Biological Effects of Noise on Wildlife
June 6, 2009
Acoustic Ecology Institute
Research on this topic has taken place for years, quite a bit below the surface of public awareness. Bernie Krause has written about several striking examples; here are some excerpts (see full essay linked below).
“Many types of frogs and insects vocalize together in a given habitat so that no one individual stands out among the many. This chorus creates a protectively expansive audio performance inhibiting predators from locating any single place from which sound emanates. The synchronized frog voices originate from so many places at once that they appear to be coming from everywhere. However, when the coherent patterns are upset by the sound of a jet plane as it flies within range of the pond, the special frog biophony is broken. In an attempt to reestablish the unified rhythm and chorus, individual frogs momentarily stand out giving predators like coyotes or owls perfect opportunities to snag a meal”
“Because of the noise introduced into their environment by cruise boats traveling in Glacier Bay, humpback whales have been observed trying to swim away and hide from the noise, ducking behind spits of land or large blocks of ice that had broken off glaciers apparently in an effort to get into quieter “shadow” zones. Where once there were many, in recent years, fewer and fewer whales have been seen in the Bay. Along with other factors such as the special manner in which certain vessel noise may be amplified by the geological features of the Bay contour, it is believed by some biologists that human-induced noise is a major contributing ingredient to the falling numbers. ”
“And very recently, Scott Creel, a biologist at Montana State Univ., along with a number of his colleagues, wrote a paper that tied (gluco-corticoid) enzyme stress levels in elk and wolves to the proximity of snowmobiles and the noise they create in relation to the wild populations in Yellowstone and Voyageurs Parks. With wolves, over the period of time that snowmobile traffic increased 25%, stress enzyme levels increased by 28%. Conversely, within Voyageurs Park, a 37% decline in snow mobile traffic between 1998 and 2000 correlated to a an exact drop of the same percentage in stress enzyme levels over the same period. These figures are found to be comparable in elk. ” See press report on this study: [GO THERE]
Loss of Natural Soundscape – A paper given to the World Affairs Council in 2001 by Bernie Krause, Ph.D. The above examples of animal responses to noise are included in this essay.”Through my field work, I discovered that in undisturbed natural environments, creatures vocalize in relationship to one another very much like instruments in an orchestra. On land, in particular, this delicate acoustic fabric is almost as well-defined as the notes on a page of music when examined graphically in the form of what we sometimes call voice prints. For instance, in healthy habitats, certain insects occupy one sonic zone of the creature bandwidth, while birds, mammals, and amphibians occupy others not yet taken and where there is no competition.
This system has evolved in a manner so that each voice can be heard distinctly and each creature can thrive as much through its iteration as any other aspect of its being. The same type of event also generally occurs within marine environments. This biophony, or creature choir, serves as a vital gauge of a habitat’s health. But it also conveys data about its age, its level of stress, and can provide us with an abundance of other valuable new information such as why and how creatures in both the human and non-human worlds have learned to dance and sing. Yet, this miraculous biophony – – this concerto of the natural world – – is now under serious threat of complete annihilation. Not only are we moving toward a silent spring, but a silent summer, fall and winter, as well. ”