Elsevier

Biological Conservation

Volume 168, December 2013, Pages 201-209
Biological Conservation

Review
Estimates of bird collision mortality at wind facilities in the contiguous United States

https://doi.org/10.1016/j.biocon.2013.10.007Get rights and content

Highlights

  • We estimate bird mortality at monopole wind turbines in the contiguous U.S.

  • Between 140,000 and 328,000 birds are killed annually at monopole turbines.

  • Mortality increases with increasing height of monopole turbines.

  • Mortality rates appear to be lower in the Great Plains relative to other regions.

Abstract

Wind energy has emerged as a promising alternative to fossil fuels, yet the impacts of wind facilities on wildlife remain unclear. Prior studies estimate between 10,000 and 573,000 fatal bird collisions with U.S. wind turbines annually; however, these studies do not differentiate between turbines with a monopole tower and those with a lattice tower, the former of which now comprise the vast majority of all U.S. wind turbines and the latter of which are largely being de-commissioned. We systematically derived an estimate of bird mortality for U.S. monopole turbines by applying inclusion criteria to compiled studies, identifying correlates of mortality, and utilizing a predictive model to estimate mortality along with uncertainty. Despite measures taken to increase analytical rigor, the studies we used may provide a non-random representation of all data; requiring industry reports to be made publicly available would improve understanding of wind energy impacts. Nonetheless, we estimate that between 140,000 and 328,000 (mean = 234,000) birds are killed annually by collisions with monopole turbines in the contiguous U.S. We found support for an increase in mortality with increasing turbine hub height and support for differing mortality rates among regions, with per turbine mortality lowest in the Great Plains. Evaluation of risks to birds is warranted prior to continuing a widespread shift to taller wind turbines. Regional patterns of collision risk, while not obviating the need for species-specific and local-scale assessments, may inform broad-scale decisions about wind facility siting.

Introduction

Wind energy has emerged globally as a promising alternative to fossil fuels. As of June 2013, more than 270 gigawatts (GW) of power generation capacity were installed across the world’s >13,000 wind facilities (The Wind Power, 2013). Roughly 20% of this capacity is installed in the United States (American Wind Energy Association, 2013), providing enough energy to power 18 million households. A continued increase of U.S. wind energy development is expected in response to the Department of Energy’s (DOE) goal to have 20% of total energy generated from wind power by 2030 (U.S. DOE, 2008). Conservationists have expressed concern about direct and indirect impacts of wind energy development on wildlife, including bird and bat collisions with wind turbines (Kunz et al., 2007a, Kunz et al., 2007b, Kuvlesky et al., 2007), habitat loss, and creation of barriers to wildlife movement (Drewitt and Langston, 2006, Kuvlesky et al., 2007, Pruett et al., 2009, Kiesecker et al., 2011). Despite the decommissioning of many lattice-tower turbines that have caused large numbers of bird collisions, such as those at Altamont Pass in California (California Energy Commission, 1989, Smallwood and Karas, 2009), bird collisions still occur at turbines with solid monopole towers (e.g. Johnson et al., 2002, Kerns and Kerlinger, 2004), which now comprise the vast majority of U.S. turbines.

Wildlife mortality from collisions with wind turbines is the most direct, visible, and well-documented impact of wind energy development. However, conclusions about collision rates and impacts of collisions on bird populations are tentative because most of the mortality data is in industry reports that are not subjected to scientific peer review or available to the public (Piorkowski et al., 2012). The accessible data—which could provide a non-representative sample of all studies—suggests that bird collision rates at turbines are lower than at other structures, such as communication towers, buildings, and power lines (Drewitt and Langston, 2006), and that mass collision events are rare at wind facilities (but see Johnson et al., 2002, Kerns and Kerlinger, 2004, American Bird Conservancy, 2011). Pre-construction assessment of collision risk at proposed wind facilities has been unreliable, with no clear link documented between predicted risk levels and post-construction mortality rates, likely due to substantial variation in collision rates among turbines and a failure to consider risks at individual proposed turbine sites (de Lucas et al., 2012a, de Lucas et al., 2012b, Ferrer et al., 2012). In addition, most risk assessments focus on the total numbers of birds predicted to be present at a site. A failure to consider species-specific risks may result in relatively high post-construction rates of mortality for some species even if total bird mortality is relatively low (Ferrer et al., 2012).

Mean estimates of annual U.S. mortality from wind turbine collisions range between 20,000 and 573,000 birds (Erickson et al., 2001, Erickson et al., 2005, Manville, 2009, Sovacool, 2012, Smallwood, 2013). Earlier estimates were generated by summarizing a small sub-set of industry reports and extrapolating mortality rates across all turbines (Erickson et al., 2001, Erickson et al., 2005), by using small samples of preliminary data (Sovacool, 2012), or by using undocumented methods (Manville, 2009). A recent study estimates annual U.S. collision mortality at 573,000 birds and greatly improves upon earlier efforts by using data from a large sample of wind facilities and by accounting for several methodological differences among the studies used (Smallwood, 2013). However, this study did not distinguish between lattice and monopole turbines. Because monopole turbines comprise the vast majority of all installed U.S. wind turbines, it is important to separately estimate mortality and assess correlates of mortality for this turbine type.

We reviewed the wind energy literature, including both peer-reviewed articles and unpublished industry reports, and extracted data to systematically estimate bird collision mortality and mortality correlates at monopole turbines in the contiguous U.S. Specifically, we (1) defined inclusion criteria to ensure a baseline level of rigor for studies used in the estimate, (2) fitted a predictive model that includes correlates of mortality, accounts for differences among studies in the proportion of the year during which collision events were sampled, and includes estimate uncertainty, and (3) implemented the fitted model to estimate bird collision mortality for wind facilities in the contiguous U.S.

Section snippets

Literature search

We searched Google Scholar, the Web of Science database (using the Web of Knowledge search engine), and the National Renewable Energy Laboratory’s Wind-Wildlife Impacts Literature Database (http://wild.nrel.gov/) to identify studies documenting bird collisions with wind turbines. We also searched Google because most industry reports are not indexed in databases. We used the search terms “bird AND wind turbine” with “collision,” “mortality,” “fatality,” “carcass,” and “post-construction”; all

Correlates of mortality

The additive 2-variable model that included turbine hub height and region was the most strongly supported model in our analysis, followed by the multiplicative height-region model. Because the relative strength of support was greater for the additive model (Table 1), we used this model for mortality prediction. The univariate region and hub height models each received less support than the 2-variable models; however, because both variables were included in the best-supported model, we compared

Comparison to other mortality estimates

Our mean projected estimate of 234,012 annual bird collisions in the contiguous U.S. – and even our low-end estimate (140,438) – is greater than most previous estimates, including ∼20,000 birds/yr (Sovacool, 2012), 10,000–40,000 birds/yr (Erickson et al., 2001, Manville, 2005), and 20,000–40,000 birds/yr (Erickson et al., 2005). Two recently published annual estimates exceed our upper estimate of 327,586 birds: 440,000 (Manville, 2009) and 573,000 (Smallwood, 2013). We provide the first

Role of the funding source

The funder had no role in study design; collection, analysis, and interpretation of data; in writing the report; and in the decision to submit the paper for publication.

Acknowledgments

We thank the following people and organizations for facilitating or providing access to unpublished studies: T. Bartunek, J.W. Demastes, K. Fuller, P. Kerlinger, K. Kronner, C. Machtans, D. Mason, T. Sandberg, G.D. Schnell, BHE Environmental, Curry and Kerlinger LLC., Iberdrola Renewables, and the National Renewable Energy Laboratory-National Wind Technology Center. We also thank T. Alison, J. Berry, M.M.P. Huso, D.H. Johnson, T. Longcore, A. Manville, M. Parr, and A.C. Peterson for discussions

References (56)

  • California Energy Commission (CEC), 1989. Avian mortality at large wind energy facilities in California: identification...
  • M. de Lucas et al.

    Using wind tunnels to predict mortality in wind facilities: the case of Griffon Vultures

    PLoS One

    (2012)
  • A.L. Drewitt et al.

    Assessing the impacts of wind facilities on birds

    Ibis

    (2006)
  • Ellison, L.E., 2012. Bats and wind energy – a literature synthesis and annotated bibliography. Open-file Report...
  • Erickson, W.P., Johnson, G.D., Strickland, M.D., Young Jr., D.P., Sernka, K.J., Good, R.E., 2001. Avian collisions with...
  • Erickson, W.P., Johnson, G.D., Young Jr., D.P., 2005. A summary and comparison of bird mortality from anthropogenic...
  • M. Ferrer et al.

    Weak relationship between risk assessment studies and recorded mortality in wind facilities

    J. Appl. Ecol.

    (2012)
  • Gritski, B., Downes, S., Kronner, K., 2010. Klondike III (phase 1) wind power project wildlife monitoring study....
  • M.M.P. Huso

    An estimator of wildlife fatality from observed carcasses

    Environmetrics

    (2010)
  • Johnson, G.D., Arnett, E.B., 2011. A bibliography of bat fatality, activity, and interactions with wind turbines....
  • G.D. Johnson et al.

    Collision mortality of local and migrant birds at a large-scale wind-power development on Buffalo Ridge, Minnesota

    Wildlife Soc. B.

    (2002)
  • Kerlinger, P., Curry, R., Culp, L., Fischer, B., Hasch, A., Wilkerson, C., 2007. Post-construction avian monitoring...
  • Kerns, J., Kerlinger, P., 2004. A study of bird and bat collision fatalities at the Mountaineer Wind Energy Center,...
  • J.M. Kiesecker et al.

    Win–win for wind and wildlife: a vision to facilitate sustainable development

    PlosONE

    (2011)
  • Klem Jr., D., 2009. Avian mortality at windows: the second largest human source of bird mortality on earth. In:...
  • F. Korner-Nievergelt et al.

    A new method to determine bird and bat fatality at wind energy turbines from carcass searches

    Wildlife Biol.

    (2011)
  • T.H. Kunz et al.

    Assessing impacts of wind-energy development on nocturnally active birds and bats: a guidance document

    J. Wildlife Manage.

    (2007)
  • T.H. Kunz et al.

    Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses

    Front. Ecol. Environ.

    (2007)
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