U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3067

September 2016 Printed on recycled paper

Renewable Energy and Wildlife Conservation

Research to Understand Risks, 

Measures Impacts, and Inform Solutions

The renewable energy sector is rapidly expanding 

and diversifying the power supply of the country. 

Yet, as our Nation works to advance renewable 

energy and to conserve wildlife, some conflicts arise. 

To address these challenges, the U.S. Geological 

Survey (USGS) is conducting innovative research 

and developing workable solutions to reduce impacts 

of renewable energy production on wildlife. 
Understand

risks

Inform

solutions

Measure

impacts

 Understand Risks

Understanding risks to wildlife starts with good information

about each species of interest, including its distribution and 

habitat. Gaining such understanding often requires the discovery 

of basic biological and ecological information about each species. 

For example, knowing an animal’s diet, migration timing and 

corridors, seasonal behaviors, reproductive patterns, and survival 

strategies helps determine when and where it might be at greatest 

risk from energy development. Resource managers also benefit 

from research that characterizes the cumulative effects of energy 

development throughout a species’ range or over multiple 

generations. To get this information, scientists develop and use 

sophisticated tools for tracking wildlife across large distances, 

or for monitoring wildlife activity around energy facilities. This 

science helps identify which species and populations are at risk, 

and how and why they might be affected. This information is 

essential for discovering workable solutions to unacceptable risks.

 Guiding Strategy

The USGS provides scientific information and science-based 

options that government agencies and private industries can use 

as they strive to avoid, minimize, or mitigate impacts of energy 

infrastructure on wildlife and their habitats. Research goals 

range from identification of a specific local issue and options 

for response, to development of techniques to address nationwide concerns. Knowledge gained serves as a foundation for 

understanding impacts and creating workable solutions. USGS 

science allows for development of new or improved strategies to 

minimize impacts and make the national energy supply cleaner 

and greener. 

 Measure Impacts

The USGS develops tools, methods, and datasets so 

managers, regulators, industry, and the interested public can 

systematically and accurately measure the impacts of renewable 

energy developments on wildlife. This is essential for informing 

and prioritizing management actions. For example, managers and 

industry operators are using a statistical tool developed by the 

USGS to estimate wildlife fatalities at wind energy facilities (Huso 

and others, 2012). The USGS has developed a related tool for rare 

species and is adapting tools to other types of renewable energy 

facilities, including solar. Method and tool development commonly 

occurs by using energy facilities as study sites and working 

cooperatively with the energy industry and agency regulators.

Three interrelated goals (fig. 1) are:

1. Understand risks: Identify when, where, and why 

 wildlife shares space with energy facilities.

2. Measure impacts: Assess direct and indirect 

impacts to species and populations.

3. Inform solutions: Avoid or minimize impacts through 

technological fixes, management, and mitigation.

Causes of Bat Fatalities at Wind Turbines

Bats provide billions of dollars in economic benefits in 

the United States, such as suppression of insect pests in crop 

fields and pollination of important desert plants (Boyles and 

others, 2011). However, despite dozens of bat species occurring 

in the United States, the lives of most remain mysterious, even 

to the scientists who study them. Unprecedented numbers of 

bats began dying at wind power facilities around the turn of the 

millennium, creating an imperative to understand the causes of 

bat fatalities at wind turbines and ultimately find solutions to this 

new problem. The USGS consistently contributes to discovering 

the underlying reasons for bat susceptibility to wind turbines by 

closely studying the lives of the species most 

affected and how they interact with wind 

turbines (Cryan and others, 2014). 

Migratory tree bats, a group of bat 

species that migrate long distances 

and rely on trees for roosting 

throughout the year, comprise a 

majority of bat fatalities observed 

beneath wind turbines in the United 

States. Peaks in tree bat fatalities 

coincide with periods of migration 

and mating, strongly suggesting that a 

seasonal behavior drives risk. In flight, even 

echolocating bats perceive distant objects primarily through 

vision and can see in dim lighting conditions. The cumulative 

evidence indicates that tree bats might mistake wind turbines for 

trees in the dark—a potentially fatal case of mistaken identity. 

One solution may be to make turbines appear less like trees to 

bats, a ‘distant avoidance’ method the USGS is exploring by 

experimentally illuminating turbine surfaces with dim, flickering 

ultraviolet light that only bats can see (Gorresen and others, 

2015). Another solution being explored by the USGS is to make 

turbines less attractive to approaching bats by emitting highfrequency sounds that interfere with bat echolocation when they 

get dangerously close. The USGS aims for practical solutions to 

the problem of bat fatalities at wind turbines.

Figure 1. Three interrelated goals addressing renewable energy 

and wildlife.
0.2 0.4 0.6 0.8 1.0

Search coverage (a)

Detection probability (g)

Search interval (I) (days)

 0.05 

 0.1

 0.15 

 0.2 

 0.3 

 0.35 

 0.4

 0.45 

 0.5 

0.55

 0.6 

 0.25 

30

25

20

15

10

5

1

Take is defined in Section 3 of the Endangered Species Act as “harass, harm, 

pursue, hunt, shoot, wound, kill, trap, capture, or collect” any threatened or 

endangered species (Public Law 93–205, approved December 28, 1973, 

87 Stat. 884). Additional policy (64 FR 607277, November 8, 1999) has clarified 

that harm may include significant habitat modification where it actually kills or 

injures a listed species through impairment of essential behavior, such as 

nesting or reproduction.

 Inform Solutions

Ultimately, to advance renewable energy and conserve 

wildlife, workable, cost-effective strategies are needed that can 

reduce impacts of energy development on wildlife. This may 

include new strategies for wildlife or habitat management, or 

technological solutions to avoid, minimize, or mitigate harm. 

The USGS has provided decades of research supporting technical 

and operational solutions for hydroelectric facilities for fish 

passage and management of aquatic habitat. For the wind energy 

sector, research to inform solutions includes turbine curtailment 

and deterrent strategies for facilities, and preconstruction 

siting decision tools to minimize exposure of wildlife to risks. 

Additionally, data and models for estimating range-wide 

risks by identifying wildlife migration corridors, other habitat 

associations, and population trends may be useful for facility 

siting decisions.

Forecasting Golden Eagle Fatalities

Eagles are at the forefront of concerns about renewable 

energy in part because it is a Federal offense under the Bald and 

Golden Eagle Protection Act (16 USC 668-668c) to take an eagle 

without a permit. The U.S. Fish and Wildlife Service recently 

developed an eagle-permit process as an incentive-based 

mechanism that provides overall conservation benefits to eagles 

and, in return, grants developers and other potential permittees a 

degree of legal and financial certainty. The USGS has supported 

implementation of this process by developing a method to 

provide a pre-construction forecast of golden eagle fatalities at 

proposed wind energy facilities (New and others, 2015). This 

is important information because the geographic location, local 

topographical features, and other factors potentially play a role 

in the number of eagle fatalities. The forecast allows regulators 

to work with developers to design a wind energy facility that 

minimizes eagle mortality. It also is used for determining the 

amount of compensatory mitigation needed as a result of 

facility operations. 

Acquiring Fatality Information for Rare Species

Wildlife managers often are concerned about collisions 

of rare species with turbines because this additional mortality 

may change the viability of a rare population. Fatality rates of 

rare species can be difficult to estimate simply because none or 

few may ever be found during periodic searches. Observing no 

fatalities could mean that no animals were killed, or perhaps 

some were killed but all carcasses were scavenged or missed 

in searches. The USGS, in partnership with the U.S. Fish and 

Wildlife Service, has developed an approach for estimating 

mortality even when few or no fatalities are observed (fig. 2; 

Dalthrop and others, 2014). The tool helps managers interpret 

evidence that the permitted level of take1 has not been exceeded 

or whether adaptive management or compensatory mitigation 

is needed. This tool has been helpful in the development of 

habitat conservation plans for wind projects, particularly in the 

Midwestern United States. 

Figure 2. The tool by Dalthorp and others, 2014 helps industry 

operators optimize use of resources when conducting surveys 

for wildlife carcasses beneath wind turbines. Graphs like this are 

generated by the tool and help operators make choices about survey 

design to achieve a desired detection rate for a rare species.
0

50,000

2004 2005 2006 2007 2008 2009

Year

Gigawatt hours

2010 2011 2012 2013 2014

100,000

150,000

200,000

250,000

Solar

Wind

EXPLANATION

Figure 3. United States renewable electricity generation for 

grid-connected wind and solar power. (Source: U.S. Energy 

Information Agency.)

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

http://dx.doi.org/10.3133/fs20163067

Author: 

Mona Khalil

For more information:

USGS Energy and Wildlife Program

https://www2.usgs.gov/ecosystems/energy_wildlife

1-800-ASK-USGS (1-888-275-8747)

Photograph credits: Hoary bat, ©Merlin Tuttle.org

All other images from USGS.

Publishing support provided by the U.S. Geological Survey, 

Science Publishing Network, Tacoma Publishing Service Center

Design: William Gibbs

Growth of Wind and Solar Sectors

Renewable energy is generated using technologies 

that convert the natural power of wind, sun (solar), 

plants (biomass), Earth’s heat (geothermal), and 

water (hydro, tidal, and hydrokinetic) into electricity. 

In the past decade, the scale of wind and solar energy 

development has expanded across the United States 

(fig. 3). Wind turbines now contribute to power grids 

in most states, and the number of utility-scale solarenergy projects is growing rapidly in the Southwest 

as well as in the South Atlantic Region. A significant 

number of large projects occur on undeveloped 

public lands, and new projects are anticipated to 

occur at an increasing rate, which can create new 

stress on wildlife. Because new projects often occur 

in or near wildlife habitat, ecological science plays 

an important role in helping to guide project siting 

and operational decisions.

Research Studies

Boyles, J.G., Cryan, P.M., McCracken, G.F., and Kunz, T.H., 

2011, Economic importance of bats in agriculture: Science, 

v. 332, no. 6025, p. 41-42, doi:10.1126/science.1201366.

Cryan, P.M., Gorresen, P.M., Hein, C.D., Schirmacher, M.R., 

Diehl, R.H., Huso, M.M., Hayman, D.T.S., Fricker, P.D., 

Bonaccorso, F.J., Johnston, D.H., Heist, Kevin, and Dalton, 

D.C., 2014, Behaviors of bats at wind turbines: Proceedings 

of the National Academy of Sciences, v. 111, no. 42, 

p. 15,126–15,131, doi:10.1073/pnas.1406672111.

Dalthorp, Dan, Huso, Manuela, Dail, David, and Kenyon, 

Jessica, 2014, Evidence of absence software user guide: U.S. 

Geological Survey Data Series 881, 34 p., doi:10.3133/ds881.

Gorresen, P.M., Cryan, P.M., Dalton, D.C., Wolf, S., Johnson, 

J.A., Todd, C.M., and Bonaccorso, F.J., 2015, Dim ultraviolet 

light as a means of deterring activity by the Hawaiian hoary 

bat Lasiurus cinereus semotus: Endangered Species Research, 

v. 28, no. 3, p. 249–257, doi:10.3354/esr00694.

Huso, Manuela, Som, Nicholas, and Ladd, Lew, 2012, Fatality 

estimator user’s guide (ver. 1.1, December 2015): U.S. 

Geological Survey Data Series 729, 22 p., doi.10.3133/ds729.

New, L., Bjerre, E., Millsap, B., Otto, M.C., and Runge, M.C., 

2015, A collision risk model to predict avian fatalities at 

wind facilities—An example using golden eagles, Aquila 

chrysaetos: PLOS ONE, v. 10, no. 7, e0130978, doi:10.1371/

journal.pone.0130978.