Environmental Engineering Reference
In-Depth Information
of factors and in order to separate wind farm effects from other anthropogenic or
natural impacts, requires large sample sizes, which cannot be achieved in this study.
Therefore the survey results are provided with no formal analysis, and hence only
cursory conclusions can be drawn.
A new WBSE nest was established at the BPWF in 2005 (Tasmanian Natural
Values Atlas nest number 1447) and was monitored from this period to the comple-
tion of the 2009 breeding season (the surveyed nests were changed after this time,
see the reasoning and details in Sims et al.
this volume
).
Display Period and Post-collision Eagle Observations
The aim of these surveys was to obtain indications of the factors contributing to
eagle collision risk. Display period (1 June-31 August, as defi ned in the environ-
mental management plans for these wind farms) and post-collision observations
were conducted from 2006 to 2010. The former were instigated on the assumption
that eagle collision risk was higher during the display period. Post-collisions obser-
vations were instigated in 2006 to investigate why an eagle collision may have
occurred, but they evolved into a requirement of the State regulator. Both of these
surveys were a form of surveillance monitoring (that is, largely untargeted with
undefi ned
a priori
hypotheses and protocols). Over time, a requirement was added
by the State regulator that turbine shutdowns occur when eagles were observed in
close proximity to a turbine, a measure intended to prevent collisions (see Sims
et al.
this volume
).
Observers viewed and recorded the behaviour and movements of eagles from
vantage points at both wind farms. Observers were present on site from dawn to
dusk, which in the height of summer was 14 h. The full details of the survey proto-
col are found in Hull and Muir (
2013
).
Results
Collision Monitoring
To the date of writing (December 2012), there have been 13 WTE and three WBSE
collisions at BPWF, and fi ve WTE and zero WBSE collisions at SBWF (
Appendix
).
In many cases the precise collision date was not known because carcasses were
not always detected immediately after the collision. Two collisions were observed
and these are the only collisions for which the date and turbine can be determined
with complete confi dence. The average annual collision rate is provided in Table
1
.
No inter-annual differences in collision rates were found, with no 1 year being
signifi cantly different from any other (graphical test showed overlapping confi dence
levels). The Chi
2
tests found BPWF: X
2
= 11.3 <
X
2
0.95, DF = 9, p > 0.25; SBWF:
