What does noise affect?
- Noise Effects & Mitigation
- How does Noise affect People?
- How does Noise affect Domestic Animals and Wildlife?
- Other Noise Related Effects
Some studies report that the effects of aircraft noise on domestic animals is uncertain. Some behavioral responses to military overflights have been noted. However, they generally seem to adjust to the disturbances over time.
Mammals in particular appear to react to noise at sound levels higher than 90 dB. Responses include:
- The startle response
- Freezing (becoming temporarily stationary)
- Fleeing from the sound source
Many studies on domestic animals suggest that some species appear to adjust to some forms of sound disturbance (Manci, et al. 1988).
Some studies have reported such primary and secondary effects as:
- Reduced milk production and rate of milk release
- Increased glucose concentrations
- Decreased levels of hemoglobin
- Increased heart rate
- Reduction in thyroid activity
Some reviewers say that earlier studies did not necessarily provide clear evidence of cause and effect (Cottereau 1978). In contrast, many studies conclude that there is no evidence that aircraft overflights affect:
- Feed intake
- Production rates
Many people are concerned about aircraft overflight effects on:
- Pregnant cattle
- Milk production
- Cattle safety
In response, the U.S. Air Force prepared a handbook for environmental protection. This handbook summarizes the literature on the impacts of low-altitude flights on livestock (and poultry). It includes specific case studies conducted in airspaces across the country. Adverse effects have been found in a few studies but have not been reproduced in other similar studies.
- One study suggested that 2 of 10 cows in late pregnancy aborted after showing rising estrogen and falling progesterone levels. These increased hormonal levels were reported as being linked to 59 aircraft overflights. The remaining eight cows showed no changes in their blood concentrations. These calved normally (U.S. Air Force 1994b).
- A similar study reported abortions occurred in three out of five pregnant cattle. This was after exposing them to flyovers by six different aircraft (U.S. Air Force 1994b).
- Another study suggested that feedlot cattle could stampede and injure themselves when exposed to low-level overflights (U.S. Air Force, 1994b).
- A number of other studies investigated the effects of jet aircraft noise and sonic booms on the milk production of dairy cows (Parker and Bayley 1960; Casady and Lehmann 1967; Kovalcik and Sottnik 1971). It was determined that milk yields were not affected. This was particularly evident in those cows that had been previously exposed to jet aircraft noise.
- Another study examined the causes of 1,763 abortions in Wisconsin dairy cattle over a one-year time period. None were associated with aircraft disturbances (U.S. Air Force 1994b).
- In 1987, seven livestock operators were contacted for production data. No effects of low-altitude and supersonic flights were noted.
- In yet another study, 3 out of 43 cattle previously exposed to low-altitude flights showed a startle response to an F/A-18 aircraft flying overhead (U.S. Air Force 1994b). The aircraft was 500 feet above ground level and traveling at 400 knots. The cattle ran for less than 10 meters. They resumed normal activity within one minute.
- Beyer (1983) found that helicopters caused more reaction than other low-aircraft overflights.
- However, he also found that helicopters at 30 to 60 feet overhead did not affect milk production and pregnancies of 44 cows and heifers in a 1964 study (U.S. Air Force 1994b).
- He also reported that five pregnant dairy cows in a pasture did not exhibit fright-flight tendencies. They also did not disturb their pregnancies after being overflown by 79 low-altitude helicopter flights and 4 low-altitude, subsonic jet aircraft flights (U.S. Air Force 1994b).
- A 1956 study (U.S. Air Force, 1994b) found that the reactions of dairy and beef cattle to noise from low-altitude, subsonic aircraft were similar to those caused by:
- paper blowing about
- strange persons
- other moving objects
In a report to Congress, the U. S. Forest Service concluded that the evidence shows that the risks of damage are small (U.S. Forest Service 1992). When aircraft approaches at 50 to 100 meters, they concluded that there is no evidence that:
- Mothers and young are separated
- Animals collide with obstructions (unless confined)
- They travel over dangerous ground at too high a rate
These varied study results suggest that the confining of cattle could increase animal response to aircraft overflight. However, there is no proven cause-and-effect link between startling cattle from aircraft overflights and abortion rates or lower milk production.
Several studies report a varied response of horses to low-altitude aircraft overflights.
- Observations made in 1966 and 1968 noted that horses galloped in response to jet flyovers (U.S. Air Force 1993).
- Bowles (1995) observed horses exhibiting:
- Intensive flight reactions
- Random movements
- Biting/kicking behavior
However, no injuries or abortions occurred. The mares seemed to adapt somewhat to the flyovers over the course of a month. Overflights did not appear to affect either survivability or reproductive success (U.S. Air Force 1994b).
- LeBlanc, et al. (1991) looked at the effects of F-14 jet aircraft noise on pregnant mares. They specifically focused on any changes in:
- Pregnancy success
- Cardiac function
- Hormonal production
- Rate of habituation
"Flight-fright" reactions were observed. This causes increases in heart rates and serum cortisol concentrations. The mares, however, did adapt to the noise. Levels of anxiety and mass body movements were the highest after initial exposure. The intensities of responses decreased after the initial exposure. There were no differences in pregnancy success when compared to a control group.
Generally, the findings for swine appear to be similar to those for cows and horses. Effects from aircraft noise appear to be minor.
- Studies of continuous noise exposure reported influences on short-term hormonal production and release.
- Additional constant exposure studies by Dufour (1980) indicated the observation of stress reactions, hypertension, and electrolyte imbalances.
- Another study by Bond, et al. (1963) demonstrated no adverse effects on the pigs':
- Feeding efficiency
- Weight gain
- Ear physiology
- Thyroid and adrenal gland condition
Heart rate increases were recorded. However, they returned to normal after the noise had stopped. Conception rates and offspring survival did not appear to be influenced by exposure to aircraft noise.
- Studies using simulated aircraft noise at levels of 100 dB to 135 dB found only minor effects on:
- Rate of feed utilization
- Weight gain
- Food intake
- Reproduction rates of boars and sows
Also, no injuries or inner ear changes were observed (Manci, et al. 1988; Gladwin, et al. 1988).
The U.S. Air Force published a paper on the effects of low-altitude overflights (below 1,000 ft) on domestic fowl. Overflight activity was shown to have minor effects (U.S. Air Force 1994a). The paper did recognize that given certain circumstances, harmful effects can be serious. Some of the effects can be:
- Panic reactions
- Reduced productivity
- Effects on marketability (for example, bruising of the meat caused during "pile-up" situations)
A short-term startle response is the typical reaction. This response stops as soon as the noise stops. Within a few minutes, all activity returns to normal (U.S. Air Force 1994a). More severe responses are possible depending on:
- The number of birds
- The frequency of exposure
- Environmental conditions
Large crowds of birds and birds not previously exposed are more likely to pile up in response to a noise. The previously unexposed birds are more likely to incite panic crowding. This tendency is reduced within five exposures to the noise (U.S. Air Force 1994a). This suggests that the birds adapt fairly quickly. Egg productivity was not badly affected by infrequent noise bursts. This was seen even at exposure levels as high as 120 to 130 dBA.
Between 1956 and 1988, there were 100 recorded claims against the Navy for alleged damage to domestic fowl. The number of claims averaged three per year. The number of claims peaked following publications of studies on the topic in the early 1960s (U.S. Air Force 1994a). Many of the claims were disproved or did not have sufficient supporting evidence. The claims were filed for the following alleged damages:
- 55% for panic reactions
- 31% for decreased production
- 6% for reduced hatchability
- 6% for weight loss
- less than 1% for reduced fertility
There has not been a concerted or widespread effort to study the effects of aircraft noise on commercial turkeys.
- One study (Bowles, et al. 1990) involving turkeys examined:
- the differences between simulated versus actual overflight aircraft noise
- turkey responses to the noise
- weight gain
- evidence of adaptation
The study suggested that:
- turkeys adapted to jet aircraft noise quickly
- there were no growth rate differences between the experimental and control groups
- there were some behavioral differences that increased the difficulty in handling individuals within the experimental group
Low-altitude overflights were shown to cause turkey flocks that were kept inside turkey houses to occasionally pile up. They experience high mortality rates due to the aircraft noise and a variety of disturbances unrelated to aircraft (U.S. Air Force 1994a).
Beyer, D. 1983. Studies of the Effects of Low-Flying Aircraft on Endocrinological and Physiological Parameters in Pregnant Cows. Veterinary College of Hannover, Muenchen, Germany.
Bond, J., C.F. Winchester, L.E. Campbell, and J.C. Webb. 1963. The Effects of Loud Sounds on the Physiology and Behavior of Swine. U.S. Department of Agriculture Agricultural Research Service Technical Bulletin 1280.
Bowles, A.E. 1995. Responses of Wildlife to Noise. In R.L. Knight and K.J. Gutzwiller, eds., "Wildlife and Recreationists: Coexistence through Management and Research," Island Press, Covelo, California, pp.109-156.
Bowles, A.E., C. Book, and F. Bradley. 1990. Effects of Low-Altitude Aircraft Overflights on Domestic Turkey Poults. USAF, Wright-Patterson AFB, AL/OEBN Noise Effects Branch.
Casady, R.B., and R.P. Lehmann. 1967. Response of Farm Animals to Sonic Booms. Studies at Edwards Air Force Base, June 6-30, 1966. Interim Report, U.S. Department of Agriculture, Beltsville, Maryland, p. 8.
Cottereau, P. 1978. The Effect of Sonic Boom from Aircraft on Wildlife and Animal Husbandry. In "Effects of Noise on Wildlife," Academic Press, New York, New York, pp. 63-79.
Dufour, P.A. 1980. Effects of Noise on Wildlife and Other Animals: Review of Research Since 1971. U.S. Environmental Protection Agency.
Gladwin, D.N., K.M. Manci, and R. Villella. 1988. Effects of Aircraft Noise and Sonic Booms on Domestic Animals and Wildlife. Bibliographic Abstracts. NERC-88/32. U.S. Fish and Wildlife Service National Ecology Research Center, Ft. Collins, Colorado.
>Kovalcik, K., and J. Sottnik. 1971. Vplyv Hluku Na Mliekovú Úzitkovost Kráv [The Effect of Noise on the Milk Efficiency of Cows]. Zivocisná Vyroba, Vol. 16, Nos. 10-11, pp. 795-804.
Kryter, K.D. 1984. Physiological, Psychological, and Social Effects of Noise. NASA Reference Publication 1115. July.
LeBlanc, M.M., C. Lombard, S. Lieb, E. Klapstein, and R. Massey. 1991. Physiological Responses of Horses to Simulated Aircraft Noise. U.S. Air Force, NSBIT Program for University of Florida.
Manci, K.M., D.N. Gladwin, R. Villella, 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.
Parker, J.B., and N.D. Bayley. 1960. Investigations on Effects of Aircraft Sound on Milk Production of Dairy Cattle, 1957-58. U.S. Agricultural Research Services, U.S. Department of Agriculture, Technical Report Number ARS 44-60.
U.S. Air Force. 1994a. Air Force Position Paper on the Effects of Aircraft Overflights on Domestic Fowl. Approved by HQ USAF/CEVP. 3 October.
U.S. Air Force. 1994b. Air Force Position Paper on the Effects of Aircraft Overflights on Large Domestic Stock. Approved by HQ USAF/CEVP. 3 October.
U.S. Air Force. 1993. The Impact of Low Altitude Flights on Livestock and Poultry. Air Force Handbook. Volume 8, Environmental Protection. 28 January.
U.S. Forest Service. 1992. Report to Congress: Potential Impacts of Aircraft Overflights of National Forest System Wilderness. U.S. Government Printing Office 1992-0-685-234/61004, Washington, D.C. von Gierke, H.E. 1990. The Noise-Induced Hearing Loss Problem. NIH Consensus Development Conference on Noise and Hearing Loss, Washington, D.C. 22-24 January.
Photo Credit: Stone Meadow Farm