Calgary's Vision Quest Windelectric is wrapping up a study of bird impacts at its Castle River Wind farm -- and the preliminary results show low mortality rates over two years. The Castle River site is located in the foothills of the Rocky Mountains in southern Alberta, an area that "has many species active many times of the year," says Vision Quest's Justin Thompson. During the first year of the study, when 23 turbines were installed, there were four bird deaths. In the second year, when the plant had reached its full complement of 60 machines, 12 bird deaths occurred. "The numbers were quite low, which is encouraging," said Thompson. "They are also consistent with international studies." The study is the first comprehensive look at bird interaction with turbines at a Canadian wind farm, something Vision Quest is repeatedly asked for during its community consultations for new developments. "People don't like the references we use from Europe or the US," he explained. "We have a Canadian study now, that we haven't had before, that demonstrates that birds in Canada aren't really that much different than birds in the US or Denmark or anywhere else." The study also observed how different bird species interact with the turbines, said Thompson. Raptors tend to avoid the turbines altogether, while passerines will travel within the wind farm below the rotor height. Waterfowl tend to fly up and over, even when they approach the turbines at a low level coming out of the river valley. This type of information, said Thompson, can be incorporated into project planning. "Understanding species-specific behaviour may be very helpful in the future in how we develop wind farms," he added.