We’ve all heard the media hype about birds being killed by wind turbines. It’s one of the few downsides to wind energy. But is it true? For some, this is a legitimate concern, while others brush it off as anti-wind FUD. With climate change and deforestation killing off wildlife at an alarming rate, it makes sense to wonder if turbines are threatening wild animals, even if they’re meant to help us go green and save the planet. It’s definitely a question worth asking. In this article, we’re going to break down whether wind turbines are actually a threat to birds, how many birds are being killed, and what researchers are doing to make wind energy safer for airborne wildlife.
Bird Mortality and Wind Turbines
It’s easy to see why wind turbines would pose a threat to birds. They’re massive structures, and their blades are constantly rotating several meters up in the air. The tip of a blade can reach speeds well over 100 miles per hour. While wind turbines seem rather non-threatening, they’re pretty dangerous objects, especially to airborne wildlife. There are two ways that wind turbines can potentially harm or kill birds; by a head-on collision or via barotrauma.
From afar, the blades of a wind turbine appear to be rotating at a smooth, slow pace. But the speed of a rotating object increases the further away you get from the center. So the tip of a blade on a wind turbine can top out at 170 miles per hour. That’s pretty fast. It also poses a potential threat to birds. Birds of prey, who tend to focus on the ground when looking for a meal, can be easily killed by a rotating blade.
The high speed of the blades as they cut through the air poses another problem; changing air pressures. The size and speed of the blades cause large changes in air pressure in the immediate vicinity of the turbine. This can cause barotrauma, where a sudden change in pressure causes injury to the respiratory and pulmonary systems. Since birds are known to fly at high altitudes, their bodies are built to withstand large changes in air pressure. Bats, on the other hand, aren’t equipped to handle those changes. Wind farms near bat migration routes have seen high mortality rates.
Dispelling the Myths
While wind turbines do pose a threat to birds, it’s not as bad as the media would have you think. On a large scale, wind turbines are a minor threat. The benefits provided by wind energy far outweigh the potential risks to wildlife, especially when you consider habitat destruction and the global shift in climate caused by the fossil fuel industry. Deforestation and climate change are a much larger risk to bird populations than wind turbines. Bird advocacy groups like the Audubon Society have even put out statements in support of wind energy, recognizing the much larger threat that climate change poses to birds.
The danger to birds from wind turbines is actually very localized. Certain wind farms definitely pose a threat to birds, but that’s because the turbines are located right in the path of migratory routes. The debacle about the danger to birds was magnified from a select few wind farms which saw extraordinarily high mortality rates. Researchers took average bird mortalities from these select few locations and applied them to all wind farms, resulting in an alarmingly high amount of bird deaths. These statistics aren’t the norm. But there is one wind farm, in particular, that is notorious for birds deaths; the Altamont Pass Wind Farm.
Altamont Pass Wind Farm
The Altamont Pass Wind Farm is located in the Diablo mountain range in Northern California, just a few hours away from San Jose. The wind farm was one of the earliest wind farms in the US, with construction starting in the 1980s. At one time, it was the largest wind farm in the world in terms of capacity. The Altamont Pass has a capacity of 576 MW and still has one of the highest concentrations of wind turbines in the world.
The fear around wind turbines killing birds started at Altamont Pass. The area is unique because it’s smack dab in the middle of migratory routes for numerous bird species, including several species of songbirds, raptors, and the endangered California Condor. Over 4,000 birds are killed at the Altamont Pass Wind Farm every year, and over 1,000 are estimated to be raptors and birds of prey.
The Altamont Pass Wind Farm is unique for a number of reasons. First, it’s in the middle of migratory routes and prime bird habitats. The area has a high concentration of birds and supports a high level of biodiversity. Birds of prey are known to frequent the area to hunt the California Ground Squirrel. Second, the Altamont Pass Wind Farm uses outdated turbine designs known to attract birds. Many of the turbines use lattice towers, which are great for supporting bird nests. Unfortunately, these factors have led to an unsurprisingly high bird mortality rate.
The Altamont Pass Wind Farm has had a profound effect on the bird populations in the area. Northern California has seen an 80% decline in golden eagle populations. There aren’t any more known nesting sites in the Altamont Pass region, despite being a prime habitat for the species.
Organizations like the Audubon Society are working with researchers to make Altamont Pass safer for birds. Outdated turbines are being replaced with newer, bird-friendly models. Bird specialists also monitor endangered species like the California Condor and maintain open communication with the wind farm operators. They have shut-down protocols in place where turbines are temporarily stopped in the event that birds enter the area. There are also bird radar devices that scan the horizon for approaching flocks of birds. The efforts to reduce bird mortality have worked, reducing deaths by over 50%.
So, How Many Birds Are Killed by Wind Turbines?
As for how many birds are actually being killed by wind turbines, that’s a hard question to answer. As of right now, researchers only have estimates based on a few locations. The estimates can differ wildly depending on the methods used. Estimates can range from 10,000 to over a million per year. But why are the numbers so different?
This can be attributed to a few factors. One of the main reasons is that researchers took the numbers from wind farms with high mortality rates, like the Altamont Pass Wind Farm, and applied it to wind farms all over the world. The conditions at the Altamont Pass are unique and not applicable to other wind farms.
Second, not all bird deaths are counted. Human observers at high mortality sites have a high margin of error, which was shown when canine observers were used and found larger amounts of dead birds.
Third, the methodologies used differ between studies. Some researchers only count bird collisions, while others count birds who were killed by power lines which may be associated with wind farms. Transmission lines are a big threat for birds, and some researchers included deaths from transmission lines into the overall count toward wind turbines, even though transmission lines for all energy sources pose a threat.
Even at the highest estimates of over 1 million birds per year, the deaths from wind turbines are nowhere near the number of deaths from other sources. In the past few hundred years, we’ve lost bird species like the Dodo, Great Auk, and the Passenger Pidgeon, and this was before the advent of wind energy. So, what is it that’s really killing the birds?
What’s Really Killing Birds?
Since 1970, bird populations have declined by about three billion. That’s a whole lot of birds. Forests alone have lost one billion birds. Grasslands have seen over a 50% reduction in their bird populations, and many coastal seabirds have had their populations reduced by a third.
The largest threat to birds by far is habitat destruction. Many bird habitats have been wiped out by human development. Rainforests across the world are in danger, and these ecoregions are known biodiversity hotspots, especially when it comes to birds. Many species have been pushed toward extinction as their natural habitats are replaced with farms, cities, and factories.
In other areas, habitats aren’t outright destroyed but fragmented. This is when human development breaks apart natural habitats. This makes it so wildlife are forced to cross through human habitats, where they come into contact with other dangers. Tens of millions of birds are killed every year by human-caused hazards like cars, power lines, and large buildings.
Pesticides and toxins are another large threat to birds. Birds exposed to pesticides die of illness when they eat contaminated foodstuffs. Songbirds, owls, and eagles are especially high risk as they live in prime agricultural areas. Toxins like lead are also dangerous to birds. Lead buckshot used for hunting has poisoned large numbers of several bird species, like the endangered California Condor. Lead poisoning is one of the number one threats to the bird, and they were declared extinct in the wild in 1987. An aggressive conservation program has restored their population to over 500.
Wind turbines can pose a threat to birds, but it’s all about design and location. The Altamont Pass Wind Farm is unique because its located in a major bird habitat, and the older lattice designs attract birds looking for a place to nest. It isn’t the norm across the board, even though the issue does deserve some attention. What’s really killing birds are much larger issues like climate change, habitat destruction, and pesticides. Ironically, wind power is the solution to some of these issues. Still, researchers are finding ways to ensure that wild birds aren’t put at risk by the massive rotating blades while passing through a wind farm. And if turns out that wind turbines do become a large threat to bird populations, then maybe bladeless wind turbines will fix the problem?
Frequently Asked Questions
Theoretically, yes. Wind turbines are large rotating structures. Blade velocity at the tip may reach speeds well over 100 mph. But the danger to birds comes from the placement of a wind turbine. Wind farms placed near migratory bird routes pose a large threat. Still, wind turbines are a much smaller threat to birds compared to habitat loss and human development.
Researchers estimate that between 10,000 and 1 million birds are killed by wind turbines every year. The large difference in numbers is due to the different research methods. Some researchers took bird deaths from high mortality wind farms and applied them to wind farms all across the world.
The Altamont Pass Wind Farm is dead in the center of a prime bird habitat and migration route. The outdated turbines also use a lattice structure which attracts birds looking to roost. This has lead to the wind farm having an extremely high mortality rate.
The biggest threats to birds are climate change, habitat destruction, and human development. Since 1970, bird populations have declined by about 3 billion worldwide. This is a trend that predates wind energy.
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