1. Bird Fatalities in the Altamont Pass Wind Resource Area U.S. Fish and Wildlife Service Sacramento, CA 28 January 2004

2. Acknowledgements ● This research was funded by the California Energy Commission (Linda Spiegel, Project Manager) and by NREL, the National Renewable Energy Laboratory, (Karin Sinclair, Project Manager). ● Access to turbines and logistical support was generously provided by FORAS, EnXco, Altamont Wind Power, Green Ridge Services/AIC, and SeaWest.

3. Background to the Problem ● Small-scale wind program in the APWRA in early to mid 1970s. ● In 1980, a CEC biologist identified bird kill problem in APWRA. ● Paper presented by CEC at 1988 AWEA annual meeting drew attention. ● By 1990, several studies initiated; 3,000+ turbines installed by then. ● Early 1990s, Kenetech convenes Avian Research Task Force Several large-scale research projects initiated. 1993 bankruptcy forces cessation of studies. No solutions to problem identified. ● 1989 to mid-1990s, Orloff and Flannery conducted first in-depth studies of bird fatalities in the APWRA. Funded by the CEC. ● From 1994-97, NREL funded large-scale golden eagle study by Dr. Grainger Hunt et al. CEC funded continuation until 2002. ● In 1998, NREL funded BRC/Thelander for fatalities and behavior research. In 2001, the CEC funded the current, expanded effort.

4. Our Objectives ● Study relationships between bird behaviors (e.g., flight, perching, foraging) and fatalities. ● Quantify bird fatalities to better understand the scope of the problem, and to develop a large sample size representative of most of the APWRA. ● Develop quantitative model for use as a tool by the wind industry to help reduce bird fatalities. Model to be based on relationships identified between bird kills and landscape features and topography, land use practices, raptor prey species numbers and distribution, turbine types and infrastructure configurations, or any other factors that appear associated with bird fatalities.

5. 181141161158167197183127166180185111N = 5 4 3 2 1 DecNovOctSepAugJulJunMayAprMarFebJan Wind Speed Beaufort Scale, mean & 95% CI per session

6. 171136144138128153151104147163174105N = 1.0 0.8 0.6 0.4 0.2 0.0 DecNovOctSepAugJulJunMayAprMarFebJan Proportion of turbines operating during behavior observation sessions

7. 4711217830536235532134N = 76543210 1.0 0.8 0.6 0.4 0.2 0.0 Wind Speed (Beaufort Scale) Proportion of turbines operating during behavior observation session

8. 69197334674782839 34N = 100 80 60 40 20 0 76543210 Distance of raptors to nearest turbine Mean & 95% CI per session Wind speed on Beaufort scale Meters It appears that raptors can perceive the difference between operating and non-operating turbines.

9. ● 1,958 behavioral observation sessions (two-person team) ● 48,396 bird sightings ● Birds observed in 91% of sessions ● 31,317 minutes of bird activity ● 13,725 minutes spent flying (44%) ● 17,592 minutes spent perching (56%) ● 25,960 minutes of raptor activity ● 11,988 minutes raptors spent flying (46%) ● 13,972 minutes raptors spent perching (54%) Summary Behavior Statistics (1998-2000 data only)

10. 100806040200 120 110 100 90 80 70 60 50 40 30 20 10 0 Number of fatalities found in behavior plots only Percentage of flights within 50 m of turbines within the height domain of the rotor swept area Burrowing owl Western meadowlark Rock dove Red-tailed hawk There is no significant relationship between fatalities and observations of flights <50m from turbines. Burrowing owls tended to perch away from turbines.

11. Species Number of minutes observed perching on wind turbine/tower that is: OperatingNot operatingBrokenTotal Turkey vulture0000 Golden eagle0260 Red-tailed hawk1054065624232 Northern harrier0101 Prairie falcon0140 American kestrel5594071002 Burrowing owl0560 Common raven6399091062 European starling24011964411877 House finch072950 Loggerhead shrike41810185 Rock dove265726109 Western meadowlark72240231 Horned lark0000 Total5001957162320694 Perching on Wind Turbines

12. Proximity Zone based on distance to nearest turbine (m) Observed ÷ Expected Minutes of Flight Golden eagle Red-tailed hawk Northern harrier Prairie falcon American kestrel Burrowing owl 0-50 51-100 101-300 0-50 51-100 101-300 0-50 51-100 101-300 0-50 51-100 101-300 0-50 51-100 101-300 0-50 51-100 101-300 131211109876543210 Some species spend far more time than expected by chance close to turbines.

13. Search Methods 50 meters One observer per side of turbine string Level terrain Steep terrain wind turbine

14. ● 1,526 turbines in 182 strings sampled March 1998-Sept 2002 (= Set 1) ● 2,538 turbines in 308 strings sampled November 2002 – May 2003 (= Set 2) ● Averaged 7+ fatality searches per year per turbine/string ● Searched only 50 meters on each side of turbines (i.e., applied detection factor) ● 1,161 fatalities found, with 198 of these estimated at >90 days old and excluded from rate calculations (see Table 1 handout). ● 46+ bird species and 1 bat species represented. APWRA-wide annual fatality estimates 1 for selected species (see Table 2 handout): ● Golden Eagles = 76 – 116 deaths per year ● Red-tailed Hawks = 209 – 300 deaths per year ● Burrowing Owls = 99 – 380 deaths per year ● All birds = 1766 – 4721 deaths per year ● Raptors = 881 – 1300 deaths per year 1 Low values adjusted for search detection. High values adjusted for search detection and scavenging. Some Bird Fatality Facts

15. What do the number of bird fatalities and their distribution tell us about the underlying causes, and any possible solutions?

16. Cattle spend a disproportionate amount of their time under wind turbines.

17. BRC biologists found the stomachs of freshly killed red-tailed hawks filled with grasshoppers. Grasshoppers are a major food source for American kestrels and burrowing owls during much of the year (late summer and fall, mainly). They eat cow dung.

18. Construction and maintenance practices at turbines has resulted in disproportionate numbers of burrowing mammals being present near turbines than away from turbines.

19. Wind farms create a lot of lateral and vertical edge, preferred habitat for gophers and other burrowing mammals.

20. Turbine pads provide suitable burrowing sites for cottontails, a preferred prey species for golden eagles and other large raptors.

21. Rock Piles Near Turbine Strings and Fatalities 3.53.02.52.01.51.00.50 None ≤0.25/turbine >0.25/turbine None ≤0.25/turbine >0.25/turbine None ≤0.25/turbine >0.25/turbine Burrowing owl Barn owl Great horned owl P < 0.005 ns 39 6 14 13 9 4 5 2 None ≤0.25 rock piles/turbine >0.25rock piles/turbine None ≤0.25/turbine >0.25/turbine None ≤0.25/turbine >0.25/turbine Golden eagle Red-tailed hawk American kestrel P < 0.005 P < 0.05 0.10 > P > 0.05 12 6 1 13 4 77 23 17 3.53.02.52.01.51.00.50 Observed ÷ Expected Number of Fatalities

22. Turbine Position in String and Behaviors Orange refers to inadequate sample size. Most raptors spent disproportionate amount of flight time near ends of turbines and near gaps, except for burrowing owls.

23. Turbine Position in String and Fatalities 2.01.51.00.50 End Interior Gap End Interior Gap End Interior Gap Burrowing owl Barn owl Great horned owl 29 25 7 10 18 4 3 8 1 P < 0.005 ns End Interior Gap End Interior Gap End Interior Gap Golden eagle Red-tailed hawk American kestrel 8 18 4 8 8 3 38 76 17 0.10 > P > 0.05 ns 2.01.51.00.50 Observed ÷ Expected Number of Fatalities

24. Windwall Presence/Absence and Behaviors Observed ÷ Expected Minutes of Flight that came to within 50 m of turbine Golden eagle Red-tailed hawk Northern harrier Prairie falcon American kestrel Burrowing owl Yes No Yes No Yes No Yes No Yes No Yes No 2.01.51.00.50 0.10 > P > 0.05 Observed ÷ Expected Minutes of Perching on turbine Yes No Yes No Yes No Yes No Yes No 2.01.51.00.50 Golden eagle Red-tailed hawk Prairie falcon American kestrel Burrowing owl ns

25. Tower Type and Fatalities 2.52.01.51.00.50 Vertical axis Tubular Lattice Vertical axis Tubular Lattice Vertical axis Tubular Lattice Burrowing owl Barn owl Great horned owl 10 36 16 3 17 13 3 9 P < 0.005 ns Vertical axis Tubular Lattice Vertical axis Tubular Lattice Vertical axis Tubular Lattice Golden eagle Red-tailed hawk American kestrel 1 11 18 15 4 3 68 60 P < 0.005 P < 0.05 ns 2.52.01.51.00.50 Observed ÷ Expected Number of Fatalities

26. 3.53.02.52.01.51.00.50 Out of canyon In canyon Out of canyon In canyon Out of canyon In canyon Burrowing owl Barn owl Great horned owl P < 0.005 ns 47 15 18 15 11 1 Out of canyon In canyon Out of canyon In canyon Out of canyon In canyon Golden eagle Red-tailed hawk American kestrel P < 0.005 ns 26 4 8 11 94 37 3.53.02.52.01.51.00.50 Observed ÷ Expected Number of Fatalities Canyon Effect and Fatalities

27. Rodent Control and Fatalities 2.52.01.51.00.50 Burrowing owl Barn owl Great horned owl None Moderate Intense None Moderate Intense None Moderate Intense 10 36 16 18 15 5 1 6 P < 0.005 0.10 > P > 0.05 ns Golden eagle Red-tailed hawk American kestrel None Moderate Intense None Moderate Intense None Moderate Intense 4 9 17 3 14 2 17 58 56 P < 0.005 0.10 > P > 0.05 ns 2.52.01.51.00.50 Observed ÷ Expected Number of Fatalities Note: used since 1997, except at SeaWest

28. Rodent Control Program Observations ● In the absence of a rigorous BACI study design, conclusions as to the effectiveness of rodent control efforts cannot be made. But…. 1 Since rodent control began, we would expect to see disproportionately greater raptor mortality in areas where no rodent control was applied. This was not the case, except for great horned owls. 2 Disproportionately more golden eagles, red-tailed hawks, and burrowing owls were killed at turbines located where rodent control was applied. 3The rodent control program effectively reduced ground squirrel densities, but pocket gophers increased. Also, the degree of clustering of pocket gophers at turbines increased substantially with rodent control. We believe that foraging raptors will detect areas of increased burrowing activity, and thus be attracted to high risk areas. ● Based on these and other observations, we suspect that the rodent control program has been counter-productive.

29. 200220001998199619941992199019881986 0.3 0.2 0.1 0.0 Bird and Raptor risk index (Mortality ÷ # individuals reported/hour) Year of Estimate (median year used for multi-annual studies) Raptors All birds Bird use has been lower in recent year than was reported in previous studies. Therefore, risk per raptor using the APWRA appears to be greater.

30. ● Danger increased with taller towers, larger rotor diameters, and slow to intermediate tip speeds. Turbines with lower blade reaches were most deadly to golden eagles. ● Perch availability on towers appears less important than previously believed. ● Turbines on steeper slopes and in canyons were generally more dangerous to raptors, but ridge crests and peaks within canyons were also dangerous. Some Key Observations ● The presence of rock piles near turbine laydown areas is associated with greater raptor mortality. ● Fatality associations are usually species-specific, so solutions for one species might not serve as solutions for others.

31. Con’t. ● Windwalls appeared to be relatively safer for raptors; Raptors were killed disproportionately by turbines that were less crowded by other turbines. ● Although rodent control reduced rodent numbers overall, it also increased the degree of clustering around turbines of remaining pocket gophers and desert cottontails ● Rodent control failed to reduce raptor mortality. The spatial distribution of fossorial animal burrows appeared more important than their abundance in associating with raptor mortality at wind turbines. ● Raptor mortality differs by season. Summer and winter seasons have highest mortality.

32. ● Discontinue the rodent control program. ● Promote small mammals away from wind turbines, and discourage them near wind turbines by reducing lateral and vertical edges. ● Allow vegetation to grow tall near wind turbines so that small mammals are less visible to raptors near turbines; Subsequently, burrowing owls might reside farther from turbines. ● Prevent cattle from congregating at wind turbines. ● Move rock piles away wind turbines, or get rid of them. ● Relocate existing wind turbines away from canyons, or decommission them. ● Isolated wind turbines should be relocated and clustered up with groups of other wind turbines. Suggested Mitigation Measures or Operating Practices

33. ● Use more windwall configurations and clustering of turbines. ● Remove derelict and non-operating turbines, or lay down derelict towers. ● Test the Hodos painting scheme in the field. Apply selectively if useful tool. ● Modify wind turbines at the ‘edge’ of the wind farm and at the ends of turbine rows to divert bird flights. Useful application for Hodos painting scheme, if proven effective. ● Erect benign physical structures to divert birds away from the ends of turbine rows, and/or experiment with strategically placed raptor perches. ● Retrofit all power poles to be raptor-safe (APLIC compliance standards). ● Replace the currently used WRRS monitoring program for bird fatalities with one that is more scientifically rigorous and is performed independently. ● Compensate with off-site mitigation those impacts that cannot be avoided or reduced. Con’t.

34. 1- BRC to submit report of findings to CEC in Feb 2004. BRC’s NREL comprehensive report currently under review. 2- Prioritize and select ‘best’ fatality reduction techniques for field-testing and monitoring. BRC/CEC prepare initial draft Work Plan for agency and operator’s review(?) 3- Design controlled experiments to test effectiveness of various measures at reducing fatalities using BACI approach. 4- Decide which species to focus mitigation and/or experiments on. 5- Report on effectiveness experiments and consider widespread application on case-by-case basis. 6- Design and conduct controlled experiment(s) to determine the effects of the repowering program on bird mortality. 7- Need to use number of kills per MW per turbine per unit of time in future mortality calculations, experiments, etc., and not simply number of fatalities/turbine/year. Requires output data from turbine operators. BRC describes benefits of this metric at length in upcoming report and paper. Where Do We Go From Here?

35. What Are Some Examples of Needed Experiments or Monitoring? 1- Design monitoring program to compare any changes in bird mortality, especially for raptors, associated with the repowering program at sites with historical fatality data. 2- Design treatment/control experiment to evaluate effectiveness of placing benign structures (several types, settings?) at the ends of turbine strings where kill rates have historically been high. 3- Design treatment/control experiment to evaluate effectiveness of modifying grassland management practices to reduce prey populations, or their visibility/vulnerability to raptor predation. 4- Design experiment to test the effect on raptor mortality of various (non- lethal) manipulations of prey population distributions and abundances at varying distances from turbines strings with historically high raptor mortality, e.g., increase prey populations away from turbines.

36. More examples… 5- Field test the effectiveness of the Hodos et al painting scheme as a tool to reduce fatalities in a location and setting that takes advantage of historical fatality data. 6- Remove rock piles and monitor for changes in bird mortality. 7- Design some control and treatment experiments excluding cattle from congregating at turbine strings and document the effects on prey availability, bird use, and fatalities. 8- Conduct a two-year study of burrowing owl population dynamics in the APWRA, and the effects of wind turbine fatalities. 9- Experiment with various environmentally-safe means of selectively and permanently removing raptor prey species from around turbine strings.

37. # ≥1 death/MW/year # 0.01-0.99 deaths/MW/year # 0 deaths recorded Burrowing Owl Mortality

38. # ≥1 death/MW/year # 0.01-0.99 deaths/MW/year # 0 deaths recorded Red-tailed Hawk Mortality

39. # ≥1 death/MW/year # 0.01-0.99 deaths/MW/year # 0 deaths recorded Golden Eagle Mortality