Draft National Wind Farm Development Guidelines - July 2010

used throughout these Guidelines as a term of convenience for all causes of bird and bat
deaths that may result from interactions with wind turbines. These include barotrauma,
potential traumatic effects of turbulence caused by rotors, and direct collision strikes (see
Section D.6 for a glossary of terms).
Account should be taken of the fact that mortalities due to turbine collisions are either not
possible or are not considered to be an issue for some species of birds. Assessment of
collision risk for the following categories of birds is not necessary or is unlikely to be required
for most sites within Australia:
• Introduced and feral taxa.
• Flightless and near-flightless birds.
• Other taxa that rarely fly within or through rotor-swept-height.
Some species routinely fly within or through rotor-swept-height (which for current turbines is
generally in the range 30-130 metres above the ground), but many other species rarely if
ever fly in that height range. Flight-height data collected in south-eastern Australia
indicates that many bird taxa rarely fly above 25 metres (Biosis Research unpublished
data) and that interactions with turbines do not need to be assessed for these birds other
than for exceptional sites or circumstances (see also Section D.7). The potential for
exceptional circumstances should be evaluated for each wind farm. Examples may
include locations on defined routes of migration or other long-distance movements if birds
there fly at greater heights than they do during the majority of their routine activities. Unless
the species in question is also a key taxon, assessment is unlikely to be required.
All Australian bat species have capacity to fly within rotor-swept height and, while some
may do so less than others, current knowledge is insufficient to suggest the exclusion of any
key bat taxa from this component of the assessment.
If key taxa with capacity to fly at rotor height are known from the site, further preliminary
investigations of those taxa will be necessary. For resident species, their home range
requirements should be considered and for all key species that might use the site their
foraging, roosting, breeding and other species-specific needs are to be considered at this
phase. Other aspects that should be given preliminary consideration relative to potential
risks for the species involved are typical sizes of flocks, behaviours, where they are most
readily detected and particular behaviours or habitat preferences that may expose them
to high risk.
This phase does not require full or detailed assessments, and information gathering at this
phase does not need to be of a standard that might provide inputs to detailed risk
assessment. The information does, however guide later evidence gathering studies, and is
critical to ensure full alignment of pre- and post-construction assessments using BACI
(Before – After – Control – Impact) designs. Local or otherwise expert knowledge gleaned
during this preliminary phase may be supported by targeted pilot studies to establish
background methodologies and necessary parameters that will guide later phase surveys
and assessments. Pilot surveys are short field studies to further identify and to scope
potential issues. They allow approximation of relevant information such as typical
population on site, number of movements on site, seasonal dependencies, observability
and detectability. If occurrence of key taxa at the site is likely to be seasonal, then pilot
studies must be timed to maximise potential to obtain such information.
The principal purpose of such trials is to establish a sound basis for the need and
subsequent design of any more detailed investigations of risk for key species specific to the
site.
If there is an identified potential for a key species to interact with turbines, the assessment
should proceed to the next phase. If not, relevant authorities may determine that no
further assessment of risk is required for birds or bats.
Page 124 Draft National Wind Farm Development Guidelines – 2 July 2010