar College who studies how the environment shapes animals' senses. are likely changing the acoustics of their forests by eating up bushes, small trees and other leafy plants that normally would affect the transmission of natural sounds such as bird calls. A white-tailed deer keeps its ears open while grazing in South Hero, Vt. ![]()
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