Abstract
Project purpose
The construction and operation of onshore wind farms pose potential risks to birds and bat species. Risks may include direct collisions with turbines, displacement from preferred habitats, habitat destruction and barrier effects (the physical and visual obstruction of bird and bat flight paths) leading to altered movement patterns. This report collates information on the ecological attributes of all birds and bats in Australia to assess potential risks to them from wind farms. It presents the outcomes in a user-friendly format that can be used by proponents and regulators. A harmonised, consistent approach to identifying species at highest risk from onshore wind farm developments in Australia will help to streamline assessment processes and reduce impacts on birds and bats. Categorising relative risk at a regional scale highlights those bird and bat taxa that are at highest risk from the potential impacts of wind farms. It indicates where more detailed, site-specific consideration is required for a proposed (or operational) development area. Importantly, the outcomes of the ecological risk assessment should guide survey design to ensure they are appropriate for the ecological characteristics of high-risk species. The risk assessment also provides regulators with relevant information when considering species of concern in an area during the assessment process. See Section 1 Introduction for further information.
Methods used
An ecological risk assessment was undertaken using the intrinsic ecological, morphological and life history attributes of 1095 bird and 81 bat taxa (covering all bird and bat species in Australia). It provides a relative ranking of risk of negative interactions with onshore wind farms in Australia. Ecological attributes of these birds and bats indicate the likelihood of interactions with a wind farm and the population-level resilience to such impacts. The likelihood of interactions was scored based on attributes of flight activity (time spent flying and height relative to the height of turbines), flight characteristics (based on wing morphology and body weight), and habitat specialisation for each taxon. The estimated resilience of the current population to immediate impacts as well as the estimated duration of recovery from any potential impacts was scored based on a contemporary assessment of the population status and trends in combination with the generation time of each species. Each individual attribute was scored on scale of 1−5 and then combined to give an overall risk score for the taxon. The limited availability of species-specific empirical data was addressed by using peer-reviewed, publicly available data, trait-based ecological groupings and testing with experts who reviewed input parameters and risk assessment methods. Acknowledging the limitations in data availability, experts reviewed and refined the details of the ecological traits used in parameterising the risk frameworks, in a workshop setting. See Section 2 Methods for further information.
Summary of the results
The thresholds between low-to-medium risk and medium-to-high risk were calibrated to the 25th and 75th percentiles of the overall risk scores. For birds, 238 taxa were classed as low risk, 583 as medium risk and 274 as high risk. For bats 17 taxa were classed as low risk, 44 as medium risk and 20 as high risk. The two highest risk bird species were Australian Palm Cockatoo (Probosciger aterrimus macgillivrayi) and Baudin's Black Cockatoo (Zanda baudinii) due to their particular flight attributes, 3 Impacts on birds and bats from onshore wind farms in Australia: an ecological risk assessment conservation status and long generation times. The two highest risk bat species were Arnhem Leaf nosed Bat (Hipposideros inornatus) and the Lesser Large-eared Horseshoe Bat (Rhinolophus intermediate). See Section 3 Results for more information. Details of the individual attribute scores and the resulting overall risk categories are provided for birds and bats as separate appendices. The spreadsheets are filterable by state or territory. See Appendices 2−5 for more information.
Confidence, constraints and caveats
This is a general risk assessment and doesn’t account for site-specific characteristics that a proponent would need to consider when determining the potential environmental impact of a proposal. The limited availability of species-specific data means that the final risk assessment relies on generalised, trait-based data and expert opinion to estimate an overall score of relative risk. Importantly, the approach used here recognises the need to make progress using the best information currently available to undertake an ecological risk assessment, rather than being hindered by incomplete data. The inherent data limitations and contingent uncertainties underscore the need to employ methods that allow for risk scores to be updated as new information becomes available. The information in this document is intended as an initial guide. The actual level of risk to which individual taxa are exposed cannot be fully known due to limitations of available data. Overall, the area of greatest uncertainty is the relative amount of time that different species spend at collision risk height over an annual cycle. This includes the dispersive or migratory behaviours of birds and bats, for which empirical data on nocturnal flights is particularly limited. The criteria applied to determine whether a taxon is included in a particular state or territory may mean that some species that either occur infrequently or are under-reported in a region may not be included in that state or territory’s list. Sharing of data from bird and bat surveys, including those in association with wind farms, will help to improve and update our understanding of the behaviours and distribution of all taxa, especially for those that are at high risk from interactions with wind farms. The ecological risk assessment provides a measure of potential risk; however, assessing realised risk is hampered by a lack of consistent data on actual or reported impacts of wind farms on birds and bats in Australia. Improving the understanding of potential and realised risk requires consistent methods and centralised reporting of the total numbers of bird and bat mortalities associated with wind farms. See Section 4 Discussion and risk assessment outcomes for more information.
How to use this report
This ecological risk assessment is a precursor to the development of baseline data required to assess, avoid, mitigate and manage impacts of onshore wind farms. It allows proponents and regulators to identify species that should be investigated further in relation to impacts from specific proposed developments. The approach provides a rigorous method to identify taxa that may be at high risk of negative impacts from onshore wind farms. Furthermore, the attribute score can be used to determine whether a taxon’s status as high risk is driven by wind farm-specific risks, low population resilience or a combination of both. In doing so, it provides proponents and regulators with an important tool for determining the most appropriate approaches for identifying and managing risks to birds and bats from onshore wind farms. See Section 5 Best and emerging practice to determine and mitigate impacts for more information. 4 Impacts on birds and bats from onshore wind farms in Australia: an ecological risk assessment