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3 Ecological Effects of Wind-Energy Development
Pages 67-139

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From page 67...
... Although other sources of development on sites that are suitable for wind-energy development affect wildlife and their habitats (e.g., mineral extraction, cutting of timber) , and there are other sources of anthropogenic mortality to animals, as stated previously, this committee was charged to focus on wind energy, and therefore did not conduct a comprehensive comparative analysis of impacts from other sources of development.
From page 68...
... , the recent bat fatalities from wind turbines appear to be unprecedentedly high. More data on direct comparisons of turbine types are needed to establish whether and why migratory bats appear to be at the greatest risk of being killed.
From page 69...
... As discussed below, little is known about the circumstances contributing to fatalities, but issues such as turbine height and design, rotor velocity, number and dispersion of turbines, location of the turbine on the landscape, and the abundance, migration, and behavioral characteristics of each species present are likely to influence fatality rates. In addition, non-flying organisms may be affected by turbine construction and operation, because of alteration of habitat and behavioral avoidance, possibly due to noise, vibration, motion of turbines, or their mere presence in the landscape.
From page 70...
... Increased research using rigorous scientific methods will be critical to filling existing information gaps and improving reliability of predictions. In this chapter, we review the literature on the ecological effects of wind-energy development, focusing on wildlife and their habitats.
From page 71...
... Collisions with buildings kill 97 to 976 million birds annually; collisions with high-tension lines kill at least 130 million birds, perhaps more than 1 billion; collisions with communications towers kill between 4 and 5 million based on "conservative estimates," but could be as high as 50 million; cars may kill 80 million birds per year; and collisions with wind turbines killed an estimated 20,000 to 37,000 birds per year in
From page 72...
... In addition, it is necessary to consider the possible cumulative bird deaths that can be expected if the use of wind energy increases according to recent projections (see Chapter 2)
From page 73...
... The scarcity of reported fatalities also may be due in part to the rarity of post-construction studies designed specifically to detect bat fatalities at wind-energy facilities. Recent surveys indicate that some wind-energy facilities have killed large numbers of bats in the United States (Arnett 2005; Johnson 2005)
From page 74...
... . The greatest difference between fatalities at wind-energy facilities in the eastern United States and those in other regions is the relative abundance of doves,
From page 75...
... Total annual bird fatalities per turbine and per MW are similar for all regions examined in these studies, although data from the two sites evaluated in the eastern United States suggest that more birds may be killed at windenergy facilities on forested ridge tops than in other regions. It is not known whether this is due to higher risk of collisions at these sites, or higher abundance of birds in the region.
From page 76...
... In addition, lack of replication of studies among facilities and years makes it impossible to evaluate natural variability and the likelihood of unusual episodic events in relation to bird fatalities. Influences of Turbine Design on Bird Fatalities The structure and design of existing wind turbines vary considerably, and it is likely that additional modifications will occur over time.
From page 77...
... . Much of the early work on fatalities at wind-energy facilities occurred in California, because most wind energy was produced at three windresource areas: APWRA, San Gorgonio, and Tehachapi.
From page 78...
... Wind Project Turbines of MW (m) MW Pacific Northwest Stateline, OR/WAb 454 300 47 1735 0.66 Vansycle, ORb 38 25 47 1735 0.66 Combine Hills, ORb 41 41 61 2961 1.00 Klondike, ORb 16 24 65 3318 1.50 Nine Canyon, WAb 37 48 62 3019 1.30 Totals or simple averages 586 438 56 2554 1.02 Weighted averages 586 438 49 1945 0.808 Rocky Mountain Foote Creek Rim, WY Phase Ic 72 43 42 1385 0.60 Foote Creek Rim, WY Phase IIc 33 25 44 1521 0.75 Totals or simple averages 105 68 43 1453 0.675 Totals or weighted averages 105 68 43 1428 0.655 Upper Midwest Wisconsin 31 20 47 1735 0.66 Buffalo Ridge Phase Id 73 22 33 855 0.30 Buffalo Ridge Phase Id 143 107 48 1810 0.75 Buffalo Ridge, MN Phase IId 139 104 48 1810 0.75 Top of Iowad 89 80 52 2124 0.90 Totals or simple averages 475 333.96 46 1667 0.67 Totals or weighted averages 475 333.96 46 1717 0.53 East Buffalo Mountain, TNe 3 2 47 1735 0.66 Mountaineer, WVe 44 66 72 4072 1.50 Totals or simple averages 47 68 60 2903 1.08 Overall (weighted average)
From page 79...
...  ECOLOGICAL EFFECTS OF WIND-ENERGY DEVELOPMENT Raptor Mortality All Bird Mortality Number Number Number Number per Turbine per MW per Turbine per MW per Year per Year per Year per Year Source 0.06 0.09 1.93 2.92 Erickson et al.
From page 80...
... 80 ENVIRONMENTAL IMPACTS OF WIND-ENERGY PROJECTS FIGURE 3-1 Composition of bird fatalities at 14 wind-energy facilities in the 3.01 United States. SOURCES: Compiled by committee from Erickson et have been redrawn.
From page 81...
... ; and Tehachapi Pass has approximately 3,700 turbines with an installed capacity of approximately 600 MW (~162 kW/turbine)
From page 82...
... studies are the most comprehensive to date, due to small sample sizes for turbines greater than 150 kW, extrapolation of fatality rates to all turbines in the AWPRA may not be appropriate.
From page 83...
... 83 ECOLOGICAL EFFECTS OF WIND-ENERGY DEVELOPMENT FIGURE 3-3 Mountaineer Wind Energy Center, West Virginia. The five turbines in this photograph are at the southwest end of the array of 1.5 MW turbines; they are at the lower left of the aerial view in Figure 3-7.
From page 84...
... Nonetheless, the potential cumulative impacts of these turbines should not be overlooked, especially for resident species. The estimated fatality rates for raptors at the older California turbines (e.g., Orloff and Flannery 1992; Anderson et al.
From page 85...
... . Most bird fatalities at wind-energy facilities are assumed to be caused by collisions with wind turbine blades.
From page 86...
... 2005; Gauthreaux and Belser 2006) , there is no evidence to suggest a lighting effect on passerine fatalities at wind-energy facilities, with the exception of the Mountaineer Wind Energy Center in West Virginia.
From page 87...
... A continent-wide study of nocturnal bird migration based on birds crossing the disc of the moon during four nights in October in 1952 (Lowery and Newman 1966) found little or no evidence that migrating birds were influenced by major rivers or mountain ranges in the eastern United States.
From page 88...
... The unadjusted per-turbine and per-MW raptor fatality rates reported for these sites are 0.006 and 0.03 for San Gorgonio, 0.04 and 0.20 for Tehachapi, and 0.1 and 1-1.23 for the APWRA. The primary difference among the three sites appears to be the abundance of raptors (Erickson et al.
From page 89...
... Recent marine radar studies conducted with modern X-band equipment capable of estimating target altitude from ~10 m to 1.5 km agl suggest that most nocturnal migrants fly above 125 m agl, the upper reach of most modern wind turbines. For example, using X-band marine radar in a vertical configuration, Mabee and Cooper (2002)
From page 90...
... Nevertheless, prey abundance may also strongly influence raptor abundance and thus risk of collisions. Temporal Pattern of Bird Fatalities at Wind-Energy Facilities Although additional research is needed for more complete understanding of temporal patterns of fatalities at wind-energy facilities, a number of patterns emerge and it is clear that risk of fatality differs with location, meteorological condition, time of night, and time of year for both birds and bats.
From page 91...
... Bat fatalities at wind-energy facilities in the eastern United States are much higher than those in western states. Of the 45 bat species known from North America (north of Mexico)
From page 92...
... of installed capacity. cOverall estimated percent searcher efficiency using bat or bird (*
From page 93...
... jWeighted mean number of bat fatalities/MW with weights equal to the proportion of 0.66 MW (n=3 of 18)
From page 94...
... has been reported in California, but is not included in this table. bPacific Northwest data from one wind-energy facility in California, three in eastern Oregon, and one in Washington; Rocky Mountain data from one facility each in Wyoming and Colorado; Upper Midwest data from one facility each in Minnesota, Wisconsin, and Iowa; South-Central data from one facility in Oklahoma; East data from one facility each in Pennsylvania, West Virginia, and Tennessee.
From page 95...
... . High fatality rates also can be expected for other species in the southwestern United States, where bat fatalities have not been monitored, and at wind-energy facilities in western states where rigorous monitoring for bat fatalities has been limited (Kunz et al.
From page 96...
... The lack of multiyear studies and previous, possibly biased estimates of fatalities at most existing wind-energy facilities makes it difficult to draw general conclusions about the long-term effects of bat deaths on bat populations. This is partly due to the lack of efforts to look for bats in early studies, since bat fatalities were not recognized as a problem.
From page 97...
... Most modern wind turbines are tall and white, extending well above the forest canopies in the eastern United States, and quite likely are visually (if not acoustically) detectable to bats on cloudless nights.
From page 98...
... , and if bats respond to high densities of flying insects near wind turbines, their chances of being struck by turbine blades probably are increased (Kunz et al.
From page 99...
... Can migratory species sustain high fatality rates, insofar as eastern red bats already appear to be in decline in New York (Mearns 1898) and in three Midwestern states (Whitaker et al.
From page 100...
... Temporal Patterns of Bat Fatalities at Wind-Energy Facilities Much of the uncertainty about spatial and temporal factors responsible for high fatalities, especially those experienced by migratory tree-roosting species, reflects the scarcity of intensive and long-term studies conducted on these species, especially at wind-energy facilities during the maternity
From page 101...
... However, higher bat fatalities are not confined to forested mountain ridges such as the mid-Atlantic region and elsewhere in the eastern United States. If this is the case, migratory bats could be vulnerable to high mortality from expanded wind-energy development in other regions of North America.
From page 102...
... 102 ENVIRONMENTAL IMPACTS OF WIND-ENERGY PROJECTS FIGURE 3-6 Migration route of an Indiana bat over forested ridge tops in eastern Pennsylvania (immediately south of Wilkes Barre, Luzerne County)
From page 103...
... An aerial photograph (Figure 3-7) provides an example of this variation on the Mountaineer Wind Energy Center in Tucker County, West Virginia.
From page 104...
... (2005) estimated that disturbance resulting from the construction of eight of the turbines at the Mountaineer Wind Energy Center ranged from 3.9 to 7.1 acres per turbine, not including forest removal for road construction and associated maintenance facilities.
From page 105...
... Forested landscapes in the eastern United States are fragmented over broad geographic regions and species associated with edges generally have not experienced declines (e.g., Bell and Whitmore 1997)
From page 106...
... Because vehicular traffic on wind-energy sites typically is infrequent, it is unlikely that collision with vehicles will be a significant source of mortality resulting from wind-energy development at most sites, including the Mid-Atlantic Highlands. • Forest roads may result in a modification of animal behavior.
From page 107...
... Influences of Habitat Alteration on Birds Effects of wind-energy development on habitats used by birds can be divided into two general categories: loss of habitat (including avoidance of disturbed and adjacent areas) , and fragmentation effects to remaining habitat.
From page 108...
... . Anecdotal evidence indicates that raptor use of the APWRA in California may have increased since installation of wind turbines (Orloff and Flannery 1992; AWEA 1995)
From page 109...
... However, the response of bird species to habitat alterations caused by changes in vegetation associated with timber management, mining, and insect outbreaks have been widely studied in the Mid-Atlantic Highlands (e.g., Duguay 1997; Bell and Whitmore 2000; Duguay et al. 2000, 2001; Hagan and Meehan 2002; Weakland and Wood 2005; Wood et al.
From page 110...
... . This rate of decline, however, needs to be re-evaluated because cerulean warblers extensively use ridge tops in some areas of the Mid Atlantic Highlands, and these areas are not sampled as much as midslopes or valley floors (Wood et al.
From page 111...
... All of these species are protected under the Migratory Bird Treaty Reform Act of 2005 and should be included in siting studies as well as in long-term monitoring of existing wind-energy facilities. Although habitat alteration resulting from wind-energy development often occurs at a relatively small scale, the cumulative effects of wind-energy development, in conjunction with changes in habitat from a variety of other past and present anthropogenic activities, could result in negative impacts on bird populations.
From page 112...
... Habitat alteration Habitat alteration does not Habitat alteration decreases use of area influence use of area within increases use of area within turbine sweep zone turbine sweep zone within turbine sweep zone Habitat alteration Dependent on decreases abundance magnitude of Negative impact Negative impact influences Positive impact No influence Negative impact Habitat alteration Positive impact Positive impact Dependent on increases abundance magnitude of influences FIGURE 3-8 The influence of habitat alteration associated with wind-energy facilities on bats is a function of the combined influences of the ways that habitat alteration influences abundance and risk of collision with turbine blades.
From page 113...
... . Clearing forests at and around wind-energy facilities could result in removal of actual or potential roost sites for Indiana bats, eastern red bats, hoary bats, and silver-haired bats, and several other species that occur in or migrate through the Mid-Atlantic Highlands.
From page 114...
... . Nonetheless, bat species that appear to be most at risk of being killed by wind turbines in the Mid-Atlantic Highlands include eastern red bats, hoary bats, silver-haired bats, and eastern pipistrelles.
From page 115...
... It is quite likely that construction of roads and clearings at wind-energy facilities in forested regions improves foraging habitats for several species of bats in the Mid-Atlantic Highlands, and elsewhere where similar habitat exists. All bat species known to occur in the eastern United States, including the Mid-Atlantic Highlands, are insectivorous.
From page 116...
... . Although habitat alteration resulting from wind-energy development often occurs at a relatively small scale, it is likely that the cumulative effects of wind-energy development, in conjunction with changes in habitat from a variety of other activities, will result in negative impacts on bat populations.
From page 117...
... For bats, the interaction among habitat alteration, influences on bat activity patterns, and risk of collision with wind turbines could be an important factor in bat fatalities in the Mid-Atlantic Highlands. Gaining increased understanding of these interactions could help inform in pre-siting risk assessments for bats.
From page 118...
... . Although not listed under the federal Endangered Species Act, this species is identified as endangered on state lists in New York, New Jersey, and Maryland; threatened in Pennsylvania; species of concern in North Carolina and Virginia; and a species "somewhat vulnerable to extirpation" in West Virginia.
From page 119...
... . Cyclically abundant in more northern habitats, this species reaches its southernmost distribution along the high ridges of Pennsylvania, Virginia, Maryland, and West Virginia (Brooks 1965)
From page 120...
... . Moreover, amphibians often are more sensitive to habitat alteration than birds and mammals (Marsh and Beckman 2004)
From page 121...
... Influences of Habitat Alteration on Fish and Other Aquatic Organisms Aquatic habitats are not common along Mid-Atlantic Highland ridges. By the very nature of the terrain, establishment of permanent bodies of
From page 122...
... Wind Energy Deployment System (WinDS) model and the PJM Interconnection queue (Table 3-5)
From page 123...
... cBased on assembled information for in-service wind projects and wind projects with state or local-level approval listed in the PJM interconnection queue (Boone 2006)
From page 124...
... , we estimate that the projected avian fatalities in the mid-Atlantic regions could range from a mean minimum of approximately 5,805 birds per year (based on the fatality rate at the Mountaineer Wind Energy Center, West Virginia) , to a maximum of approximately 25,183 birds per year (based on the fatality rate estimated for the Buffalo Mountain Wind Park in Tennessee)
From page 125...
... . dMaximum projected number of fatalities in 2020 is based on the product of 11.67 bird fatalities/MW reported from the Buffalo Mountain Wind Energy Center, TN (from Table 3-2)
From page 126...
... Based on currently available information on bat fatalities in the eastern United States, projected cumulative impacts using estimates of installed capacity for the Mid-Atlantic Highlands in the year 2020, along with supporting data, assumptions, and calculations, are in Table 3-7. Minimum and maximum estimates of installed capacity for this region range from 2,158
From page 127...
... . dMinimum projected number of fatalities in 2020 is based on the product of 15.3 bat fatalities/ MW/year reported from the Meyersdale Wind Energy Center, PA (from Table 3-4)
From page 128...
... Based on estimates of installed capacity and the limitations and assumptions regarding fatality rates noted above, the minimum and maximum projected fatalities of bats presented in Tables 3-4, 3-5, and 3-7 would range from 33,017 to 61,935 per year based on the NREL's WinDS model and 58,997 to 110,667 per year based on the PJM Interconnection queue. These projected cumulative impacts in 2020 based on the WinDS model and PJM Interconnection queue would cause annual fatalities of 9,542 to 31,983 hoary bats, 11,358 to 38,069 eastern red bats, 1,717 to 5,755 silver-haired bats, and 6,108 to 20,473 eastern pipistrelles in the midAtlantic region.
From page 129...
... scenarios, our projected fatality rates in the Mid-Atlantic Highlands bracket expected extremes. These projected fatalities can best be considered as hypotheses to be tested with future data on fatalities from the Mid-Atlantic Highlands and other regions where bird and bat fatalities have been reported, and by adjusting monitoring protocols to minimize potentially confounding assumptions (Kunz et al.
From page 130...
... To date, the highest fatality rates have been reported in the Mid-Atlantic Highlands, although recent evidence suggests that bats from grassland and agricultural landscapes may also experience high fatality rates. Migratory tree bats constitute over 78% of all fatalities reported at wind-energy facilities, and thus appear to be killed disproportionately to highly colonial species.
From page 131...
... It is essential that the potential for population effects be evaluated as wind-energy facilities become more numerous. • Fatality rates of migratory tree bats appear to be high in some landscapes (e.g., forested ridge tops)
From page 132...
... that are known to have narrow habitat requirements and whose niches are disproportionately altered. Information Needs Here we identify information needs related to understanding, predicting, and managing bird and bat fatalities and landscape and habitat alterations.
From page 133...
... on bird and bat fatalities.
From page 134...
... Hypothesis-Based Research on Bats Knowledge about bat fatalities at wind-energy plants is very limited, mainly because the large number of bats killed has been recognized only recently. Eleven hypotheses are listed below, as examples, to help address how, when, where, and why bats are being killed at wind-energy facilities (Kunz et al.
From page 135...
... . As bats respond to high densities of flying insects near wind turbines, they may be at increased risk of being struck by turbine blades.
From page 136...
... For example, while current evidence suggests that bat fatalities have been the highest at wind-energy facilities in forested mounted ridge tops in the Mid-Atlantic Highlands, recent monitoring studies in agricultural landscape in the Midwest and at wind-energy facilities in southwestern Alberta, Canada, suggest that fatality rates of migratory tree bats may be as high as those reported for the Mid-Atlantic Highlands. We also expect that high bat fatalities are occurring or will occur in the southwestern United States, where large numbers of Brazilian free-tailed bats form maternity colonies (McCracken 2003)
From page 137...
... that could avoid or reduce current fatality rates -- independent of a meta-analysis to assess biological significance and adverse cumulative impacts.
From page 138...
... Most wind-turbine-related bat fatalities in the United States have been of migratory species. To date, no fatalities of federally listed bat species have been documented, although as wind-energy development increases geographically, some threatened and endangered species could be at risk.
From page 139...
... , where some of the largest bat colonies in North America are known, may be at considerable risk from wind-energy development during both migratory and maternity periods. Projected development of wind-energy facilities throughout the United States should be evaluated for cumulative impacts on different species considered at risk.


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