Do wind turbines kill birds?

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The Altamont Pass in California is known for its outdated turbines and high avian mortality rate.

It's easy to see why wind turbines are at least potentially hazardous for birds: Massive blades with tips spinning at up to 179 mph (80 meters per second), hundreds of feet (at least 30 meters) in the air, are an obvious problem for anything flying near them [source: MIT]. The fact is, birds do fly into the path of the blades and die a grisly death. Most of the affected birds are songbirds, and about 10 percent are birds of prey like raptors [source: ABC]. It's the raptors that started all the protests, when hundreds of carcasses were found strewn across Northern California's Altamont Pass wind farm.

Bird conservationists took great interest, and the misconception that wind turbines pose a major threat to bird populations grew from there. By applying the mortality rates at Altamont Pass to every wind farm in the United States, the bird-mortality figures became extremely inflated. In fact, Altamont Pass is a unique case of a wind farm that is truly a significant hazard to birds.

Altamont Pass is different for two main reasons: turbine location and turbine design.

There are more than 4,000 wind turbines at the Altamont Pass energy farm in California. It's one of the first wind farms in the United States, and its 20-year-old turbines are accordingly out-of-date. Their design has long since been abandoned: Latticework blades with small surface area are far from efficient for energy generation, and far from safe for birds. The lattice structure actually attracts large birds, because the frame makes for an excellent perch. Large birds like raptors are drawn to the blades, and collision rates are high as a result.

The other design issue is the blades' low surface area, because less surface area means the blades have to spin faster to turn the electricity-generating turbines. The faster the blades spin, the more dangerous they are to birds flying near them. It's unlikely that a bird that finds itself in the vicinity of the blades could ever make it through when they're spinning so fast.

As if this weren't enough to make old wind farms a bird nightmare, the Altamont Pass power plant was built smack dab in the middle of a major migratory route for large birds. The area also houses the world's largest single population of golden eagles [source: USA Today].

The total for all wind farms in the United States, is 140,000 to 328,000 per year according to a 2013 estimate [source: Loss, et al.]. ­Even though up to 1 billion birds die each year by flying into windows, no one is brushing off the tens of thousands of turbine-related deaths every year. So what are we doing to lower that number? On the next page, we'll see what changes are being implemented to save the birds.

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Newer turbines, like those on Tug Hill in New York, have a larger surface area and cause fewer bird deaths.

In the past couple of decades, turbine designs have changed dramatically. Turbine blades are now solid, meaning no lattice structure to attract birds looking to perch. Also, the blades' surface area is much larger, so they don't have to spin as fast to generate power. Slower-moving blades mean fewer bird collisions.

Perhaps the biggest change in wind-farm safety, though, has to do with location. Now, all new turbine proposals are reviewed for ideal, bird-friendly placement. Wind farms cannot be built in migratory pathways, in areas with high bird populations, or in areas with special features that could possibly attract high bird populations in the future. Also, the growing trend toward offshore turbine construction bodes well for birds, since offshore wind farms have fewer bird collisions than land-based farms.

Possibly the greatest indicator that wind turbines are not, in fact, bird-o-matics, is the growing number of endorsements by bird conservation groups. The American Bird Conservancy supports wind power with the caveat that bird-friendly placement and design be primary factors in construction [source: ABC]. The Wisconsin Bird Initiative states that wind turbines have a "low impact" on avian mortality compared to window glass and communication towers [source: WBCI]. And in 2006, the Audubon Society gave its figurative seal of approval to the American Wind Energy Association. The president of the national organization is quoted by Renewable Energy World as stating, "When you look at a wind turbine, you can find the bird carcasses and count them. With a coal-fired power plant, you can't count the carcasses, but it's going to kill a lot more birds" [source: REW].

Of course, zero turbine-related bird deaths would be the best-case scenario, but as far as energy production goes, that seems to be an unrealistic goal. The best we can hope for is smarter placement of wind turbines and more bird-friendly design in order to further reduce the number of bird deaths resulting from one of the best alternative energy sources available right now. Altamont Pass, for its part, is in the process of slowly replacing its turbines with newer models.

For more information on wind energy and birds, fly to the links on the next page.