Managing Cumulative Wind Farm Impacts on the Brolga

Grus rubicunda in Victoria, AustraliaRichard Hill Department of Sustainability and Environment, Casterton, Victoria. Richard.hill@dse.vic.gov.au

Phillip du Guesclin Port Fairy, Victoria

Mathew Herring Consultant Ecologist, Albury, NSW.

Michael McCarthy Centre for Ecological Analysis and Synthesis, University of Melbourne, Victoria

Ian Smales Biosis Research, Victoria.

Summary

South-west Victoria has some of the most prospective wind resources in Australia. Within this development area occurs a threatened population of an Australian crane, the Brolga. Managing the cumulative risk to Brolgas of planned and projected multiple wind farm developments within this range is a key environmental issue.

Guidelines for the assessment, avoidance and mitigation of potential impacts of wind farm development provide standards for assessment of Brolga populations, and recommendations for design and mitigation of any impacts. The overall approach is to avoid impacts as much as possible by adopting turbine-free buffers around essential breeding and flocking habitats, and quantifying and offsetting any remaining impacts using collision risk and population viability models. Impacts and offsets are quantified at individual developments with the aim that each development has no netimpact on the Victorian population of the Brolga. By requiring each individual wind farm proposal have no net impact, cumulative impacts of multiple wind farm developments on this species are proposed to be avoided. This approach avoids some of the risks inherent in more traditional approaches to managing cumulative impacts.

Stockyard Hill proposed wind farm

•Large project (23,500 ha, 240 turbines)

•Substantial brolga breeding habitats present.

•Potential barrier effect of large N-S line of wind turbines

•Breeding home ranges described and turbines excluded

•Two E-W turbine-free corridors to avoid barrier effect

•After site design CRM estimated an annual turbine collision rate of 0.2 birds per year based on an (assumed) avoidance rate of 95% (Smales 2009).

•CRM of proposed new powerlines estimated annual collision rate of 0.03 birds per year (Smales 2009).

•Proposed offsets: Powerline marking at a flocking site used by 150 birds for up to 6 months per year to achieve minimum increased survival of 0.23 birds/year.

Turbine-free corridors

minimise barrier effect

South west Victoria is experiencing very rapid wind farm exploration and development within the range of the threatened Brolga

Stockyard Hill proposed

wind farm

References

Alonso, J.C., J.A. Alonso, and R. Munoz-Pulido. 1994. Mitigation of bird collisions with transmission lines through groundwiremarking. Biological Conservation 67, 129-134. Brown, W.M. & R. C. Drewien. 1995. Evaluation of two power line markers to reduce crane and waterfowl collision mortality. Wildlife Society Bulletin, 23(2), 212-16.BLA 2009. Proposed Stockyard Hill Wind Farm flora and fauna assessment. Brett Lane and Asscociates, Report No. 7132 (5.14)Desholm, M. 2009. Avian sensitivity to mortality: Prioritising migratory bird species for assessment at proposed wind farms. Journal of Environmental Management 90 (2009) 2672-2679. Drewitt, A.L. & R.H.W.Langston. 2006. Assessing the impacts of wind farms on birds. Ibis 2006 148, 29-42.DSE 2003. Brolga Grus rubicunda Action Statement. Department of Sustainability and Environment, Victoria.Gerjets, D. 2006. Wind Farm Planning. With the Conservation Aim of EU-Bird Sanctuary Diepholzer Moornierderung and FFH-Area Wietingsmoor.Herring, M. 2005 Threatened Species and Farming. Brolga: Management of breeding wetlands in northern Victoria c/o Arthur Rylah Institute for Ecological Research, Department of Sustainability and Environment, VictoriaNavarrete, L., Kerry Griffis-Kyle, David Haukos. 2011. Effects of wind farms on wintering Sandhill Cranes in the Southern High Plains of Texas. Texas Tech University, Lubbock, Texas, United States. Abstract of presentation to North American Crane Workshop, Nebraska, March 2011. Smales, I. 2009. Modelled risk of Brolga collisions with turbines at the proposed Stockyard Hill wind farm. Biosis Research, Victoria.

The Brolga

Common in northern Australia, a small sedentary population of the Brolga Grus rubicunda occurs in south-eastern Australia. The Victorian population comprises c. 600 individuals and is listed as a threatened species in the state (DSE 2003).

Wetland dependent throughout the year, breeding Brolgas vigorously defend territories. In the non-breeding season large flocking congregations of up to several hundred birds gather annually in the few remaining wetlands which remain during this time of annual drought (DSE 2003).

Brolgas make seasonal movements between breeding and flocking wetlands which may be many tens of kilometres apart (DSE 2003).

Potential Impacts of Wind Energy

Development on Brolgas

Collision: Brolgas are large, long-lived slow flying birds making them particularly vulnerable to increased mortality resulting from turbine collision (see Desholm2009).

Displacement/ DisturbanceThe presence of wind turbines, their associated infrastructure, and increased human activity associated with wind farm construction may lead to behavioural and physiological responses in brolgas. Navarette (et al. 2011) reported reduced habitat use, more clumped distributions, and more vigilance behaviour in Sandhill Cranes near windfarms in Texas. Currently we propose that Brolgas are less likely to use areas within 300m of a wind turbine.

Barrier effectsWind turbines may create barriers to flying Brolgas by interrupting seasonal or local flight paths. This may exclude birds from important habitat resources and/or cause birds to expend more energy on seasonal and local movements (Drewitt & Langston 2006). Gerjets(pers.comm.) recommended a minimum distance between wind farms of 1340m to avoid barrier impacts on migrating Common Cranes.

Guidelines for the Management of

Potential Windfarm Impacts on the

Brolga

We adopted a conservative approach to minimising impacts of planned wind farm development on Brolgas. This is because of the great uncertainty around the type and scale of impacts that may occur; the great uncertainties inherent in quantifying any impacts without species-specific data; and a requirement to manage the cumulative impacts of a planned very large wind farm industry per se on the Victorian Brolga population.

Objectives of the GuidelinesThe objective of these guidelines is to manage each wind farm development to achieve a zero net impact on the Victorian Brolga population, with an overall objective to avoid cumulative impacts of multiple wind farms planned, assessed and operated independently within the Brolga range in Victoria.

MethodologyThe assessment framework is a series of steps starting with wind farm design to remove altogether any ‘significant’ turbine-related impacts within the Brolga’s key breeding and flocking habitats, an estimation of any remaining risk using quantitative population modelling (PVA), and finally to use quantified management actions to offset that risk.

‘Significant impact’ is defined as any impact which will lead to a sustained reduction (of any magnitude) in total population size of the Victorian Brolga. To avoid cumulative impacts of multiple wind farm developments the guidelines aim to capture and offset impacts of all scales.

Triggers for use of the guidelines:

• the presence of breeding or flocking habitats within 10km of the proposed wind farm boundary (the ‘area of concern’);• the proposed development may create a barrier reducing movements between important Brolga habitats; • the location of proposed new powerlines may create new collision risks for Brolgas.

Assessment requirements:

A comprehensive assessment of the location, nature and extent of Brolga habitats within the wind farm area of concern and the potential for increased collision risk, indirect disturbance, and barrier effects.

• Comprehensive data on the occurrences of Brolgas within the area of concern;• Detailed description of spatial requirements of Brolgas within the area of concern• Detailed description of flight frequency, duration, and height for collision risk modelling CRM. • Assessment of the magnitude, extent and likelihood of potential direct and indirect impacts;

Methods may include:

• Roaming surveys• Aerial surveys• Gradient studies• Flight behaviour studies• Time budget studies

Site design and mitigation

1. Remove all significant impacts at Brolga breeding and flocking sites in the project design with turbine-free buffers.

2. Develop a site-specific collision risk model for remaining Brolga flights within/across the wind farm outside turbine-free buffers.

3. Estimate the impact of the proposed development on the Victorian Brolga population using PVA.

4. Equivalent or greater offsetting to produce a zero net impact on the Victorian Brolga population.

Offsetting impacts to achieve zero net impact

The scale of offsets are chosen to, at the very least, match the predicted increased mortality from collision risk modelling of the proposed wind farm. Offsets which can be quantified are preferred to give greater confidence in achieving zero net impact. However, any quanitifiedbenefits of offsets are inferred from overseas crane studies.

Mitigation of powerline collisions

This aims to offset predicted Brolga mortality by reducing background (not new) powerline collision risk. Powerlinecollision rates are derived using anecdotal local data and published data from other crane studies (eg Sundar & Choudhury 2005).

The value of powerline marking in reducing rates of collision are derived from other studies (eg Brown & Drewien 1995, Alonso et al. 1995).

Enhancement of breeding success

Brolgas are long-lived birds with low recruitment so a substantial increase in recruitment is required to offset increased adult mortality.

No data exist to quantify increased recruitment arising from breeding site enhancements, although there is considerable qualitative knowledge (Herring 2005).

Stockyard Hill

proposed wind farm

Victorian Brolga Research

Current research is increasing our understanding of seasonal movements and spatial requirements of Brolgas. This work will be used to better avoid and minimise potential impacts of wind farm development on Victoria’s Brolgas.For more information see www.victorianbrolgastudy.com.au

South west Victoria