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Bird Years 2005–2010
Altamont Pass Wind Resource Area Bird Fatality Study
December 2012
Prepared for:
Alameda County Community Development Agency
M94
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Distribution and Abundance of Turbine Types
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Distribution of Turbines Monitored, 2005–2009 BYs
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Distribution of Turbines Monitored, 2010 BY
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Distribution of OPs Surveyed,2005–2010 BYs
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Changes in Installed Capacity, 2005–2010
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Search Effort and Average Search Interval (Days ±1 SD), Bird Years 2005–2010
Bird Year Strings Searched Turbines Searched Average Search Interval (Days ± 1 SD)
2005 302 2,118 49.6 (3.49)
2006 340 3,211 35.0 (1.23)
2007 340 3,571 34.5 (0.58)
2008 340 4,090 29.4 (0.50)
2009 334 3,543 33.5 (0.51)
2010 262 1,817 34.1 (1.61)
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Shutdown Type Years November December January FebruaryCrossover 2005 Crossover Crossover Crossover Crossover
Crossover 2006 Crossover Crossover Crossover Crossover
Phased universal 2-month shutdown
2007 Phased Shutdown Phased Phased
Phased universal 3-month shutdown
2008 Phased Shutdown Shutdown Phased
Universal 3-month shutdown
2009 Shutdown Shutdown Shutdown Operating
Universal 3-month shutdown
2010 Shutdown Shutdown Shutdown Operating
Notes:Crossover = Turbines in half of the APWRA were shut down while the other half continued normal operations.Phased = Individual turbine strings were shut down immediately following a search of that string by the MT.Universal = All turbines APWRA-wide were completely shut down simultaneously.
Timing, Duration, and Other Characteristics of the Winter Shutdown of Turbines, Bird Years 2005–2010
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Turbine Removals (Megawatts) in the APWRA, Bird Years 2005–2010Number of Turbines (MW) Removed per Bird Year
2005 2006 2007 2008 2009 2010
Attrition 131 (12) 242 (39) 76 (9) 80 (8) 148 (15) 17 (2)
Tier and Hazardous Turbinesa 0 (0) 23 (2) 100 (10) 106 (11) 55 (6) 18 (2)
Total 131 (12) 265 (41) 176 (19) 186 (19) 203 (21) 35 (4)a Both Smallwood and Spiegel (2005a, 2005b, and 2005c) and the APWRA Scientific Review Committee (2007) identified
turbines in the APWRA to be removed, relocated, or permanently shut down to reduce avian fatalities. These two ranking systems are not mutually exclusive; some turbines identified for removal by Smallwood and Spiegel were also identified by the Scientific Review Committee.
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Base Layer of Operating Group Boundaries (BLOBs)
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Avian Fatalities in the APWRA Excluded from Analysis, BYs 2005–2010
Reason for Exclusion
Number of Fatalities Excluded by Bird Year
Total
Total Fatalities before Exclusion
Total Fatalities after Exclusion2005 2006 2007 2008 2009 2010
Not turbine-related 14 23 29 38 56 15 175 6,133 5,958
WRRS recordsa 46 56 59 61 51 74 347 5,958 5,611
Found beyond 125 meters 1 6 15 4 2 1 29 5,611 5,582Older than 90 days or of undeterminable age
37 75 326 140 145 101 824 5,582 4,758
Unidentifiable or injured birds 0 3 9 11 3 6 32 4,758 4,726
Backdated to 2004 88 n/a n/a n/a n/a n/a 88 4,726 4,638
Total 186 163 438 254 257 197 1,495 6,133 4,638n/a = not applicable.
WRRS = Wildlife Reporting Response System.a Excludes golden eagle records from monitored turbines; these records were retained for analysis.
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SEASONAL CHANGES IN FATALITIES AND BIRD USE AND UNADJUSTED FATALITY RATES
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Average Number of Unadjusted Fatality Detections (±95% CI) per Month
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Average Unadjusted Fatalities per Month (±95% CI) and Bird Use (±95% CI)—Focal Species
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Unadjusted Fatality Rates (Fatalities per MW ±95% CI)—Focal Species, BYs 2005–2010
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DETECTION PROBABILITY ESTIMATES
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Searcher Detection Probabilities for Various Bird Groups in the APWRABird Group Searcher Detection Probability
Medium and large raptors 100%
Medium and large non-raptors 80%
Small raptors 75%
Small non-raptors 51%
Source: Smallwood 2007
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Predicted Proportion of Bird Carcasses Remaining
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QAQC Study
233 Carcasses Used in 233 Trials
29 Species
109 Raptors
Used Wingspan instead of Adjustment Groups
Covered All Seasons
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Number of QAQC Carcass Trials in each of Four Adjustment Groups
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Seasonal Distribution of QAQC Carcass Trials in each of Four Adjustment Groups
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Changes in Searcher Efficiency (and 95% Credible Interval Bands) as Carcasses Age Based on Blind Searches during the QAQC Study for the Four Focal Species
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Changes in Detection Probability (and 95% Credible Interval Bands) Over Time Based on Sequences Conducted during the QAQC Study and Information from the Carcass Removal / Scavenging Study
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QAQC and Modified Smallwood (2007) Detection Probabilities (±95% CI)—Focal Species
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QAQC Derived Estimates of Detection Probability
They are derived from a large number of experimental trials conducted entirely within the local study area, using the same personnel used to search for fatalities.
They are based primarily on carcasses actually killed in the study area, or on carcasses of species known to occur—or are similar to species known to occur—in the study area. The carcasses are also the freshest reasonably available.
They are derived from a composite model that estimates carcass removal and searcher efficiency probabilities simultaneously to account for both variables’ joint dependence on carcass age. The model also accounts for the use of carcasses that are not “fresh” when estimating the removal rate.
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ADJUSTED FATALITY RATES
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Adjusted Fatality Rates (Fatalities per MW ±95% CI) Using QAQC and Modified Smallwood Detection Probabilities—Focal Species, BYs 2005–2010
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3-Year Rolling Averages of Annual Adjusted Fatality Rates (Fatalities per MW and ±95% CI) Based on QAQC and Modified Smallwood (2007) Detection Probabilities―Focal Species, BYs 2005–2010
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Annual Adjusted Focal Species Fatality Rates (Fatalities per Megawatt and 95% CI) Based on QAQC Detection Probabilities, BYs 2005–2010
SpeciesBird Year and Rate (95% CI)
2005 2006 2007 2008 2009 2010American kestrel 0.34
(0.30–0.38)0.58 (0.52–0.63)
0.59 (0.54–0.65)
0.40 (0.36–0.43)
0.37 (0.34–0.39)
0.44 (0.36–0.52)
Burrowing owl 0.53(0.47–0.59)
1.63 (1.49–1.77)
0.59 (0.54–0.64)
0.26 (0.23–0.29)
0.47 (0.43–0.51)
0.42 (0.34–0.49)
Golden eagle 0.08 (0.07–0.08)
0.17 (0.16–0.18)
0.08 (0.07–0.08)
0.05 (0.05–0.05)
0.06 (0.05–0.06)
0.07(0.06–0.08)
Red-tailed hawk 0.62(0.59–0.66)
0.78 (0.73–0.82)
0.39 (0.38–0.41)
0.21 (0.20–0.22)
0.18 (0.17–0.19)
0.45(0.41–0.48)
Total focal species 1.58 (1.50–1.66)
3.15 (2.99–3.30)
1.65 (1.58–1.73)
0.92 (0.87–0.96)
1.07 (1.03–1.12)
1.38 (1.26–1.49)
Annual Adjusted Focal Species Fatality Rates (Fatalities per Megawatt and 95% CI) Based on Modified Smallwood (2007) Detection Probabilities, BYs 2005–2010
SpeciesBird Year and Rate (95% CI)
2005 2006 2007 2008 2009 2010American kestrel 0.57
(0.50–0.71)0.90 (0.78–1.01)
0.92 (0.80–1.05)
0.57 (0.51–0.63)
0.56 (0.50–0.62)
0.69 (0.55–0.84)
Burrowing owl 0.90 (0.75–1.05)
2.43 (2.16–2.70)
0.88 (0.79–0.98)
0.36 (0.31–0.41)
0.70 (0.62–0.78)
0.62 (0.49–0.75)
Golden eagle 0.07 (0.07–0.08)
0.16 (0.15–0.17)
0.07 (0.07–0.08)
0.05 (0.05–0.05)
0.05 (0.05–0.06)
0.07 (0.05–0.08)
Red-tailed hawk 0.39 (0.37–0.41)
0.54 (0.51–0.58)
0.28 (0.26–0.29)
0.15 (0.14–0.16)
0.13 (0.12–0.13)
0.32 (0.29–0.34)
Total focal species 1.93 (1.77–2.14)
4.03 (3.73–4.32)
2.16 (2.00–2.32)
1.13 (1.05–1.21)
1.44 (1.35–1.54)
1.70 (1.50–1.89)
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APWRA-WIDE ESTIMATES OF TOTAL FATALITIES
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APWRA-Wide Estimates of Total Annual Fatalities (±95% CI) Based on QAQC and Modified Smallwood (2007) Detection Probabilities―Focal Species, BYs 2005–2010
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Bird Use and Total APWRA-Wide Fatalities (±95% CI) Based on QAQC Detection Probabilities, BYs 2005–2010
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Three-year Rolling Averages of Estimated Annual Total Fatalities (±95% CI) Based on QAQC and Modified Smallwood (2007) Detection Probabilities, BYs 2005–2010
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Annual Estimated Total APWRA-Wide Focal Species Fatalities (95% CI) Based on QAQC Detection Probabilities, BYs 2005–2010
SpeciesBird Year and Fatalities (95% CI)
2005 2006 2007 2008 2009 2010American kestrel 207
(182–231)344 (308–380)
347 (316–379)
213 (196–230)
203 (186–220)
205 (173–273)
Burrowing owl 237 (214–260)
837 (762–912)
285 (260–310)
138 (122–154)
216 (196–237)
190 (162–218)
Golden eagle 64 (60–67)
99 (94–105)
43 (41–44)
29 (28–29)
43 (41–45)
38 (33–43)
Red-tailed hawk 339 (322–357)
429 (405–452)
202 (195–210)
103 (99–108)
94 (89–100)
206 (191–220)
Total focal species 846 (778–914)
1,709 (1,568–1,849)
877 (811–943)
483 (445–521)
556 (511–601)
638 (559–718)
Annual Estimated Total APWRA-Wide Focal Species Fatalities (95% CI) Based on Modified Smallwood (2007) Detection Probabilities, BYs 2005–2010
SpeciesBird Year and Fatalities (95% CI)
2005 2006 2007 2008 2009 2010American kestrel 335
(282–388)461 (400–522)
465 (410–519)
263 (237–288)
270 (241–298)
271 (223–320)
Burrowing owl 369 (321–416)
1,131 (1,013–1,248)
385 (345–425)
171 (150–193)
289 (257–321)
254 (213–294)
Golden eagle 57 (53–61)
88 (81–94)
39 (36–41)
26 (24–29)
39 (36–43)
34 (29–39)
Red-tailed hawk 207 (198–216)
275 (259–291)
132 (126–138)
72 (67–76)
64 (60–69)
133 (123–144)
Total focal species 968 (896–1,039)
1,954 (1,820–2,088)
1020 (952–1,088)
532 (499–566)
662 (619–706)
693 (628–757)
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Various Measures of the Reduction in Total Annual Fatalities of the Four Focal Species in the APWRA over Time Based on QAQC Detection Probabilities
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SEASONAL SHUTDOWN
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Winter Fatality Detections (%) for the Four Focal Species at on-Diablo Winds Operating Group Turbines in the APWRA, Bird Years 2005-2010.
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Percentage of Annual Fatalities in Winter at Non–Diablo Winds Turbines—Focal Species, BYs 2005–2010
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Percentage of BUOW and AMKE Fatalities Composed of Feather Spots and Documented in Winter and Non-Winter Periods, BYs 2005–2010
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REPOWERING
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Average Annual Adjusted Focal Species Fatality Rates (Fatalities Per Megawatt and 95% CI) in the APWRA for the Repowered Buena Vista and Diablo Winds Turbines and All Other Monitored Turbine Strings.
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EFFECTS OF BLEED THROUGH ON ESTIMATES OF TOTAL FATALITIES
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PERCENT BIAS AS A FUNCTION OF SEARCH INTERVAL LENGTH
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Annual Estimated Total APWRA-Wide Focal Species Fatalities Based on QAQC Detection Probabilities, BYs 2005–2010
SpeciesBird Year and Fatalities
2005 2006 2007 2008 2009 2010
American kestrel 207 344 347 213 203 205
Burrowing owl 237 837 285 138 216 190
Golden eagle 64 99 43 29 43 38
Red-tailed hawk 339 429 202 103 94 206
Total focal species 847 1,709 877 483 556 639
Annual Estimated Total APWRA-Wide Focal Species Fatalities Based on QAQC Detection Probabilities, Re-Adjusted to Account for Bleed-Through, BYs 2005–2010
SpeciesBird Year and Fatalities
2005 2006 2007 2008 2009 2010
American kestrel 189 297 299 176 173 176
Burrowing owl 218 720 245 114 184 163
Golden eagle 60 88 38 25 38 34
Red-tailed hawk 325 406 191 97 89 195
Total focal species 792 1,512 773 412 485 567
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2005 2006 2007 2008 2009 20100
100
200
300
400
American Kestrel
StandardAdjusted
Bird YearEstim
ated
APW
RA-W
ide
Fata
l-iti
es
2005 2006 2007 2008 2009 20100
200
400
600
800
1000
Burrowing Owl
StandardAdjusted
Bird YearEstim
ated
APW
RA-W
ide
Fata
l-iti
es
2005 2006 2007 2008 2009 20100
100
200
300
400
500
Red-tailed Hawk
StandardAdjusted
Bird YearEstim
ated
APW
RA-W
ide
Fata
l-iti
es
2005 2006 2007 2008 2009 20100
20406080
100120
Golden Eagle
StandardAdjusted
Bird YearEstim
ated
APW
RA-W
ide
Fata
l-iti
es
SLIDE TITLE
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Conclusions There is strong evidence of a reduction in raptor fatalities in the
APWRA since 2005, concomitant with the general decline in installed capacity, the removal of hazardous turbines, an increase in the duration and intensity of the seasonal shutdown, and the repowering of portions of the APWRA. Some metrics indicate that the 50% reduction in focal species fatalities has been achieved.
There is substantial evidence to support the hypothesis that the winter shutdown has resulted in a decrease in large raptor fatalities, particularly for red-tailed hawk and golden eagle. There also appears to be a beneficial effect for American kestrel. Burrowing owl fatalities do not appear to be directly related to the winter shutdown, and several lines of evidence indicate that these results are confounded by predation-related fatalities.
There is evidence that repowering the APWRA with larger modern turbines would result in a significant reduction in the number of raptors killed per megawatt of power produced.
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Q&A
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