201308ppt1 (King Island Workshop, 20 May 2013)

Ecological Impacts of Wind Farms:Ecological Impacts of Wind Farms:Global StudiesGlobal Studies

Are Wind Farms Hazardous toBirds and Bats?Stephen J. Ambrose

Impact PhasesImpact Phases

Construction Phase:

Habitat clearance

Disturbances (noise, visual, dust etc.)

Operational Phase

Direct mortality (birds & bats)

Changes in food abundance(e.g. aerial insects)

Construction Impacts:Construction Impacts:The UK Experience (Birds)The UK Experience (Birds)

Degree of disturbance depends on:

Number of turbines. Number of turbines.

Bird species present at the site.

Seasonal patterns of habitat use.

Availability of alternative habitat.


Extent of disturbance around windfarm varies according to species:

Grassland songbirds: 80 mGrassland songbirds: 80 m

Waterfowl: 800 m

Seabirds: 4 km (4000 m)

Zone of disturbance often reported:600 m


The nature & magnitude of construction impacts dependon sensitivity of species to disturbances and theirresilience to habitat modification.

Decrease in population densities of timid species in windfarm areas due to disturbances(Red Grouse, Snipe & Curlew)(Red Grouse, Snipe & Curlew)

Increase in population densities of species which favouropen swards (expanses of short grass)(Skylarks, Meadow Pipits & Stonechats)

Decrease in population densities of species which favourtall grasses and/or shrubs (Wheatear)

No significant impacts on other species studied(Golden Plover, Lapwing, Dunlin)

Greater impacts of UK wind farms on bird populations duringGreater impacts of UK wind farms on bird populations duringconstruction than subsequent operationconstruction than subsequent operation

Journal of Applied EcologyVolume 49, Issue 2, pages 386-394 13 MAR 2012 DOI: 10.1111/j.1365-2664.2012.02110.xhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2012.02110.x/full#f1

Operational Impacts: Direct MortalityOperational Impacts: Direct Mortality

Wind turbines can kill birds and bats.

Bird groups most at risk in Northern Hemisphere:

Migrating songbirds (~ 75% of mortalities atUS wind facilities).

Raptors (esp. on migration & in foraging areas). Raptors (esp. on migration & in foraging areas).

Migrating waterfowl (turbines near wetlands).

Migrating shorebirds (marine & shorelineturbines).

Mortality varies widely across regions and windresource areas.

FlockingFlocking BramblingsBramblings in Berne, Switzerlandin Berne, Switzerlandabout to start autumn migrationabout to start autumn migration

Raptors on migration in Cadiz, SpainRaptors on migration in Cadiz, Spain

Start of autumn shorebirdStart of autumn shorebirdmigration in Alaska.migration in Alaska.

Why do Birds Collide withWhy do Birds Collide withWindTurbines?WindTurbines?

Location of wind farms along majormigratory routes (strong windareas).

Inclement weather (e.g. heavy fog)

Nocturnal migration.

Bird abundance, e.g. more raptorfatalities as raptor abundance nearturbines increases.

Why do Birds Collide withWhy do Birds Collide withWindTurbines?WindTurbines?

Some species that forage close toturbines (e.g. Red-tailed Hawks,Golden Eagles) more susceptibleto collisions.

Other aerial soarers (e.g. corvids)appear to avoid collisions withturbines.

Bat Mortality at NorthernBat Mortality at NorthernHemisphere Wind FarmsHemisphere 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: 5 – 20.On coast & forested hills & ridges: 5 – 20.

Germany~ 200,000 bats/year, depressing bat populations

up to 3,300 km away.

Spain: 200-670 bats/turbine/year

United States: 0 to 40 bats/MW/year

Possible Causes of Bat MortalityPossible Causes of Bat Mortalityat WindTurbinesat WindTurbines

Proximate Causes (causes of death)

Collisions with towers & rotating Collisions with towers & rotatingblades.

Barotrauma?

Lung Damage in BatsLung Damage in Bats((BarotraumaBarotrauma?)?)

Possible Causes of Bat MortalityPossible Causes of Bat Mortalityat WindTurbinesat WindTurbines

Ultimate Causes (why bats collide with turbines)

Random Collisions (i.e. due to chance).

Coincidental collisions (spatial, temporal &demographic variation).

Coincidental collisions (spatial, temporal &demographic variation).

Weather-dependent: most fatalities occur onnights with low wind speed & typically before &after the passage of storm fronts.

Bats are attracted to turbines tree roosting spp. &foragers of aerial insects).

King Island BatsKing Island Bats

Lesser Long-eared Bat(Nyctophilus geoffroyi)

Gould’s Wattled Bat(Chalinolobus gouldii)

Mitigation MeasuresMitigation Measures

1. Pre-development site evaluation (EIA):

Will there be impacts to birds andbats at levels of concern?

What sites should be avoided? What sites should be avoided?

How can the wind farm be designed &operated to lessen impacts?

2. Locate wind farms in flat, openagricultural landscapes rather than nearimportant bird & bat habitats


3. Curtailment:

Increase “cut-in speed” of turbinesduring low-wind periods (when batsare most active).

4. Feathering:4. Feathering:

Swivelling rotor blades on a bearing todecrease angle of wind attack and hencetheir lift.

5. Use of radar to detect large birdmigrations near wind farms.

Turbine in “Feathered Condition”Turbine in “Feathered Condition”at a CanadianWind Farmat a CanadianWind Farm

Example of a portable radar stationExample of a portable radar station

Use of Radar to Detect MassUse of Radar to Detect MassBird MigrationBird Migration


6. Shorter turbine heights?

Shorter turbines & narrower, shorter blades

= smaller sweep areas

= smaller blade-tip vortices and= smaller blade-tip vortices and

= less blade-wake turbulence.

7. Making turbines more “visible”:

Ultraviolet paint

Flashing red lights


8. Purple wind turbines attractsignificantly fewer insects than whiteor light grey ones.

9. Does wildlife become habituated towind farms? Need for further study.

201308ppt1 (King Island Workshop, 20 May 2013)

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