Environmental Engineering Reference
In-Depth Information
effective in the case of Tasmanian devils
Sarcophilus harrisii
, see Hawkins et al.
2006
, where gross impacts were operating) or might appear to save time as it does
not involve detailed hypothesis testing and experimental design. However, in our
case it was an ineffective approach because it did not provide insights into why
eagles collided with turbines and was therefore unable to inform management
strategies.
An important conclusion from the review process was that studies needed to
use the most appropriate monitoring strategy to collect the correct data. In addition,
the monitoring strategy needed to be both feasible and practical. For example, the
surveillance monitoring was particularly onerous (838 days of full daylight eagle
observations undertaken by human observers), and expensive. Furthermore, it was
diffi cult to staff the surveillance program with appropriately skilled personnel in
a manner that minimised observer fatigue (see the Effects of Observers study in
Hydro Tasmania
2013
). The requirement to undertake observations at the
same time as conducting pauses on turbines most likely increased the stress level
on observers.
The review revealed that the management measures implemented or trialled on
site had varying levels of success. There are no data available to assess the success
of managing eagle food resources near the turbines, however, it does appear logical
that a reduction in food supply will reduce eagle foraging activity around turbines.
It should be noted, though, that the success of this strategy is predicated on foraging
being a key risk factor in turbine collisions, and this is yet to be demonstrated at
these sites (see Hull et al.
2014
). Secondly, it assumes that there are no negatives or
unintended consequences associated with this action. Following consideration of
these issues, the review team decided to continue this action because the advantages
appeared to outweigh any negatives.
The two interventions implemented during the operational stage of these wind
farms, reactive shutdowns and sector management, were both found to be ineffec-
tive at demonstrably reducing the eagle collision rate. In the case of reactive
shutdowns, it was impossible to design effective guidelines to direct an observer
about when to pause a turbine. The fi nal guideline in place (before the program
ceased) included large buffers so that any eagle movements occurring within these
buffers triggered a turbine pause. However, an observed mortality under this guide-
line indicated the high potential for this technique to fail. The review concluded that
the program was both expensive and onerous to implement, particularly given it had
no material effect on the collision rate. Further, the review found that while a great
deal of effort had been expended on designing a system that could communicate
directly with the turbines, the system could not (and potentially never could) be
activated quickly enough to match high speed eagle movements. Finally, there is
evidence that eagles fl y closer to shutdown turbines than active turbines (Hull and
Muir
2013
), which could lead to modifi cations in the behaviour of eagles that may
increase the collision risk.
The evaluation of sector management concluded that shutting down turbines in
specifi c wind conditions was a very coarse strategy that resulted in high production
