Wind

Wind farm in Xinjiang, China. Photo credit: Lim, 2005

CONSTRUCTION

As far as land use is concerned, wind energy has one of the smallest footprints and therefore causes, comparatively to solar, hydroelectric, and wind, the least ecological damage. Nevertheless, the actual construction of the facility is often the most damaging step of the process and has multiple detrimental effects on wildlife.

Turbine Installation & Land Manipulation

Wind turbine construction in Surprise,
Arizona. Photo credit: Stepp, 2010

Solar facilities often functionally cover very large areas of land, however the actual turbines generally do not physically cover more than 10% of that land, and often no more than 5% (Arnett, 2007). Unfortunately, the construction process alone can compact soils and destroy vegetation because it requires accommodation of large cranes and trucks as well as equipment storage facilities. Some sites also need grading, which causes further vegetation damage as well as outright vegetation removal. This often takes the form of deforestation, as wind farms need wide, open areas to be effective. Surprisingly, forest clearing has actually shown to have positive impacts on certain species of bats. Evidently some species use small clearings to forage, and wind farm construction was making these small clearings possible (Arnett, 2007). They also experienced beneficial edge effects from the clearing through increased insect congregations, which allowed them to better catch and feed on the insects while in flight (Arnett, 2007). Unfortunately, these benefits are only present so long as the bats’ roost trees are not cut down.

Roads

New wind farms also require the construction of roads, which fragments otherwise suitable continuous patches of habitat and decreases the ability of certain species to disperse, particularly large mammals. This barrier to dispersal reduces the amount of gene flow and causes populations to become genetically isolated and lose genetic diversity. Some animals like the bobwhite quail, wild turkey, and various predators have actually been found to use the roads for better dispersal, though these species are then subject to mortality via vehicle collisions (Kuvlesky, 2007). In a study about wind farms' effects on bats, researchers found that some species used linear landscape elements (i.e. roads) to forage, commute, echo-orient, and protect themselves from predators (Arnett, 2007). However, again, these benefits are only received if the populations’ roost trees were not razed in the construction process. Construction of roads also causes greater disturbance and therefore increases the landscape’s vulnerability to introduction and expansion of invasive species (Kuvlesky, 2007).

OPERATION & MAINTENANCE

Avoidance

Le Conte's Sparrow, a grassland bird that often avoids wind
farms. Photo credit: Lasley, 2008

One of the most interesting – and most common – reactions of species to wind farms is avoidance of the site. While the footprint of the actual turbines and their accompanying facilities is quite small, researchers have seen that species diversity and abundance near the turbines was not particularly high. However, it increased as they got farther away from the site and, at 100 meters, species diversity and abundance leveled off (Arnett, 2007). Beyond that point wildlife seemed unaffected. It was proposed that the animals were avoiding turbine noise (a single turbine emits a noise similar to that of a running washing machine (Electricity from Wind, 2000)), maintenance activities, traffic, and were finding the immediate areas to have decreased effectiveness due to the gravel and concrete areas surround the turbines – areas that were once natural habitat (Arnett, 2007). These avoidance efforts have been seen for all shapes and sizes of wildlife – from grassland birds to large mammals, so while turbines are not directly harming large portions of a landscape, they are causing habitat loss due to species’ need to avoid these areas because of degraded habitat quality. Unfortunately, many areas that are ideal wind farm locations are also grassland birds’ best habitat, that is, locations with elevated or flat grasslands with few vertical obstructions (Arnett, 2007). As grasslands are one of the most degraded landscape types in the world, this pushes already threatened species into even smaller landscapes. Interestingly, grassland birds are also avoiding wind farms supposedly because wind turbines and transmission towers provide perches for predatory birds. Grassland birds then evacuate the surrounding areas so as to escape predation (Lieberman).

Collisions

Golden eagle, one of many species of birds affected
by wind turbine rotors. Photo credit: Golden Eagle

Wind energy is notorious for one particular aspect of wildlife impacts, and that’s collisions between birds and turbines. Raptors have gotten the most attention purely because they sustain the most losses, but golden eagles, red-tailed hawks, American kestrels, burrowing owls, and many species of bats also feel effects (Arnett, 2007). In response to public attention, new wind farms have begun to implement turbines that are taller with shorter rotors, which are shown to have fewer effects on bird populations. This means that most of the cases of large bird mortality rates have been in wind farms that use outdated turbines, and hopefully this issue will soon become a thing of the past. The effects are also incredibly variable depending on local bird population density, as areas with the highest densities may see large fatality rates, while most farms see next to none (Arnett, 2007).

Turbine rotors, unfortunately, are not the only things causing bird mortality. Transmission lines on wind farms have also been responsible for fatal collisions and pose electrocution risks to all flying organisms (Kuvlesky, 2007).

Photo credit: What Are Some of the Main Forms of Alternative Energy Used Today?

Offshore Farms

With the increasing abundance of offshore wind farms, researchers have begun to look at the effects they have on wildlife compared to terrestrial farms. Many of the effects appear to be the same: loss of habitat due to displacement from avoidance and collisions with turbines. However, offshore wind farms have greater effects on migratory birds, as lateral farms (in which the turbines are arranged in a line, rather than a cluster) act as a barrier and cause fragmentation of the habitat network (Arnett, 2007). Alternately, there has been some evidence that birds use the turbines as perches in the absence of natural islands, and there is yet to be any evidence showing that fish populations are negatively affected, though further study needs to be done on the matter.

Original Figure, stats from Top Ten Wind Power Countries, 2011