Environmental Engineering Reference
In-Depth Information
on wildlife, the results of a physical model analyzing the impacts of transporta-
tion noise on listening area (i.e., the active space of vocalization in which animals
search for sounds) of animals resulted in some significant findings. With a noise
increase of just 3 dB—a noise level indentified as “just perceptible to humans”—
this increase corresponded to a 50% loss of listening area for wildlife (Barber et
al., 2010). Other data suggest that noise increases of 3 to 10 dB correspond to 30 to
90% reductions in alerting distances (i.e., the maximum distance at which a signal
can be heard by an animal, particularly important for detecting threats) for wildlife,
respectively (Barber et al., 2010). Impacts of noise could thus be putting species at
risk by impairing signaling and listening capabilities necessary for successful com-
munication and survival.
Swaddle and Page (2007) tested the effects of environmental noise on pair prefer-
ence selection of zebra finches. They noted a significant decrease in females' prefer-
ence for their pair-bonded males under high environmental noise conditions. Bayne
et al. (2008) found that areas near noiseless energy facilities had total passerine
(i.e., birds of the order Passeriformes which includes more than half of all bird spe-
cies) density 1.5 times greater than areas near noise-producing energy facilities.
Specifically, white-throated sparrows, yellow-rumped warblers, and red-eyed vireos
were less dense in noisy areas. Habib et al. (2007) found a significant reduction in
ovenbird pairing success at compressor sites (averaging 77% success) compared to
noiseless well pads (92%). Quinn et al. (2006) found that noise increases perceived
predation risk in chaffinches, leading to increased vigilance and reduced food intake
rates, a behavior that could over time result in reduced fitness. Francis et al. (2009)
showed that noise alone reduced nesting species richness and led to a different com-
position of avian communities. Although they found that noise disturbance ranged
from positive to negative, response were predominately negative.
Schaub et al. (2008) investigated the influence of background noise on the forag-
ing efficiency and foraging success of the greater mouse-eared bat, a model selected
because it represents an especially vulnerable group of gleaning bats (predators of
herbivorous insects) that rely on their capacity to listen for prey rustling sounds to
locate food. Their study clearly found that traffic noise, and other sources of intense,
broadband noise, deterred bats from foraging in areas where these noises were pres-
ent, presumably because these sounds masked relevant sounds or echoes the bats use
to locate food.
Although there are few studies specifically focused on the noise effects of wind
energy facilities on birds, bats, and other wildlife, scientific evidence regarding
the effects of other noise sources (e.g., transportation) is widely documented. The
results show, as documented in the various examples above, that varying sources
and levels of noise can affect both the sending and receiving of important acoustic
signaling and sounds. This can also cause behavioral modifications in certain spe-
cies of birds and bats such as decreased foraging and mating success and overall
avoidance of noisy areas. The inaudible frequencies of sound may also have nega-
tive impacts on wildlife.
To this point we have focused on wildlife effects of wind turbines and wind
turbine farms on birds. Little is known about the effects of noise related to wind
turbines on invertebrates, fish, reptiles and amphibians, and various mammals. As
