The latest of many avian studies at wind farms has been released, a heavy-duty look at bird and bat kills at the new Maple Ridge wind project in upstate New York. The results?
The detailed language from the Maple Ridge report provides some very interesting insights:
People/agencies who reviewed the proposed scope of work [for the study] included staffers from the U. S. Fish and Wildlife Service (USFWS), U.S. Army Corps of Engineers (ACE), Environmental Design and Research (EDR), New York State Department of Environmental Conservation, developers (PPM and Horizon), and others. Representatives from some or all of these groups have been included in a Technical Advisory Committee (TAC), which has the responsibility of reviewing and commenting on progress reports, annual reports, and other updates from this project.
This is typical of wildlife studies at wind farm sites. Studies are often attacked by anti-wind groups on grounds that they are carried out by consulting firms that are supposedly pro-industry. However, a Technical Advisory Committee with government agency experts who have no vested interest is a common practice.
The methods used include searches under turbines in concert with studies of carcass removal rates (scavenging) and searcher efficiency rates.
Again typical: the firm conducting the study runs tests to determine how quickly birds and bats are removed from the site by predators and how good the individuals doing the ground searches are at finding dead animals.
The Maple Ridge project currently consists of 195 1.65-MW turbines, for a total of 322 MW of nameplate generating capacity. Each turbine is approximately 400 feet (122 meters) in height.
As with most turbine facilities across the United States, the numbers of fatalities of night migrants was fairly low at the Maple Ridge facility. Determining the exact number of night migrants is difficult, however, as the birds involved may be resident breeders. The numbers were especially small in comparison with fatality rates of these birds at tall, guyed communication towers in the Midwestern and eastern United States where fatalities sometimes involve hundreds or even thousands of birds in a single night or migration season.
Why are the numbers so low? We don't know for sure, but one major reason appears to be that turbines are lighted differently than communications towers: turbines have red flashing (strobe) lights, while communication towers also have steady-burning red lights. The steady-burning lights appear to attract migrating birds on foggy nights. Also, communications towers have miles of guy wire, a major hazard for disoriented birds circling a light, and are greater in height.
Those towers have two types of Federal Aviation Administration lighting (steady burning red L-810 and flashing red incandescent beacons – L-864), multiple sets of guy wires, and are almost always in excess of 500 feet (152 m). We conducted tests of night migrant incidents found at lit and unlit towers for both the 30 7-day search sites and the 10 1-day search sites . . . If the red flashing beacons attracted birds to turbines, a disproportionately greater number of these fatalities would have been found at turbines with lights and, or large-scale, multiple fatality events would have been observed. We did not see a clear relationship between the numbers of night migrant fatalities and the presence of L-864 red flashing beacons on turbines..
The Maple Ridge report also comments briefly on the question of whether bird collisions with wind turbines affect overall populations (total numbers) of bird species:
The eastern population of the Golden-crowned Kinglet, which was found most often during searches, is estimated to be decreasing across the US but stable or increasing in the Eastern US. (Table 21). Given the overall population level of this species (estimated 34 million birds), it is difficult to presume that collision mortality at the Maple Ridge [wind farm] has a significant adverse effect on population levels, even with respect to cumulative impacts of fatalities from many wind plants.
The population of the second most common find (Red-eyed vireo) is listed as increasing, with an estimated overall population level of 140 million. The only two species listed as significantly decreasing are the Red-winged Blackbird and the Common Grackle, both very common and wide ranging species.
Wind turbines remain the single most thoroughly studied of all sources of human-related bird mortality--see, for example, the WEST, Inc., wind/avian studies collection. Thousands of birds do die in collisions (with thousands of wind turbines) at wind farms across the U.S., but it is clear that wind farms remain an insignificant threat to birds, and that birds and wind power--even large amounts of wind power--can coexist. A recent National Academy of Sciences report found that in 2003, wind turbine kills amounted to less than .003% (three of every one hundred thousand) human-related bird deaths. At the same time:
Wind power challenges our ability to be numerate, to maintain perspective, to be rational and not allow the perfect to be the enemy of the very, very good. I believe how we deal with it will determine whether we are indeed up to the task of ending global warming.