Significance of Wind Turbines on Bird Mortality

Birds flying over a field at dawn in winter. J. Marijis. Shutterstock

Birds flying over a field at dawn in winter. (Marijis, J.)

Jacqueline Kennedy- Environmental Science, Gina Chesmore- Animal Science, Johanna Smith- Animal Science

As scientists decipher threats to human health and the ecosystem, they look to birds to find indicators of these threats. Particular bird species are susceptible to changes in the environment, making them good indicators of environmental conditions. Rachel Carson was among one of the first scientists to study this linkage; she observed the impact of DDT on bird populations after World War II, when the compound was widely used as a pesticide. If it were not for birds, the Environmental Protection Agency would not have discovered the negative effects of the pesticide so readily. As a result of these findings the United States banned DDT in 1972 (Beard, 2006). Another example of birds as an indicator species is the use of canaries in coal mines to detect carbon monoxide and other toxic gases, since the birds are more sensitive to toxins and would show signs of poisoning before the miners did. Other examples include mortality of crows as an indication of West Nile Virus and sick vultures in Asia due to diclofenac, a drug administered to livestock in order to help them heal from wounds (Balmford, 2013). In order to continue to utilize birds as an indicator species, we must find ways to preserve their populations, as they are a necessary part of the food chain that can lead to scientific discovery in regards to both human health and ecosystem health.

In addition to acting as bio-indicators, birds play a crucial role in the environment around us; they aid in pest control and seed dispersal (The Importance of Birds, 2001).  Birds contribute to pest control by consuming mosquitoes, Japanese beetles, European corn borer moths, among other insects. These bugs are notorious for invading plants and bothering humans, gaining their reputation as pests. Birds remain an important part of the environment by aiding in the spreading of seeds and dispersal of plants.  Birds that eat fruits spread seeds via their droppings to other locations (The Importance of Birds, 2001).  Some species, such as the hummingbird, polinate plants by transporting pollen from one flower to the next on their beaks and feathers (The Importance of Birds, 2001).  This creates diversity in our plant flora and generates food sources for many animals (The Importance of Birds, 2001).  Birds generate diversity in plant species as well as maintain healthy environments for existing plants. They are a crucial link in food chains and webs that exist within the ecosystem.

Although birds are a vital part of our ecosystem, many people overlook this importance. Birds are often overshadowed by more charming or affectionate animals, such as common household pets.  According to the American Pet Products Association only 6.1 million U.S. households own birds, while 54.4 million U.S. households own dogs (American Pet Product Association, 2016). Similarly, Gallup Magazine organized a poll in 2006 and discovered that 73% of American pet owners have dogs, while only 5% of pet owners have birds (Newport et al., 2006). This unequal dispersion of pet ownership is partially attributed to a concept known as the “oxytocin-gaze positive loop.” As Nagasawa et al. (2015) explain, human and canine create a unique emotional connection when engaging in unbroken eye contact, causing both species to secrete oxytocin, the nurturing hormone. Female mammals secrete this hormone to produce more milk and bond to their babies. In contrast to the relationship between people and dogs, there is no “oxytocin-gaze positive loop” effect between people and birds. Although biology naturally gears our sensations to favor the company of mammals, it is worthwhile to realize the importance of birds and the potential threats they face.

Wind turbines, the large outdoor fan-shaped structures that generate electricity from wind power, may pose a future threat to bird populations. Unlike fossil fuels, wind turbines are generally viewed as a source of “clean” energy, meaning that toxic pollutants are not produced and released in the energy generation process (Daniels, 2015). Ironically, they also have a reputation for being environmentally friendly, despite their impact on birds. Birds and wind turbines are often found in the same vicinity, which may lead to future significant impacts on bird populations.  Are these living, breathing, bio-indicating bird species being negatively impacted by wind turbines?

Research does not suggest that wind turbines pose a significant effect on bird populations in comparison to other threats.  Direct strikes with windows are estimated to cause 97 to 976 million bird deaths per year (Sibley, 2003).  Other factors contributing to significant bird deaths include feral cats, high tension wires, and pesticides (Sibley, 2003).  Wind turbines may kill only up to 33,000 birds per year, a miniscule number compared to the millions killed by window strikes (Sibley, 2003) Although wind turbines are currently not the largest hazard to birds in comparison to other hazards, it is important to look at the projected growth of the wind turbine industry when assessing how they might affect birds in the future.

From 2008 to 2015, the wind capacity of the United States has increased from 16,702 megawatts to 74,472 megawatts. In 2015, the United States installed 77% more megawatts of wind power in the United States than the year previous. This large increase in the reliance of wind turbines is due to wind energy development costs dropping 66% in the past six years (Pyper, 2016). The technological innovation and operational improvements of wind turbines has driven the costs down and allowed development to occur in regions with lower wind speed that were not previously accessible for wind power. Advancements in production of wind turbines has allowed manufacturers to design taller towers and turbines. Today the average turbine is atop an 80 meter tower, whereas years ago the average wind tower was 65 meters tall (American Wind Energy Association, 2013). The United States is looking to further this reliance on wind power. The United States Department of Energy has a goal to generate 20% of the nation’s electricity demand by 2030 and goes into technical detail about this in the Energy Department report 20% wind Energy by 2030: Increasing Wind Energy’s Contribution to U.S. Electricity supply. This projected rise in wind energy will increase the number of wind turbines installed per year from 2000 per year in 2006 to 7000 per year in 2017 (U.S. Department of Energy, 2008). The drastic increase in turbine installation per year could lead to a number of problems for bird populations both physically and behaviorally.

This increase in wind energy is problematic, as it is likely to amplify the existing effects turbines have on birds. With no standardized method of pre-construction monitoring prior to turbine placement, companies are free to place turbines in areas with a high bird density.  The pre-monitoring for wind turbines that is done now mainly to assesses the wind power available in that area, and does not concern wildlife surrounding the zone (Green Energy Ohio).  When assessing areas for new wind farms, there are many factors that must be considered.  Wind farms are placed in areas where the wind is strongest and most steady (Shere, 2011).  Wind farm developers utilize wind forecasters to interpret data that helps predict future wind trends for a certain area (Shere, 2011).  These new wind farm plots are monitored for a year or more in order to collect adequate amounts of data (Shere, 2011).  The most important contributing factor when looking towards future wind farms is the placement of erected turbines.  This includes layout of the turbines, geographical location, and turbine height/blade size (Loss et al, 2013).  If all of these factors can be altered in favor of birds, wind turbines will have less of a negative impact on these animals and can continue to be a clean energy source for the future.  In particular areas turbines do not allow enough space for migratory birds to pass through undisturbed.  Turbine height is another factor to consider, as taller turbines with longer blades have more of an effect on birds (De Lucas et al. 2008). If these factors are not controlled with pre-construction monitoring, the projected increase in the number of wind turbines could cause significant effects on bird populations in the future both physically and behaviorally.

Physically, wind turbines facilitate physical problems for birds by causing disturbance, injury and mortality. Mikołajczak et al. (2013) draw on the disturbance aspect, arguing that noise pollution generated from wind turbines causes stress and reduced weight gain in geese. To measure stress, they investigated the cortisol levels of the geese’s blood. Cortisol was measured because it is the hormone synthesized by the adrenal glands in times of stress. They determined that after 48 hours of exposure, geese 50 meters away from the wind turbine had twice the concentration of cortisol in blood than the geese that were 500 meters from the turbine (Mikolajczak et al. 2013). It was apparent over the course of 17 weeks observed, that the concentration of cortisol in the blood of the birds “increased with the time of exposure to the immediate vicinity of the wind plant” (Mikolajczak et al. 2013). The authors also note that “the cortisol concentration in the animals from group II was higher than the control concentration, which may therefore suggest that the distance of 500 m from the turbine is still not a safe distance” (Mikolajczak et al.  2013). This signifies that any presence of wind turbines at all has an influence on stress levels.  Loss et al. (2013) provide evidence of wind turbines causing an increase in mortality, when comparing annual bird fatalities per single turbine over the years. According to Loss et al. (2013), annual mortality has increased from 0.64 to 6.20 birds per turbine.

In addition to physical difficulties, stress also cause behavioral issues for birds that stems  from presense wind turbines. Mikolajczak et al . (2013) linked the exposure to chronic stress to the behavior of less physical activity by the birds of group I, the group 50 m from the turbines. The authors suggested that a likely result from exposure to chronic stress is a lack of movement, stating “birds of group I, for the most part, remained in a compact group and showed less physical activity, while individuals from group II moved freely” (Mikolajczak et al ., 2013). In the same study by Mikolajczak et al. (2013), the authors also found that geese from the group closest to the turbine had lower weekly feed intakes. As the weeks went on, the weight gap between group I and group II increased; group II began gaining weight more significantly than group I. The authors determine that “animals kept near the wind turbine had about 10 percent lower body weight than those kept at a distance of 500 m from the turbine” (Mikolajczak et al . 2013). This decrease in feed intake is also linked to the increased stress caused by infrasound noise emitted by the wind turbines.

In addition to reduced feed intake, noise emitted by wind turbines has a negative effect on the breeding success of bird populations. In a study that focused on territorial defense behavior of robins, the authors concluded that noise from wind farms “may affect [robins] ability to deter a rival, leading to expenditure of extra time and energy and to increased risks of injury and, as a consequence, reduced breeding success” (Zwart, Dunn, McGowan, & Whittingham, 2015).  This chain of events shows how wind turbines can cause domino effects on the actions of birds. Increased expenditure of time and energy in deterring rivals may lead to consequences other than reduced breeding success as well, such as reduced feed intake. As wind farms are erected in greater numbers around the nation, we must ensure that these consequences are minimized.

The physical and behavioral problems caused by wind turbines generate a need for pre-construction monitoring to examine bird densities for optimal turbine placement in an effort to reduce these effects on bird populations.

In order to combat the potential increase in the number of physical and behavioral effects of wind turbines on birds, a number of pre-construction monitoring provisions should be introduced. Pre-construction monitoring will determine optimal turbine placement in order to minimize the negative effects of future wind farms. Each wind energy company in charge of turbine construction must perform location assessments of new turbine areas to determine how birds in that area will be affected. In particular, the companies must seek out locations that have low bird population densities in order to have a minimal impact on any particular species. When a company completes its pre-construction monitoring requirements, it will then receive a permit allowing them permission to erect the wind farm in that location under the standards permitted.

A similar implementation of allotting turbine permits has been employed by the New Jersey Department of Environmental Protection. The permittees must conduct a series of surveys before and after the site is constructed of both a potential wind farm site and a reference (control) site nearby. Their system has tiered levels of permits that are given out to appropriate locations with standard pre- and post-monitoring requirements for each tier. Tier levels are determined by the level of impact the particular location would have on bird populations and how many turbines will be erected on each site. Each tier has specific pre-and post-construction monitoring requirements. In particular, pre-construction survey requirements focus on certain bird species that are particularly susceptible to impact by wind turbines, such as migratory songbirds, migratory raptors, and breeding birds. Pre-construction monitoring must also take into effect bird densities in the potential wind farm area. Post-construction monitoring includes carcass searches, visual bird surveys, and radar studies (New Jersey Department of Environmental Protection 2009).

In order to ensure correct pre- and post-construction monitoring practices nationwide, a similar manual to the one issued by the New Jersey Department of Environmental Protection should be issued across the United States. It is vital to have a national standard restrictive mechanism for permitting that determines whether or not a location may be permitted and how many turbines a permittee may erect on a particular wind farm based on bird population impact.

Potential changes to future turbines are also a vital consideration in ensuring that future wind turbines do not negatively impact bird populations. Pre-construction monitoring can help determine what changes should be made to turbines in a particular area. For example, in an area with high bird densities during particular seasons, temporary shutdown of turbines may be a beneficial way to lessen the impact of the turbines on migratory patterns of birds.  Adjustments to tower height is also a strong consideration, as particular bird species of the area may keep a steady migratory height. If the turbines are built around the needs of the bird, the impacts will be lesser. Performing a series of precautionary steps before erecting wind farms is vital in ensuring that the impacts of wind turbines on birds stay minimal so future generations can utilize both the energy benefits from wind turbines and the ecosystem benefits of birds.

 Unfortunately, our plans require a fair amount of funding. State government will not be overjoyed to have yet another expense, and for this reason they may be reluctant to approve our proposal. In response to this, we bring forward the argument that preventative methods of bird collision and disruption would be infinitely more moral, inexpensive, and simplistic than attempting to restore bird populations if a devastatingly significant impact were to occur.

Although wind turbines do not pose a significant threat to bird populations right now, they do have negative effects on birds.  These negative effects could increase with increasing wind energy farms. In general, birds play an important role in the ecosystem and we want to make sure their populations remain healthy in number (The Importance of Birds, 2001).  In order to do so, the negative impacts of wind turbines on bird populations must remain controlled.  We are proposing a system that utilizes monitoring and assessments of areas where turbines will be placed in the future.  Our goal is not to knock down any existing wind farms, as that would be wasteful and could cause more disruption to the animals.  For future wind farms and turbine placements, the ideal area will be one of lower elevation, with naturally low bird densities, and shorter turbines with a smaller blade size (Powlesland, 2009). Wide corridors should be allowed between closely spaced turbines to limit collision fatalities and prevent barriers for both migratory and resident birds (Powlesland, 2009). Birds are key bio-indicators that can be very helpful in determining the health of our environment (The Importance of Birds, 2001). In order to ensure the health of our environment and bird populations, companies must use pre- and post-construction monitoring in order to ensure strategic placement and altered turbine type.

















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