Montana Audubon

Montana Audubon works at the local, state and national policy levels to protect our natural heritage.

Wind Energy

Wind power is an important part of a clean and sustainable energy economy. However, proper siting of wind turbines and infrastructure is important to avoid damaging habitat and wildlife resources.

Montana Audubon works to ensure that wind energy producers do not locate their facilities in critical habitat for birds or other wildlife. Collisions with turbines can kill many birds outright, and wind turbines are known to negatively affect local bat populations. The network of roads, turbines, and other structures displace birds and other creatures from a wide swath of habitat.

To guide us in our work, Montana Audubon has adopted a Wind Energy Siting Policy Guidance Document.

More Wind Power Development Coming to Montana:

Montana ranks #1 for class 3 or better wind and major projects are currently planned for development throughout the state. Since they do not require permits in Montana, it is difficult to track where projects are being built. However, based on several sources, we have created the following map  of developed and proposed commercial wind projects:

Commercial Wind Farms in Montana (4/2018):


Note: capacity of wind farms is measured in megawatts (MW) produced. In addition, wildlife mortality studies generally measure impacts to wildlife by the numbers of animals killed per MW per year.

To download this map and the list of wind farms as a pdf, click HERE.

Impacts to Montana Wildlife:

Commercial wind development can impact wildlife, especially if the project is located in critical habitat. The main impact from wind farm development stems from habitat fragmentation, where wildlife is displaced either because the habitat is developed/altered by the wind farm OR because the wildlife species avoids areas that are fragmented. In addition, some mortality occurs to birds and bats from collisions and other factors. The information below summarizes our knowledge about potential wildlife impacts in Montana.

Habitat Fragmentation:

Photo by FWP.

Habitat fragmentation occurs when wind farms—and their associated roads, power lines, and other structures—displace wildlife. The effects of habitat fragmentation go far beyond the immediate “footprint” of the wind farm, because some wildlife—particularly prairie species—will avoid areas with high towers. A solution is to keep these projects close to established roads, cropland, and other developed areas—and away from large blocks of crucial wildlife habitat. The Greater Sage-Grouse is one species that appears to be impacted by habitat fragmentation—it needs large landscapes. Specifically, female sage-grouse with young tend to avoid areas with towers, roads, and similar development.

Commercial wind facilities in Montana use between 20 acres (one of five small operational wind projects near Two Dot) and 50,000 acres (Glacier Wind Farm near Shelby).

Bird Collisions with Wind Turbines:

Horned Lark. Photo by Bob Martinka.

Resident and migratory birds can collide with wind turbines.

Nationally, studies show that wind farms kill between 3 to 6 birds per MW per year for all species. This fatality rate is considered ‘acceptable’ for a wind project because it will not impact bird populations. Although there are very few bird studies conducted by wind companies released to the public in Montana, we do know about the study results from two wind farms: at Judith Gap Wind Farm bird fatalities ranged between 2.2 – 3.0 birds/MW/year; at Spion Kop Wind Farm bird fatalities ranged between 0.31 — 1.6 birds/MW/year.

A positive aspect about newer wind turbines is that they do not have places for birds to perch or nest because the turbines no longer are lattice structures. In addition, transmission lines between turbines are currently always buried underground. Fewer birds perching on turbines, power lines and poles, means a reduced potential for birds striking turbines. This is especially true on the prairie, where perches are particularly attractive to everything from meadowlarks to raptors. Since this design change, the number of birds killed by wind turbines has decreased significantly.

Bats and Wind Turbines:

Hoary Bat. Photo by Kristi DuBois

Bats also collide with wind turbines. There is some evidence that bats may be attracted to the moving blade of turbines, particularly at lower wind speeds. Nationally and in Montana, bat fatality rates are generally much higher than bird fatality rates: nationally bat studies ranged between 1 bat/MW/year to 30 bats/MW/year.

At Judith Gap Wind Farm, studies indicate that bat fatalities ranged between 4.8 and 8.9 bats/MW/year; at Spion Kop Wind Farm, bat fatalities ranged between 2.6 and 5.5 bats/MW/year.

In addition to collisions, there is at least one other way that bats are killed by wind turbines: if bats get too close to the turbine blade, they can be sucked into the lower pressure area following the blade. This low pressure area can kill bats by causing their lungs to expand like a balloon. Newer studies about bats and turbines suggest that “barotrauma” is unlikely to cause mortality.

Although bat fatalities at wind farms vary greatly, we do know that:

  • Migratory tree roosting bats are the most common bats killed by turbines in Montana. Specifically, most of the bats killed are either hoary bats (Lasiurus cinereus) or silver-haired bats (Lasionycteris noctivagans), which are boreal forest bats. These bats are primarily killed during their August to September migration south.
  • In other states, Eastern Red Bat (Lasiurus borealis), which are also found in Montana, are commonly found to be vulnerable to wind turbine mortality.

One conservation measure being considered by wind farms to lower the number of bats killed is to stop the turbines from moving at lower wind speeds. For example, if wind turbines are prevented from moving until the wind speed is 20 feet/second, it can greatly reduce bat fatalities.

Wind Facility Regulation:

Currently Montana has virtually no ability to regulate wind farms. Consequently, wildlife concerns may only be addressed if a project is located on public land. When this happens, an environmental review must be conducted under either the Montana Environmental Policy Act (MEPA) for state land or under the National Environmental Policy Act (NEPA) for federal land (Forest Service, BLM, etc.). These environmental reviews usually allow the public to comment on the proposed project.

As mentioned above, most wind farm companies do not release any research information to the public for review, so it is virtually impossible to determine wildlife impacts from various wind farms.

Modern Wind Turbine Technology:

Wind turbines used at Montana wind farms produce about 1.5 Megawatts (MW) of energy. In general, these 1.5 MW turbines are:

  • Height of Tower: 250 – 300 feet;
  • Blade Length: 100 – 130 feet;
  • Total Height of Turbines: 390 – 400 feet;
  • Wind Speeds Used by Turbines: Wind turbines usually start spinning when the wind is stronger than 6 – 7 miles per hour (mph); they stop spinning when wind speeds are above ~ 50 mph.
  • Speed of Turbines: The tips of the blades spin at the rate of 140-180 mph under normal operating conditions.

The good news about these newer turbines is that they don’t have lattice areas for birds to perch and transmission lines between turbines is nearly always underground. These two design improvements have reduced the number of birds killed by turbines significantly.

The largest turbine currently being used in Montana appears to be 2.3 MW turbines used at the Greenfield Wind Farm. Larger turbines are currently being used in other states.

Learn More about Wind Energy:

Here are three good sources of information about wind farms and wildlife:

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