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March 2008

Avian and Bat Interactions With Turbines Overview of Methods and Results. March 2008. Dale Strickland Western EcoSystems Technology, Inc. Cheyenne, Wyoming. History of the Avian/Wind Turbine Issue. Altamont Pass, CA 7000+ turbines (now ~5400)

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March 2008

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  1. Avian and Bat Interactions With Turbines Overview of Methods and Results March 2008 Dale Strickland Western EcoSystems Technology, Inc. Cheyenne, Wyoming

  2. History of the Avian/Wind Turbine Issue • Altamont Pass, CA • 7000+ turbines (now ~5400) • various designs (lattice towers, guyed towers, vertical axis turbines, downwind turbines, above ground power lines) • high number of raptor fatalities discovered • (Orloff and Flannery 1992, Smallwood and Thelander 2004) • golden eagles (30-70 fatalities per year) • red-tailed hawks (300-500 fatalities per year) • American kestrels (several hundred) • Burrowing owls (50-100 per year) Result: New wind plants often heavily scrutinized

  3. 1.5 MW turbine 100 kW turbine Not exactly to scale

  4. Fatality Monitoring Studies Hopkins Ridge, WA CombineHills, OR Searsburg, VT NPPD Ainsworth, NE Condon, OR Top of Iowa Algona Iowa High Winds, CA Meyersdale, PA Somerset, PA NWTC, CO Altamont, CA Diablo Winds, CA Montezuma Hills, CA Tehachapi Pass, CA San Gorgonio, CA New Project since NWCC 2001 Summary Data reported in NWCC 2001 Summary Additional data collected since NWCC 2001 Summary WEST, Inc.

  5. Doves/Pigeons Gamebirds Other Birds Passerines Rails/Coots Raptors/Vultures Shorebirds Unidentified Birds Waterbirds Waterfowl Sites: BM, Mo, BR, T of I, Condon, WI, NC, SL, Van, FCR, NWTC, and Ponnequin WEST, Inc.

  6. All Birds Agriculture Ag / Grass / CRP Forest Grass / Steppe Wind Project WEST, Inc.

  7. Raptors Agriculture Ag / Grass / CRP Forest Grass / Steppe Wind Project WEST, Inc.

  8. Most sites in the west have measures of raptor use • 12 of these sites have some measure of fatality

  9. Raptor Use Raptor Fatality Facilities High Winds Diablo Winds Hopkins Ridge Klondike Klondike II Stateline Nine Canyon Foote Creek Rim Vansycle Buffalo Ridge Combine Hills Range: 0 – 0.14/MW/yr WEST, Inc.

  10. FOOTE CREEK RIM WYOMING Predictions of high raptor mortality, including golden eagles Other confounding factors

  11. Modeling • “All models are wrong, some are useful, and we should seek those out” • Modeling is an art, not a science

  12. Visualization of Avian Interaction Zones Windfarm Flight Zone Over-flight Fatality Risk Strike Zone Fly-thru Rotor Zone

  13. A Simple Stick Collision Model w deg/sec Stick Bird L 120 Degrees Velocity = v Bird passage time through the rotor: tp=L/V=Length speed ratio (sec) Blocked Sector of Turbine Rotor: B =tp w (deg) Probability of collision: Pc =Blocked Area/Disk Area Pc =3B/(360deg) Pc=3(L/V){w(deg/sec)/360deg} To account for avoidance: Pc=3 A (L/V){w(deg/sec)/360deg} <1 for avoidance where A = 1 for no behavior >1 for attraction Stick Turbine

  14. Modeled Fatality Estimates Collision Factors P1: Pr. of Flying at or Below Maximum Tip Height - Radar Study P2: Pr. of Encountering Swept Area, if flying at Swept Area Height - Area Calc./Simulation P3: Pr. of Collision if Encountering Swept Area - Tucker Model P4: Pr. of Turbine Operating During Migration - Wind Turbine Operators P5: Non-Avoidance Probability - Who knows P6: Pr. a bird passing over WRA collides with a turbine - Multiply Factors Above B: # birds passing over site - Radar Study P6*B: Estimated # of kills WEST, Inc.

  15. Comparison of Spring Target Rates and Migrant Fatality Rates • Three wind projects have conducted both fatality monitoring and radar studies for nocturnal migrants: Buffalo Ridge, MN Nine Canyon, WA Stateline, WA/OR

  16. Stateline Buffalo Ridge Nine Canyon Parameter OR/WA MN WA Spring Nighttime Surveillence Radar Data sampling dates 3/15 - 5/15/01 3/26 – 5/12/96 3/15 - 5/15/01 Targets/hr/2.8 km (March 15 - May 15) 140 260 273 Estimated % of targets below 100 m 13.0 % not collected 14.4 % Width of WRA (km) 16 27 2.4 Estimated Spring Night Target Passage Rate 576,000 1,805,143 168,480 Spring Nighttime Migrant Fatality Data Estimated Spring Nighttime Fatalities 34 104 6 Fatality Rate / Target Passage Rate < 0.0 1 % <0.01 % <0.01% Comparison of Spring Target Rates and Migrant Fatality Rates Major Assumptions: (1) 1 target = 1 migrating bird, (2) no detection bias, (3) targets counted are migrating birds

  17. Nocturnal Migrant Risk • In U.S. studies, consistently most of the nocturnal migrants from radar studies observed over 500 ft • No large mortality events documented at wind projects • Still belief or concern over migrant mortality in bad weather or near stopover sites

  18. If they are studied, you will find themBats found at all wind projects studied

  19. Bat Species Involved photos: J.S. Altenbach *Source: Johnson, G.D. 2005. A review of bat mortality at Wind-energy developments in the United States. Bat Research News 46:45-49.

  20. Bat Fatalities • 21 studies at 19 facilities • 5 regions in US and Canada • 0.9 – 53.3 bats/MW • Highest fatalities in the east with exception of recent event in Alberta • 11 of the 45 species occurring in US • Heavily skewed to migratory foliage roosting species (hoary, eastern red, silver-haired bats) • Little data from SW where Brazilian free-tailed bat most abundant

  21. Infrared Image of a Bat Flying Through a Wind Turbine Rotor Multi-Stakeholder Wildlife Research • National Wind Coordinating Committee • Bat & Wind Energy Cooperative (BWEC) • Grassland Shrub Steppe Species Collaborative Photo by Jason Horn, Boston University

  22. Why are they colliding? • Hypotheses (Arnett et al; Kunz et al) • Following linear corridors • Echolocation fails to detect turbines • Attracted to altered landscapes • Attracted to insects around turbines • Attracted to turbine sounds • Attracted to turbines as roosts • Attracted to magnetic fields • Bats experience decompression near blades • Thermal inversions bring them into blade range • Other ideas (Cryan, unpublished) • Behaviorally programmed to gravitate toward and loiter around the tallest “trees” along their migration route as a simple way of rendezvousing, and perhaps mating, with others of their kind

  23. Habitat Impacts Habitat Impacts WEST, Inc.

  24. Sources of Habitat Impact Direct loss of habitat Turbine pads, roads, substations, transmission lines Indirect loss of habitat from behavioral response to wind plant facilities Turbines, transmission lines, roads, human activity Long-term impacts Permanent structures and/or avoidance with no habituation Short-term impacts Construction, restoration and/or habituation WEST, Inc.

  25. Predicted Impacts Due to Habitat Disturbance • Temporary (construction) impacts from roads, pads, substation, etc. (estimated) • 0.4 to 3 acres/turbine • Permanent (operations) impacts (estimated) • 0.7 to 1 acres/turbine • Impacts and Reclamation success due to • Turbine type • Site characteristics • Reclamation plan • Climate • Permanent footprint 5-10% of site (BLM 2005) WEST, Inc.

  26. Displacement Studies • Field studies impacts of wind turbines absent for most species but impacts are likely (EXO et al. 2003) • Grassland Songbird Displacement Studies • Buffalo Ridge, MN (Leddy 1999, Johnson et al. 2000): Small scale displacement (~80-100m) • South Dakota: 1 of 3 species (grasshopper sparrow) showed reduced density within 150m in South Dakota (Schaffer and Johnson 2007) • Stateline: Grasshopper sparrow showed displacement effect within 50m • Oklahoma: No displacement for grassland species as a group (O’Connell and Piorkowski 2006) • Ongoing and potential studies of bird displacement (e.g., Stateline, N & S Dakota, and prairie chicken in Kansas) WEST, Inc.

  27. Other Bird Species • Mountain Plover – Foote Creek Rim, WY declined at wind plant, a reference area, and regionally • Canada geese – Top of Iowa no displacement in corn fields • Europe • Some species unaffected while certain waterfowl, shorebirds, and songbirds avoid turbines (e.g., European golden plover, northern lapwing, Eurasian curlews) • Pink-footed goose displaced up to 600m WEST, Inc.

  28. Avoidance Behavior is Significant day = c. 3000m night = c. 1000m Radar Tracks of Migrating Birds through Nysted Offshore Windfarm for Operation in 2003 Response distance: WEST, Inc.

  29. Summary - Birds (based on existing studies at the current level of development) • With the possible exception of Altamont, avian risk from individual wind projects is a risk to individual birds and not populations • Preliminary information suggests avian abundance is important factor in risk, although species behavior, technology and landscape are contributing factors • Wind turbine lights not currently documented as a significant attractant for birds • Effectiveness of deterrent measures uncertain • Major concern over offshore impacts is displacement, although fatalities have not been adequately evaluated WEST, Inc.

  30. Summary - Bats • Fewer studies of pre-construction bat or migrant use and post-construction fatality • Predictability very uncertain because of a lack of good method for estimating exposure • Limited fatality studies suggest fatalities are primarily migratory tree-roosting bats • Highest fatalities in the east with exception of recent event in Alberta • Relatively high fatalities of Brazilian free-tailed bat in Oklahoma suggest this species may be at similar risk to tree-roosting bats • Cause and cure uncertain • Some mitigation measures show promise but must be evaluated WEST, Inc.

  31. Summary - Habitat • Estimated direct habitat impacts are relatively small for birds • Displacement of grassland nesting birds is likely but the magnitude is uncertain and may range from near 0 to several hundred meters for song birds and even greater for other species (e.g., nesting effects may be much larger for prairie grouse) • Wind project (macro) and wind turbine (micro) siting believed to be best way to minimize impacts • Mitigation measures poorly evaluated • Cumulative impacts poorly understood • Data better for wind than other sources of impact WEST, Inc.

  32. Priority Research Needs • Better synthesis of existing information • Fatalities and habitat-related impacts in unstudied and new locations and unstudied species are needed • Estimation of exposure for nocturnal migrating passerines and bats • Habitat fragmentation and cumulative impacts • Models for prediction of impacts and risk • Determine mitigation effectiveness • Cumulative impacts - linkage of fatality and non fatality impacts to population dynamics and biological significance WEST, Inc.

  33. Questions?

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