Annual Report for the Maple Ridge Wind Power Project Post-Construction Bird and Bat Fatality Study - 2008


Title: Annual Report for the Maple Ridge Wind Power Project Post-Construction Bird and Bat Fatality Study - 2008
Publication Date:
May 14, 2009
Pages: 80
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Jain, A.; Kerlinger, P.; Curry, R.; Slobodnik, L.; Lehman, M. (2009). Annual Report for the Maple Ridge Wind Power Project Post-Construction Bird and Bat Fatality Study - 2008. Report by Curry & Kerlinger LLC. pp 80.

The Maple Ridge Wind Power Project consists of 195 wind turbines and three permanent meteorology towers on the Tug Hill Plateau of Lewis County, just west of Lowville, New York. In 2005, a total of 120 Vestas wind turbines were constructed within the Phase I project area; the remaining 75 turbines in Phase IA and II of the project were constructed in May to December 2006. Each 1.65 MW turbine consists of an 80m (262 feet) tall tubular steel tower; a maximum 82m (269 feet) diameter rotor; and a nacelle which houses the generator, transformer and power train. The towers have a base diameter of approximately 4.5m (15 feet) and a top diameter of 2.5m (8 feet). The tower is topped by the nacelle, which is approximately 2.8m (9 feet) high and 7.6m (25 feet) long, and connects with the rotor hub. The rotor consists of three 41m (134 feet) long composite blades. Nearly one-third (57 out of 195; 29.2%) of the nacelles are equipped with L-864 FAA aviation obstruction beacons (lights) consisting of flashing red strobes (for night) and no illumination during the day. With a rotor blade oriented in the 12 o'clock position, each turbine has a maximum height of approximately 122 m (400 feet). All components of the turbine are painted white.


The current report reflects data collected between April 15 and November 9, 2008, and follows two annual reports covering the periods: summer-fall 2006 and April 30- November 14, 2007. As such, the current report is the second complete 3-season of study (Spring-Summer-Fall, winter studies precluded by heavy snowfall and limited site accessibility). Weekly carcass searches were conducted at 64 of 195 (32.8%) turbine sites. We completed 1,882 individual turbine searches, equivalent to about 30 rounds of searches at the 64 turbines.


Two out of the three meteorological towers were also searched weekly for a total of 60 searches, from April 15, 2008 to November 5, 2008 (30 rounds). A total of 74 avian incidents were recorded by searchers during standardized surveys under wind turbines, representing 53 incidents identified to 32 species, 6 incidents that were attributable to family but not species, and 15 incidents that could not be identified to a taxonomic group because they were partially scavenged or decayed prior to being found. Of the 53 identified incidents, there were 22 songbird species, 3 game bird species (Ruffed Grouse, American Woodcock and Wild Turkey), 3 raptor species (American Kestrel, Cooper's Hawk and Sharp-shinned Hawk), 2 water bird/shorebird species (Mallard and Killdeer) and two 'songbird-like' species (Belted Kingfisher, Mourning Dove). Thirty-nine out of the 74 (52.70%) incidents identified to species were night migrants or belonged to species that showed some evidence of night migration. Of all 42 identified songbirds, (excluding incidental finds), 32 (76.19 %) were night migrants. While these birds are classified as 'night migrants' we are not certain that all were migrating at the time of collision. The greatest number of bird incidents occurred during October, but numbers of fatalities did not vary greatly between months.


A total of 23 avian incidents were recorded by searchers or reported by WRA employees at times or locations other than during standardized weekly surveys. These incidental bird carcass finds consisted of 1 raptor species (one Sharp-shinned Hawk), 9 songbird species (one each of Black-capped Chickadee, Eastern Kingbird, European Starling, Grey Catbird, Pine Warbler, Red-eyed Vireo, Rose-breasted Grosbeak, and Yellow-rumped Warbler, as well as two Bobolinks. Two additional songbirds were identified only as a kinglet sp. and a passerine sp. In addition, we found a woodpecker species (one Yellow- bellied Sapsucker), two waterbird/shorebird species (three Killdeer, one Gull spp.) and five unidentified bird incidents.


The term "incident" is used here to refer to either a fatality or injury of a bird or bat found within the wind project area and does not necessarily indicate that the cause of death or injury was wind turbine related. This term is not to be confused with the term defined earlier, "incidental find", which refers to incidents found at times other than during standardized surveys and at sites outside the 64 turbines searched.


Remains of 140 bats were found by searchers during standardized surveys (April 15, 2008 to November 9, 2008), representing five species (61 Hoary Bats, 29 Silver-haired Bats, 16 Eastern Red Bats, 24 Little Brown Bats and 7 Big Brown Bats, along with two identified only as myotis spp. and one unknown species). The greatest number of bat incidents occurred during the fall dispersal and migration period, with 114 (81.4%) bat carcasses found between July 1, 2008 and September 30, 2008. A total of 76 bat incidents were recorded by searchers or reported by WRA employees at times or locations other than during standardized surveys on weekly searched sites. Of these fatalities, 32 were Hoary Bats, 5 were Eastern Red Bats, 17 were Silver-haired Bats, 11 were Little Brown Bats, 8 were Big Brown Bats, and 3 were unidentified species.


Bat carcasses were found closer to turbine tower bases than bird carcasses (bats -25.9m + 2.70 95% CI; birds -39.01m + 4.29 95% CI). Unlike in 2007, there was no evidence that bat fatalities were different at turbines close to wetland areas vs. turbines located farther from wetlands. There was also no evidence that bat or bird fatalities were different between wooded vs. non-wooded turbine sites. Fatality rates of night migrant birds and bats were not statistically different between lit (FAA L-864 obstruction lights) and unlit turbines, as was found in 2006 and 2007. Neither bird nor bat fatality rates were significantly greater at the northwest-edge of the Wind Resource Area (hypothesized as the source of initial contact of bats with the Wind Resource Area during the fall).


The amount of area searchable under each tower and the numbers of towers searched per round were adjusted when calculating final fatality estimates. In addition, carcass removal (scavenging) and searcher efficiency studies were conducted to estimate the proportion of carcasses missed by the searchers and the proportion removed by scavengers within the 7-day search cycles. These rates, along with the proportion of towers searched and the average number of towers searched per survey round were used to estimate the total number of fatalities likely to have occurred during the study period at all 195 turbines at the Maple Ridge Wind Resource Area (WRA).


The project was scheduled to start on April 15, 2008 (Late season snowfall in March, precludes clearing and searching of turbine areas prior to early-April). In the first week of searching (April 15-21, 2008), 58 out of the total of 64 turbine sites (~91%) were "set up" and searches immediately began on those towers. Four more turbine sites were added by April 23, 2008 (these were earlier inaccessible due to snow) and the last two sites were established and being searched by May 10, 2008 (these two were replacements for sites for which landowner permission had been withdrawn). Also, search areas under meteorological towers 1 and 2 were established and searches began on April 15 and 16, 2008, respectively.


By dividing the estimated number of incidents by the number of turbines and by 1.65 MW per turbine searched in each period, a rate of incidents/turbine and incidents/Megawatt was calculated for the study duration. In addition, by dividing the number of incidents/turbine by the rotor swept area (m2) and multiplying that figure by 2000, we are able to calculate the number of incidents/2000m2 rotor swept area. A typical 1.65 MW wind turbine tower in New York State will produce approximately 4,400 MWh per year (William Moore, PPM-Atlantic Renewable, pers. comm.). The metric "incidents/MWh produced" is calculated for the duration of the project period.


It is presumed that some of the carcasses noticed during non-survey activities (site maintenance and scavenger checks, etc.) could have been discovered during regular surveys. Contrary to standard practice, since a number of incidental findings occurred during these non-survey activities, we did an additional calculation of mortality rates using incidental finds that met the criteria mentioned above. The actual estimate of mortality is likely between these two estimates. See Results for 95% CI.


The estimates for birds are:


  • 7-Day standardized surveys (Total period 208 days): 667 incidents/period, 2.07 incidents/Mw/period, 3.42 incidents/turbine/period, 0.0014 incidents/MWh produced and 1.30 incidents per 2000m2 rotor swept area/period.
  • 7-Day standardized surveys + added incidentals (Total period 208 days): 733 incidents/period, 2.28 incidents/Mw/period, 3.76 incidents/turbine/period, 0.0015 incidents/MWh produced and 1.42 incidents per 2000m2 rotor swept area/period.
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