Ecological Impacts of Wind Farms: Global Studies. Are Wind Farms Hazardous to Birds and Bats? Stephen J. Ambrose

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1 Ecological Impacts of Wind Farms: Global Studies Are Wind Farms Hazardous to Birds and Bats? Stephen J. Ambrose

2 Impact Phases Construction Phase: Habitat clearance Disturbances (noise, visual, dust etc.) Operational Phase Direct mortality (birds & bats) Changes in food abundance (e.g. aerial insects)

3 Construction Impacts: The UK Experience (Birds) Degree of disturbance depends on: Number of turbines. Bird species present at the site. Seasonal patterns of habitat use. Availability of alternative habitat.

4 Construction Impacts: The UK Experience (Birds) Extent of disturbance around wind farm varies according to species: Grassland songbirds: 80 m Waterfowl: 800 m Seabirds: 4 km (4000 m) Zone of disturbance often reported: 600 m

5 Construction Impacts: The UK Experience (Birds) The nature & magnitude of construction impacts depend on sensitivity of species to disturbances and their resilience to habitat modification. Decrease in population densities of timid species in wind farm areas due to disturbances (Red Grouse, Snipe & Curlew) Increase in population densities of species which favour open swards (expanses of short grass) (Skylarks, Meadow Pipits & Stonechats) Decrease in population densities of species which favour tall grasses and/or shrubs (Wheatear) No significant impacts on other species studied (Golden Plover, Lapwing, Dunlin)

6 Greater impacts of UK wind farms on bird populations during construction than subsequent operation Journal of Applied Ecology Volume 49, Issue 2, pages MAR 2012 DOI: /j x

7 Operational Impacts: Direct Mortality Wind turbines can kill birds and bats. Bird groups most at risk in Northern Hemisphere: Migrating songbirds (~ 75% of mortalities at US wind facilities). Raptors (esp. on migration & in foraging areas). Migrating waterfowl (turbines near wetlands). Migrating shorebirds (marine & shoreline turbines). Mortality varies widely across regions and wind resource areas.

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9 Flocking Bramblings in Berne, Switzerland about to start autumn migration

10 Raptors on migration in Cadiz, Spain

11 Start of autumn shorebird migration in Alaska.

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13 Why do Birds Collide with Wind Turbines? Location of wind farms along major migratory routes (strong wind areas). Inclement weather (e.g. heavy fog) Nocturnal migration. Bird abundance, e.g. more raptor fatalities as raptor abundance near turbines increases.

14 Why do Birds Collide with Wind Turbines? Some species that forage close to turbines (e.g. Red-tailed Hawks, Golden Eagles) more susceptible to collisions. Other aerial soarers (e.g. corvids) appear to avoid collisions with turbines.

15 Bat Mortality at Northern Hemisphere Wind Farms North-western Europe (bats/turbine/year): Flat, open inland farmland: 0-3 In more complex agricultural farmland: 2-5 On coast & forested hills & ridges: Germany ~ 200,000 bats/year, depressing bat populations up to 3,300 km away. Spain: bats/turbine/year United States: 0 to 40 bats/mw/year

16 Possible Causes of Bat Mortality at Wind Turbines Proximate Causes (causes of death) Collisions with towers & rotating blades. Barotrauma?

17 Lung Damage in Bats (Barotrauma?)

18 Possible Causes of Bat Mortality at Wind Turbines Ultimate Causes (why bats collide with turbines) Random Collisions (i.e. due to chance). Coincidental collisions (spatial, temporal & demographic variation). Weather-dependent: most fatalities occur on nights with low wind speed & typically before & after the passage of storm fronts. Bats are attracted to turbines (tree roosting spp. & foragers of aerial insects).

19 King Island Bats Lesser Long-eared Bat (Nyctophilus geoffroyi) Gould s Wattled Bat (Chalinolobus gouldii)

20 Mitigation Measures 1. Pre-development site evaluation (EIA): Will there be impacts to birds and bats at levels of concern? What sites should be avoided? How can the wind farm be designed & operated to lessen impacts? 2. Locate wind farms in flat, open agricultural landscapes rather than near important bird & bat habitats

21 3. Curtailment: Mitigation Measures Increase cut-in speed of turbines during low-wind periods (when bats are most active). 4. Feathering: Swivelling rotor blades on a bearing to decrease angle of wind attack and hence their lift. 5. Use of radar to detect large bird migrations near wind farms.

22 Turbine in Feathered Condition at a Canadian Wind Farm

23 Example of a portable radar station

24 Use of Radar to Detect Mass Bird Migration

25 Mitigation Measures 6. Shorter turbine heights? Shorter turbines & narrower, shorter blades = smaller sweep areas = smaller blade-tip vortices and = less blade-wake turbulence. 7. Making turbines more visible : Ultraviolet paint Flashing red lights

26 Mitigation Measures 8. Purple wind turbines attract significantly fewer insects than white or light grey ones. 9. Does wildlife become habituated to wind farms? Need for further study.