Abstract
Bitter Ridge Wind Farm, LLC (Bitter Ridge), is operating the Bitter Ridge Wind Farm (Project) in Jay County, Indiana. Bitter Ridge obtained an Incidental Take Permit (ITP; ESPER0014119) for the federally listed endangered Indiana bat and the federally listed threatened northern long-eared bat (hereafter, Covered Species) from the US Fish and Wildlife Service (USFWS) dated June 15, 2021. This report details the post-construction monitoring studies conducted in 2021, consistent with the Project’s Habitat Conservation Plan (HCP) and ITP for Covered Species, and the study plan developed for ITP monitoring in 2021. Post-construction monitoring was completed in accordance with the study plan. The initial draft of the study plan was submitted to the US Fish and Wildlife Service (USFWS) on April 16, 2021. The study plan was revised multiple times to account for changes in survey design and start dates (based on changes in anticipated ITP issuance schedule) and received final approval on August 26, 2021 (Marissa Reed, USFWS, pers. comm.). The study plan was designed to achieve a probability of detection, or g, of 0.25. As noted above, the ITP was received on June 15, 2021, and Bitter Ridge started operating under the HCP minimization regime the next day; ITP-level monitoring was mobilized as soon as possible after that and searches began on June 21. The overall goal of this post-construction monitoring study was to generate reliable fatality estimates for the Covered Species and to evaluate compliance with the incidental take authorization granted under the Project’s ITP. Specifically, the objectives of the study were to 1) estimate Covered Species take using the Evidence of Absence (EoA) framework as outlined in the HCP, and 2) determine overall bat fatality rates. This report presents the results of the study conducted within the Project from June 21 – October 15, 2021. Standardized carcass searches were completed for bats at three plot types: cleared plots, uncleared plots, and road and pad plots. During the summer study period (June 21 – July 31), 37 summer risk turbines were searched twice per week. A technician searched gravel road and pad plots at 15 turbines out to a distance of 100 meters (m; 328 feet [ft]) from the turbine. A dog handler team searched cleared plots at 14 turbines and uncleared plots (i.e., soy plots) at eight turbines. Both cleared and uncleared plots were searched at a 70-m (230-ft) radius. During the fall study period (August 1 – October 15), all 52 turbines were searched twice per week with a technician searching road and pad plots at 38 turbines and dog-handler teams searching cleared plots at 14 turbines. Searcher efficiency and carcass persistence trials were also conducted during each season to correct for detection and scavenger removal bias. The most commonly found bat species were eastern red bat (40.7%), silver-haired bat (28.0%), big brown bat (15.1%), and hoary bat (13.8%). Carcasses of three additional state-listed endangered species were recorded at Bitter Ridge including little brown bat (n = 1), evening bat (n = 1) and tri-colored bat (n = 1).Species composition recorded at the Project was similar to previous studies at the nearby Headwaters Wind Farm in Randolph County, Indiana. The overall probability of detection (g) distribution for 2021 post-construction monitoring surveys had a mean Bitter Ridge Post-construction Monitoring Studies WEST ii January 2022 of 0.33 (95% Confidence Interval [CI]: 0.32–0.35). During the study, 558 bat fatalities were found. The overall bat fatality rate was 15.02 bats per megawatt (90% CI: 11.07–20.91). Two Indiana bat carcasses were found at the Project, one at Turbine 37 on August 23, 2021, and one at Turbine 11 on October 11, 2021. No northern long-eared bat carcasses were found. Based on the first year of ITP monitoring, cumulative take to-date, M* at α = 0.5 (50th credible bound), is estimated to be 6 Indiana bats and 0 northern long-eared bats. Estimated take for the Covered Species falls below the permitted take level for both species, meaning the Project was in compliance with the ITP. The EoA model estimated the mean annual fatality rate at Bitter Ridge was 7.54 Indiana bats and 1.51 northern long-eared bats. The probability that the annual take rate exceeded the thresholds for either Covered Species did not exceed 95%, indicating that no adaptive management actions are necessary at this time.