Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses
This important peer-reviewed paper written by bat expert Dr. Thomas H. Kunz et al identifies the significant risk wind turbines pose for migratory and local bat populations in the mid-Atlantic Highlands region of the United States. The projected number of annual fatalities of bats at wind energy facilities in the Highlands in the year 2020 can reach up to 111,000 bats.
Projected cumulative fatalities
We have projected cumulative fatalities of bats at wind energy facilities for the Mid-Atlantic Highlands using data on current fatality rates (Table 1) and projections of installed capacity for wind energy facilities in the Highlands for the year 2020 (see WebTable 2 for supporting data, assumptions, and calculations). Projections of installed capacity range from 2158 MW (based on the National Renewable Energy Laboratory [NREL] WinDS model [nd]) to 3856 MW (based on the PJM electricity grid operator interconnection queue; see PJM ). Although the estimated number of bat fatalities reported for each study (WebTable 1) were not consistently corrected for search efficiency or for potential bias associated with carcass removal by scavengers, we have nonetheless used these estimates to project cumulative impacts on bats because they are the only fatality rates available for bats in this region.
In making our projections of cumulative fatalities, we have assumed that: (1) current variation in fatality rates is representative of the Mid-Atlantic Highlands,
(2) future changes in design or placement of turbines (eg more and larger installed turbines) will not cause deviations from current fatality estimates,
(3) abundance of affected bat species will not decrease due to turbinerelated fatalities or other factors (eg habitat loss), and
(4) projections of cumulative fatalities for other geographic regions differ from those in the Mid-Atlantic Highlands.
The projected number of annual fatalities in the year 2020 (rounded to the nearest 500) range from 33,000 to 62,000 individuals, based on the NREL's WinDS Model, and 59,000 to 111,000 bats based on the PJM grid operator interconnection queue. For the three migratory, treeroosting species from the Mid-Atlantic Highlands, the projected cumulative fatalities in the year 2020 based on the WinDS model and PJM grid operator queue, respectively, would include 9,500 to 32,000 hoary bats, 11,500 to 38,000 eastern red bats, and 1,500 to 6,000 silver-haired bats. Given the uncertainty in estimated installed wind turbine capacity for the Mid-Atlantic Highlands and existing data on bat fatalities reported for this region, the above projections of cumulative fatalities should be considered provisional and thus viewed as hypotheses to be tested as improved estimates (or enumerations) of installed capacity and additional data on bat life histories and fatalities become available for this region. Nonetheless, these provisional projections suggest substantial fatality rates in the future. At this time, we have avoided making projections of cumulative fatalities for the entire period from 2006-2020, because of uncertainty with respect to population sizes and the demographics of bat species being killed in this region.
If these and other species-specific projections are realized for the Mid-Atlantic Highlands, there may be a substantial impact on both migratory and local bat populations.