Biology Reference
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Fig. 6.2
Relationship
between background noise
level and median number of
songs per bout in chaffinch
(
Fringilla coelebs
)
(Reproduced with
permission from Brumm
and Slater
2006
)
demonstrated that the spectral profiles can be significantly and consistently different
according to the habitat. This finding suggests that the ambient noise, because of its
regularity, can drive the signal evolution of vocal animals. The masking of ambient
noise can represent a significant adaptive mechanism to improve the signal-to-noise
ratio with benefits for the species that can do this performance in an evolutive time.
Considering the growing intrusion of anthropogenic noise and the rapid modification
of habitats, the sonic environment can change abruptly without allowing species to
adapt their communicative traits, as stressed by Slabbekoorn in the conclusive
comment. This fact represents the “ecological debt” sensu Tilman et al. (
1994
)that
can produce dramatic changes in biological diversity in future time.
6.7 Noise Pattern as a Source of Environmental Pollution
With the term noise pollution we intend every negative consequence produced by a
noisy ambience on animals and human life as well.
Humans have dramatically changed many environments across the world,
producing growing noise as one of the major consequences of economic develop-
ment (Hanson
2008
). As recently outlined by Frisk (
2012
), the increase of ambient
noise levels in the sea is strictly related to the global economic trends. In the
period 1950-2007, in the open oceans there has been an increase of 3.3 dB per
decade (Fig.
6.3
). The effects of such diffuse noise intrusion are not easy to detect
because they influence the behavior of animals and cannot be monitored as can a
chemical pollutant.
Among the consequences of noise on ecological and behavioral processes, noise
can disrupt predatory-prey interactions, and it could facilitate the success of species
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