Key Excerpts from the Executive Summary
This report, the fourth in a series, contains the results of the post-construction monitoring program for the period between July 1 and December 31, 2010. The Wind Plant achieved commercial operation on June 26, 2009, and all 86 WTGs had completed their commissioning works by June 29. With intermittent and periodic turbine shutdown to allow for ‘fine-tuning’ maintenance work, the first full week of operation of all 86 WTGs was the week of July 6, 2009.

Mortality monitoring was carried out by employees of Wolfe Island Wind Monitoring, an independent consulting firm, according to a schedule and methods prepared by Stantec that were based on the [Post-Construction] Follow-up Plan. In addition to carcass searches, trials to determine various corrective factors for searcher efficiency and scavenging rates were conducted during the Reporting Period.
A total of 54 carcasses of 22 bird species were collected during the Reporting Period.

Two raptor and vulture fatalities were recorded over the course of this Reporting Period: one Turkey Vulture and one Red-tailed Hawk. Correcting seasonally for searcher efficiency, scavenger and other removal rates, and the percent area searched, the 2 raptor/vulture and 52 other bird carcasses recovered represents an estimated total bird mortality for the Reporting Period of 8.27 birds/turbine (3.60 birds/MW). Bird mortality rates were much higher in the summer (July through September) than in the fall (October through December). The mortality rate for the six-month Reporting Period at the Wind Plant, at 3.60 birds per MW, is consistent with the results in nearby New York and other studies summarized by Arnett et al. (2007). The Reporting Period covered the entire period of concern, and so a comparison between sites is valid.

A total of 111 carcasses of four bat species were collected during the Reporting Period.

The Hoary Bat (54 fatalities), Eastern Red Bat (21 fatalities), and Silver-haired Bat (19 fatalities), are classified as long-distance migratory tree bats and comprised 84.7% of all bat fatalities. The majority of bat mortality occurred between the end of July and mid-September, peaking during late August. Correcting for searcher efficiency, scavenger and other removal rates, and percent area searched, the 111 recovered carcasses represent an estimated bat mortality for the Reporting Period of 21.84 bats/turbine (9.50 bats/MW).

The 2010 bat mortality rate at the Wind Plant, at 9.50 bats per MW, is at the low end of the range reported in North America and is considerably lower than the range reported in the eastern U.S. by Arnett et al. (2007). The bat mortality rate at the Wind Plant is consistent with the results in nearby New York and is roughly 25-40% lower than the mortality measured at Maple Ridge, New York (9.42-11.23 bats/MW; Jain et al., 2007). The Reporting Period covered the entire fall period of concern, and so a comparison between sites is valid.

In total, six species of waterfowl were observed foraging inland during the fall 2010 post-construction monitoring; all species were either geese or dabbling ducks. Species composition in 2010, dominated by Canada Geese, was very similar to that observed during the pre-construction monitoring in 2007 and post-construction monitoring in 2009. Overall, the total number of waterfowl days was higher during the 2009 and 2010 post-construction monitoring (311,774 and 236,583 respectively), compared to the 2007 pre-construction monitoring (117,838).

Generally, major waterfowl movement routes were similar in 2007, 2009 and 2010. All major routes were associated with the primary offshore staging areas, namely Reed’s Bay, Pyke’s Bay, Button Bay, Bayfield Bay and the small inlet off Carpenter’s Point Rd. Slight changes in routes between 2007, 2009 and 2010 were likely attributable to changes in foraging fields. Waterfowl did not appear to adjust their flight height in reaction to the WTGs, with the majority of ducks and geese flying at blade sweep height. In many cases, avoidance behavior was observed, as flocks of waterfowl adjusted their flight course as they approached a WTG.

Maximum numbers observed during any one winter raptor survey in 2010 for each species were 32 Short-eared Owls, 31 Rough-legged Hawks, 16 Northern Harriers, 15 Red-tailed Hawks and 4 American Kestrels. Only single observations of Bald Eagle, Copper’s Hawk and Merlin were made on any one survey.

Raptor numbers in 2010 were generally similar to those in 2006, and significantly higher than those observed in 2009. During the evening surveys, Short-eared Owl density was significantly higher than pre-construction surveys, with a greater than 100% increase in the number of observations. Trends observed through the 2006, 2009 and 2010 winter raptor monitoring generally correspond to results of the Kingston Christmas Bird Count in those years.

NOTE: The 2010 annual bat mortality rate is below the adaptive management threshold of 12.5 bats/MW, as identified in the approved Post-Construction Follow-Up Plan for the Wolfe Island Wind Plant. Although the bat mortality rate is below the threshold, TransAlta has proactively developed a research program that will take place between July 15 and September 30, 2011 during the fall bat migration period to evaluate practical measures to lessen the effects of operating wind turbines on bats at Wolfe Island. The bat mitigation research will involve operational control of selected turbines during night time hours and low wind conditions when bats are most active. TransAlta has engaged recognized bat experts at a Canadian university to participate in the research program.

To read the Executive Summary in its entirety, please click here.

For more information about past research we’ve done relating to bat mortality, please click here.