Abstract
In 2008, Jacques Whitford Limited (Jacques Whitford) was retained by Suncor Energy Products Inc. (Suncor) and Acciona Wind Energy Canada (Acciona) to undertake a bird and bat post-construction monitoring program (the Program) for the Ripley Wind Power Project (the Project) near the Town of Ripley in Bruce County, Ontario. The Project began commercial operation on January 21, 2008. The purpose of the Program was to characterize the effect of the Project on the breeding bird community of the site and to collect data on the mortality rates of birds and bats that use or fly through the site during spring and fall migration.
The Program was developed in cooperation with Environment Canada and the Ministry of Natural Resources (MNR) as part of the Environmental Assessment of the Project. The Program consisted of avian monitoring and mortality surveys, both of which occurred in Spring and Fall 2008. Mortality surveys or carcass searches were conducted in conjunction with searcher efficiency trials and scavenger impact trials, while avian monitoring consisted of breeding bird surveys and fall diurnal migration surveys.
Two searchers conducted bird and bat mortality surveys at the Ripley Wind Farm from mid-April through May, and July through mid-October. Carcass searches followed a grid-pattern measuring 80 m by 80 m, and were centered around the base of each turbine. Each grid included between 13 and 20 parallel transects, each of which was visually ground-scanned for bat and bird carcasses. Meteorological conditions and search dates and times were recorded for each turbine searched. In addition, photos were taken and unique identification codes were assigned when carcasses were encountered.
Searcher efficiency trials and scavenger impact trials were carried out during mortality surveys searches. Searcher efficiency trials were carried out two to three times a week, the results of which were used to estimate the number of bird and bat mortalities and correct for detection bias. For these trials, one searcher placed two to three marked carcasses (i.e., control) at various turbines. An alternate searcher would continue scheduled searches, without the knowledge of where the control carcasses were located.
Scavenger impact trials were carried out in order to determine the rate at which bat and bird carcasses were removed by local scavenging wildlife. These trials ran once in the spring, and once monthly for the fall season (two weeks per trial). Two carcasses were placed at each turbine and checked for evidence of scavenging or removal over the following two week period, concurrent with carcass searches. A scavenger impact trial form was completed in order to record weather data the day of carcass placement and level of scavenging or removal during each subsequent daily survey.
Avian monitoring surveys included breeding bird surveys and fall diurnal migration surveys. Breeding bird surveys were conducted twice in June of 2008. As recommended by Environment Canada, roadside point count stations and cultural meadow stations were identical to those used during the 2004 pre-construction monitoring program, thus allowing for direct comparison of the results between the two years. The use of each area by breeding birds, and any sensitive species observed (i.e., colonial waterbirds and species of conservation concern) were determined during 10 minute station surveys.
Environment Canada deemed spring and fall dawn migration surveys unnecessary. Thus, the diurnal migration monitoring carried out for post-construction in 2008 do not reflect the methodology employed pre-construction in 2004. Fall diurnal migration monitoring was carried out from September through mid-November. Two field ornithologists were posted to the east and west sides of the Project, simultaneously carrying out the surveys once a week from 9 a.m. to 12 p.m. over the course of ten weeks. Species and abundance of migrating diurnal birds observed in the area were documented. B
ird and bat mortalities appeared to be quite low during the spring monitoring period. The corrected mortality estimates for spring were 0.25 birds per turbine and 0.17 bats per turbine, with no bat carcasses located during the 2.5-week monitoring period in April. The fall monitoring period brought higher mortality rates, with 2.76 birds per turbine and 12.83 bats per turbine. The highest mortality rates occurred in the fall for birds (October) and in late summer for bats (August). The Ripley Wind Farm yielded corrected mortality estimates of 3.01 birds per turbine per monitoring period, and 1.5 birds per MW per monitoring period; as well as 13.00 bats per turbine per monitoring period, and 6.49 bats per MW per monitoring period. Bat fatalities have been reported to range from 0.1 bats per turbine per year to 69.7 bats per turbine per year (Arnett et al, 2008), and bird fatalities ranging from 0.63 birds per turbine per year to 7.7 birds per turbine per year (NWCC, 2004). All of the bats found during the mortality surveys are species typical of Ontario, and typical of Bruce County. None of the species found are considered species of conservation concern.
Of those turbines exhibiting higher numbers of fatalities during the entirety of the monitoring program (turbines #10 having 9 fatalities, and turbines #5, # 29 and #38 each eight fatalities, and turbine #3 having seven fatalities), only turbine #29 is located relatively close (within 300 m) to a woodlot measuring 10 ha or larger. It can be concluded that though some turbines were sited close to woodlots, especially large woodlots, they were not situated close enough to critically impact the species of birds or bats using this habitat.
The species recorded during avian monitoring in 2008 are typical of southern Ontario agricultural environments. A total of 97 species were observed during both the breeding bird and fall diurnal migration surveys. During the breeding bird surveys; 62 species were observed, with the most frequently encountered being (in descending order of frequency) Red-winged Blackbird, American Robin, Savannah Sparrow, and Song Sparrow. During the fall diurnal migration surveys, 58 species were observed; a total of 965 separate observations were made resulting in approximately 27 individuals being recorded. The majority of the birds (67% of observations and 65% of all individuals) were observed flying within 40 m of the ground (i.e., below the rotor swept area). Approximately 27% of 8% of avian individuals were observed flying well above tree height and higher, respectively, which places them within the sphere of the turbine blades. Overall, a notably smaller proportion of birds were observed flying at a height that puts them below risk of collision with the turbine blades, as compared to those flying below this risk-height.
Although no large concerns were identified during the pre-construction monitoring work at the Ripley Wind Farm, some discussion should be raised regarding the larger than expected quantities of birds observed during the fall avian monitoring program. With regards to the mortality monitoring program, the number of carcasses located, and the number of estimated mortalities computed, fall within the higher end of the expected range of mortalities as compared to numerous other wind farm studies throughout North America.