Sources of noise that have the potential to effect wildlife include aircraft overflights, recreational activities such as snowmobiling and motorboating, automobile traffic, and heavy machinery and equipment. The effects of aircraft noise have been studied more intensively because of their threat to wildlife populations in national and state refuges and parks. Impacts to wildlife habitat in remote areas have increased from military aircraft overflights and helicopter activity related to the tourism and resource extraction industries (National Park Service, 1994).
The study of animal response to noise is a function of many variables including characteristics of the noise and duration, life history characteristics of the species, habitat type, season and current activity of the animal, sex and age, previous exposure and whether other physical stressors (e.g. drought) are present (Manci, et al., 1988).
Physiological responses: Disturbances from aircraft noise range from mild, such as an increase in heart rate to more damaging effects on metabolism and hormone balance. Long term exposure to noise can cause excessive stimilation to the nervous system and chronic stress that is harmful to the health of wildlife species and their reproductive fitness (Fletcher, 1980; 1990).
Behavioral responses: Responses vary among species of animals and birds and among individuals of a particular species. Variations in response may be due to temperament, sex, age, and prior experience with noise. Minor responses include head-raising and body-shifting. More disturbed mammals will trot short distances; birds may walk around flappping wings. Panic and escape behavior results from more severe disturbances (National Park Service, 1994).
Behavioral and physiological responses have the potential to cause injury, energy loss (from movement away from noise source), decrease in food intake, habitat avoidance and abandonment, and reproductive losses (National Park Service, 1994). Studies have shown that when certain bird species are flushed from nests in response to noise, eggs are broken and young are exposed to injury and predators (Bunnell et al., 1981; Gladwin, 1987). Young mammals have been trampled as adults attempt to flee from aircraft (Miller and Broughton, 1974). Another study compared mortality rates of caribou calfs exposed to overflights to those not exposed (Harrington and Veitch, 1992). Mortality rates were significantly greater in the exposed group. Milk release may have been inhibited in mothers disturbed by the noise leaving calfs malnourished.
Animals rely on hearing to avoid predators, obtain food, and communicate. Auditory systems of some animals are particularly at risk to physical damage from chronic noise, for example desert animals that have evolved an acute sense of hearing. Studies have documented hearing loss caused from motorcycle noise in the desert iguana (Bondello, 1976) and the kangaroo rat, an endangered species (Bondello and Brattstrom, 1979)
Ninety-eight species of birds and mammals on national park lands have been identified as threatened or endangered. The impacts on these species from aircraft noise are largely undocumented. Some of the species became threatened or endangered because of loss of habitat. Further relocation necessary because of noise disturbance might not be possible for these species (National Park Service, 1994).
Studies are needed to determine the long term effects of noise disturbance. Long-term studies have been difficult because of the effort required and the complexity of the variables affecting animal survivorship (National Park Service, 1994).
Many important studies on wildlife can be found on our website. They include:
List of References
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LIST OF REFERENCES
Bondello, M.C., 1976. The effects of high-intensity motorcycle sounds on the acoustical sensitivity of the desert iguana, Dipsosaurus dorsalis. M.A. Thesis. California State University, Fullerton. 37 pp.
Bondello, M.C. and B.H. Brattstrom, 1979. The experimental effects of off-road vehicle sounds on three species of desert invertebrates. Report to the Bureau of Land Management. 61 pp.
Bunnell, F. L., Dunbar, D., Koza, L. and G. Ryder, 1981. Effects of disturbance on the productivity and numbers of white pelicans in British Colombia - observations and models. Colonial Waterbirds 4:2-11.
Fletcher, J.L., 1980. Effects of noise on wildlife: a review of relevant literature 1971-1978. Pages 611-620 in J.V. Tobias, G. Jansen, and W.D. Ward, eds. Proceedings of the Third International Congress on Noise as a Public Health Problem. Am. Speech-Language-Hearing Assoc., Rockville, MD.
Fletcher, J.L., 1990. Review of noise and terrestrial species: 1983-1988. pp. 181-188 in: B. Berglund and T. Lindvall, eds. Noise as a Public Health Problem Vol. 5: New Advances in Noise Research Part II. Swedish Council for Building Research, Stockholm.
Gladwin, D.N., Asherin, D.A and K.M. Manci, 1987. Effects of aircraft noise and sonic booms on fish and wildlife: Results of a survey of U.S. Fish and Wildlife Service endangered species and ecological services field offices, refuges, hatcheries, and research centers. NERC-88/30. USFWS, National Ecology Research Center, Fort Collins, CO. 24 pp.
Harrington F.H.and A.M.Veitch, 1992. Calving success of woodland caribou exposed to low-level jet fighter overflights. Arctic 45:213-218.
Manci, K.M., Gladwin, D.N., Villella, R. and M.G. Cavendish, 1988. Effects of aircraft noise and sonic booms on domestic animals and wildlife: A literature synthesis. U.S. Fish and Wildlife Service. National Ecology Research Center, Ft. Collins, CO NERC-88/29. 88 pp.
Miller, F.L. and E. Broughton, 1974. Calf mortality on the calving grounds of Kaminuriak caribou during 1970. Canadian Wildlife Service Report Series No. 26, Information Canada, Ottawa.
National Park Service, 1994. Report to Congress, Report on effects of aircraft overflights on the National Park System.