Abstract
EDP Renewables (EDPR) is operating the Headwaters Wind Farm (HWF) in Randolph County, Indiana. HWF became fully operational in 2014 and consists of 100 2.0-megawatt (MW) Vestas V110 wind turbines. This report details the post-construction fatality monitoring studies conducted in accordance with the HWF Habitat Conservation Plan (HCP) and Incidental Take Permit (ITP; TE85617C-0) for Indiana bats and northern long-eared bats.
The HCP identified 10 turbines with summer risk for Indiana bat and/or northern long-eared bat. After the receipt of the ITP and implementation of curtailment reduction, HWF feathered turbine blades at those turbines when wind speeds were below 5.0 meters per second (mps; 16.4 feet [ft] per second) during the summer maternity season (June 25 – July 31) to minimize impacts to summer maternity colonies. All turbines are within the migratory range of Indiana bat and northern-long eared bat. During the fall migration period (August 1 – October 15), HWF feathered turbine blades at all turbines when wind speeds were below 5.0 mps, on nights when temperatures were above 10° Celsius to minimize impacts to migrating Indiana and northern long-eared bats.
Post-construction monitoring was designed to meet a stand alone probability of detection, or g, of 0.25 during the fall migration season. Technicians searched 10 turbines with summer risk as road and pad areas to a distance of 100 m from the turbine, once a week, between July 2 to July 30. In the fall, a technician searched 60 turbines as road and pad plots to a distance of 100 m from the turbine. Dog-handler teams searched 35 turbines as cleared plots with a 70 m radius and five turbines as uncleared soy plots with a 70 m radius. All plots were searched once a week between August 5 to October 15, 2019. Searcher efficiency and carcass persistence trials were also conducted during both seasons to correct for detection and scavenger bias.
One Indiana bat was recorded at HWF on September 18, 2019. No northern long-eared bats were found at HWF. The most commonly found species were eastern red bat (50.7%), followed by silver-haired bat (23.1%) and hoary bat (8.9%). Species composition recorded at HWF was similar to previous studies at the Project and other wind facilities in Indiana. Five bats were found during the summer, and 401 bats were found in the fall. Two individuals each of two state-listed endangered species (little brown bat, and evening bat) were also recorded at HWF in the fall. No other state- or federally listed species were recorded. Thirty-seven bird carcasses were recorded; no state- or federally listed birds were found.
The overall bat fatality estimate was 11.74 bats per MW (90% Confidence Interval: 7.55–18.71). Five Indiana bats and one northern long-eared bat fatalities were estimated to have occurred during the monitoring period (M* at α = 0.5). These values fall below the permitted take for each species, meaning the project was in compliance with the ITP. Likewise, the probability that the annual take rate exceeded the thresholds for Indiana bat and northern long-eared bat did not exceed 95%, indicating that no adaptive management actions are necessary at this time.