Biology Reference
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Fig. 6.16
Adults and juveniles of California ground squirrel (
Spermophilus beecheyi
) close to
wind turbines have an increased alertness response to conspecific alarm calls. The difference
between baseline and playback results was highly significant statistically both in control site and
near turbine. Values were higher at the turbine than at the control site (Reproduced with permis-
sion from Rabin et al.
2006
)
A Danish study has demonstrated that height and closeness, expressed as vertical
virtual angle (VVA), were better predictors of the noise than the measurement of
the noise level per se. When a turbine is placed close to the home of a respondent, it
becomes clear that the feeling of intrusiveness could be very strong (Pedersen and
Larsman
2008
).
Complex reactions have been observed in wild animal populations. Rabin
et al. (
2006
) have investigated the effect of such devices on a population of
California ground squirrels (
Spermophilus beecheyi
) at the Altamont Pass Wind
Resource Area of Northern California (Fig.
6.16
).
This species alerts the arrival of predators with specific alarm calls and the noise
of turbines significantly masks this signal that is important for the entire population.
Two populations were selected for this study, one population close to the turbines
and another far from the windfarm. The population living close to the turbine was
noted to have a new behavior consisting of an elevated rate of vigilance and a return
to their burrows when alarm calls were uttered. This difference was proved not to
depend on other environmental factors such as population density, predator pres-
sure, or environmental characteristics.
At the beginning of the use of wind turbines, displacement noise annoyance was
caused by mechanical noise, but actually with technological improvement of the
design, only a residual noise is produced by a broadband aerodynamic noise from
the blades close to a turbine. The noise (a distinct “swooshing”) is similar to a
aircraft background noise.
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