Printer on recycled paper U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005-3091

July 2005

USGS—Providing Scientific Understanding of the 

Sagebrush Biome

Early explorers wrote about the vast 

sea of sagebrush that stretched in front 

of them. Today, the consequences of 

land-use practices, invasion by exotic 

plants, and altered disturbance regimes 

have touched virtually all of these seemingly endless expanses. Increasing human 

populations in the western United States, 

the infrastructure necessary to support 

these populations, and a growing demand 

for natural resources exert a large influence. Changes within the biome have 

resulted in its designation as one of the 

most endangered ecosystems in North 

America.

The relatively simple structure of 

the sagebrush biome masks a complex 

ecosystem. Historical events, plants, animals, climate, weather, soils, elevation, 

and hydrology interact in the biome’s 

response to disturbance or land use. Providing the unbiased scientific understanding needed by agencies responsible for 

stewardship of this biome is a tremendous challenge.

The most comprehensive documentation of range-wide population trends, 

habitat conditions, and potential threats 

to the sagebrush biome is found in a 

recent report—Range-wide Conservation Assessment for Greater Sage-grouse 

and Sagebrush Habitats1. This assessment, sponsored by the Western Association of Fish and Wildlife Agencies, was 

written by a team of scientists from the 

U.S. Geological Survey (USGS), Idaho 

Department of Fish and Game, Washington Department of Fish and Wildlife, 

and others. Aptly named, the assessment 

provides a large-scale, 

ecological perspective 

of the sagebrush biome. 

The information helps 

us understand the condition and dynamics of the 

biome, can guide conservation management 

activities, and can focus 

future research efforts. The 

greater sage-grouse is the 

focus of the report because 

it is a sagebrush-obligate, 

dependent on sagebrush 

for all or part of its life 

cycle, and as such, is 

assumed to function as an 

indicator of the condition 

and trend of the biome. 

Many questions about 

sage grouse and habitats 

were not answered in the 

assessment, nor did the 

report assess conditions of other sagebrush- obligate species. In addition, the 

daunting challenges of stabilizing sage 

grouse populations, improving or restoring habitats, and implementing appropriate monitoring strategies remain.

Ecological Science Framework 

and Research Examples

The complex natural resource and 

societal issues in the sagebrush biome 

require that federal and state agencies, 

universities, and nongovernmental organizations collaborate if we are to succeed 

in conserving the sagebrush biome. The 

science framework presented here is a 

basic conceptual structure for helping 

to understand sagebrush ecosystems. 

The goal underlying the framework is to 

integrate emerging scientific understanding into future management in order to 

restore and maintain long-term ecosystem 

health and ecological integrity, emphasize 

adaptive management over the long term, 

provide consistent management direction 

over broad spatial and temporal scales, 

and restore and maintain habitats for 

plant and animal species.

As we strive to achieve this goal, 

ecological research needs to be designed 

and accomplished to 1. synthesize and 

build on existing information, 2. delineate 

and interpret regional indicators of habitat 

conditions and wildlife population trends, 

3. identify the effects of land use on 

habitats and wildlife, 4. develop restoration strategies, and 5. implement feedback 

1

 Available at http://sagemap.wr.usgs.gov/.

Quick Facts about Sagebrush Biome

m About 480,000 km2 (120 million acres) across 14 

western states and 3 Canadian provinces

m Largest semi-arid ecosystem in the West

m Mostly situated between Sierra Nevada and Cascade 

Mountain ranges and the Rocky Mountains

m Typically cold, wet winters and hot, dry summers

m In native condition, botanically characterized by 

shrubs interspersed with grasses and forbs

m Sagebrush often dominates where snow and rainfall 

exceed 18 cm (7 in) per year

m More than 70 percent public ownership; public land 

primarily managed by the Department of the Interior

m Major land uses include agriculture, mining, energy 

development, livestock grazing, and urbanization

m Primary stressors include the land uses listed above 

plus invasion of exotic plants, competition for water, 

soil erosion, altered fire cycles, and wildlife diseases

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in an objective evaluation of management 

actions. Specifically we are integrating our 

science disciplines to focus on four areas: 

n Understand the effects of habitat 

change on sagebrush-obligate species

n Develop cost-effective methods 

for restoring functioning sagebrush 

ecosystems 

n Implement quantitative monitoring strategies as part of an adaptive 

program to detect changes resulting 

from management actions or habitat 

disturbances

n Manage spatial and nonspatial data 

to provide the information needed 

by researchers, resource specialists, 

managers, and the public

The USGS is working with other 

federal, state, university, and nongovernmental partners to conduct research that 

will improve our understanding of ecological conditions in the sagebrush biome and 

to provide information needed to manage 

and restore sagebrush ecosystems and the 

species that depend on them. The following 

examples demonstrate the capabilities of 

USGS science to inform management decisions in the sagebrush biome. 

Effects of Habitat Change on 

Sagebrush-Obligate Species

Environmental Correlates of Greater Sagegrouse Distribution and Population Trends

Patterns of distribution of greater 

sage-grouse populations and sagebrush 

habitats are well documented, but the 

underlying causes for population trends or 

habitat changes are poorly understood. To 

address this critical information need, the 

USGS and state and university partners 

are correlating long-term trends in greater 

sage-grouse populations with habitat 

changes. We also are 

describing the effects 

of roads, power lines, 

and other infrastructures on greater 

sage-grouse populations, and testing the 

assumption that the 

greater sage-grouse 

is an appropriate 

umbrella species for 

managing sagebrush 

habitats.

National Oil and Gas Assessments 

Oil and natural gas resources have 

been developed in the sagebrush biome 

for over a century, but recently, exploration and development have increased 

dramatically because of high demand 

for energy resources. A requirement for 

predicting ecological consequences of 

development is knowledge of where 

developments have and will occur. We 

conducted energy resource assessments 

of basins with petroleum and coalbedmethane-production potential throughout 

the Rocky Mountain Region and used 

this assessment to describe areas of current and potential future developments. 

We also are conducting an ecological

Who is the USGS?

The USGS serves as an independent research agency that collects, monitors, and analyzes data 

to provide scientific understanding 

about natural resource conditions, 

issues, and problems. It has no 

regulatory or management mandate but serves to provide impartial science. As a federal science 

agency, the USGS has the added 

responsibility and capability to 

conduct studies at multiple spatial 

(local, regional, and national) and 

temporal (days to decades) scales. 

Furthermore, the diversity of scientific expertise available within 

the agency, including biologists, 

hydrologists, geographers, and 

geologists, enables the USGS to 

carry out large-scale, multi-disciplinary investigations. Some 

of these investigations integrate 

information to make inferences 

about phenomena that are too 

broad to be explained by single 

scientific disciplines.

Wildlife Sentinels in the Sagebrush Biome

Warnings began appearing over a quarter of a century ago about loss of native 

sagebrush habitats and the consequences for wildlife. Greater sage-grouse (Centrocercus urophasianus), Gunnison sage-grouse (Centrocercus minimus), Brewer’s sparrow (Spizella breweri), and pygmy rabbit (Brachylagus idahoensis) all rely heavily 

on sagebrush habitat, and are only some of the wildlife impacted by changes in the 

sagebrush biome. The range of greater sage-grouse today is approximately 56 percent 

of its historical distribution, and abundance is greatly reduced from historic levels. 

Gunnison sage-grouse, a close western relative of the greater sage-grouse, occupies 

only 11 percent of its historic range, and the species is a candidate for listing under 

the Endangered Species Act. The number of Brewer’s sparrows has declined on 

breeding bird surveys conducted over the past 30 years. The smallest rabbit in North 

America, the pygmy rabbit, is classified by the federal government as a species of 

concern because of its specialized habitat requirements and evidence of declining 

populations, and one distinct population in the Columbia Basin is listed as endangered under the Endangered Species Act.

© Mark Chappell © Mark Chappell © Keith Lazelle
analysis of one basin, the Wyoming Basin, to estimate the 

amount of habitat influenced by activities associated with energy 

developments. In addition, we are using geographic information 

systems and remote sensing to quantify the indirect effects that 

potentially result from increased presence of exotic plants and 

from additional predators that affect wildlife populations.

West Nile Virus in Greater Sage-grouse

West Nile virus is a known cause of death for wild greater 

sage-grouse, and laboratory experiments show that this species is 

highly susceptible to the virus. Our research associated with this 

virus is designed to develop a disease monitoring and research 

strategy. In addition to evaluating the prevalence of exposure 

to West Nile virus and other avian pathogens in greater sagegrouse, we are sampling other vertebrates in sagebrush habitats 

to determine if they are affected by the virus and what role they 

may play in disease transmission. Early laboratory studies indicate that chukar partridge may serve as an amplifying host for 

West Nile virus and may be a useful sentinel for the virus.

Birds of a Different Feather

Genetic analyses have led to a host of discoveries associated with sage grouse, including recognition of the Gunnison 

sage-grouse as a distinct species, confirmation of geographically and genetically isolated populations of both Gunnison and 

greater sage-grouse, and understanding of gene flow, population 

connectivity, and gene pool diversity. We are continuing with 

these types of studies to help determine the effective size of 

populations and, inverse to this, the minimum size of a viable 

population. We also are testing if we can effectively monitor 

sage grouse using an individual bird’s unique DNA and thereby 

estimate population abundance, survival, and movements. Information from such gene-based research can be used 

to develop comprehensive management strategies 

that take into account the “genetic landscape” of each 

species, thereby preserving genetic distinctiveness in 

some populations or increasing genetic diversity in 

others.

Restoration of Functioning Sagebrush 

Ecosystems

Restoration of Sagebrush Habitats in the Great Basin 

and Columbia Plateau Ecoregions

Restoring sagebrush habitats in the sagebrush 

biome is a tremendous challenge. Low precipitation, 

fragile soils, competition from exotic plants, and technological difficulties are barriers to success. Logistics and limited funding restrict the number of areas 

in which managers can attempt restoration. We are 

developing models using spatial data to assist in prioritizing regions in which success is most likely and 

of greatest benefit to greater sage-grouse and other 

wildlife. The models combine information about soils, 

precipitation, and other environmental features across 

the entire sagebrush biome, as well as information 

about locations of sage grouse and sagebrush habitats. 

Percent

sagebrush

habitat

1–25

26–50

51–75

76–100

0 87.5 175 350 525 700

Kilometers

!

"

#

$

3AGEBRUSH"IOME

&IRES

/ILANDGAS

0OWERLINES

A. Sagebrush biome (shades of 

green) based on historic range 

of greater sage-grouse.

B–D. Examples of infractructures and disturbances in 

sagebrush biome.
Coordinated Intermountain Restoration Program 

The Coordinated Intermountain Restoration Program provides research and technical assistance needed to understand 

the effects of disturbance and invasive plants on the structure 

and function of Wyoming big sagebrush ecosystems and how to 

restore native plants where cheatgrass dominates. The program 

promotes the understanding of disturbance dynamics but, at a 

more applied level, it also provides guidance with selecting plant 

materials, site preparation techniques, methods of weed control, 

seeding equipment, management methods, and monitoring techniques for restoration projects. Additionally it provides research 

and technical assistance associated with fuels management to 

reduce the impacts of wildfires on semi-arid rangelands where 

exotic annual grasses provide the fuel. This is a major collaboration, involving the USGS, the Bureau of Land Management 

(BLM), universities, and many other partners.

Monitoring as Part of Adaptive Management 

Evaluation of Fire Effects and Fire-Surrogate Treatments in the 

Sagebrush Biome 

Federal agencies use a variety of management methods on 

western rangelands to alleviate the potential for fire, restore 

native plant communities, and create habitat for wildlife. We and 

other collaborators are studying these treatments (prescribed fire, 

herbicides, cutting and removal of woody species, and brush 

beating) to determine the conditions under which sagebrush 

communities recover on their own following treatment versus 

conditions that require active restoration. The program specifically considers how treatments influence the primary ecosystem 

processes that contribute to recovery. This information is important for understanding the characteristics of these systems that 

facilitate or resist the spread of invasive plants or the encroachment of pinyon-juniper woodlands. This research also will 

determine the habitat components that influence the distribution 

and abundance of wildlife species. 

Evaluation of Habitat Treatments 

Recovery of greater sage-grouse and other sagebrush-obligate 

species depends on preserving and restoring sagebrush habitats 

at landscape scales. Prescribed fire, and mechanical and chemical treatment of vegetation contribute to the loss and fragmentation of sagebrush communities but, if used appropriately, these 

techniques may aid restoration. Furthermore, the National Fire 

Plan mandates reductions in hazardous fuels to decrease the 

likelihood of large rangeland fires and to restore these areas 

to historic structure and function. We are evaluating changes 

in vegetation and in greater sage-grouse food items after fuels 

management treatments that were carried out at sites in Idaho, 

Nevada, and Wyoming between 1997 and 2004. We also are 

developing and testing assessment protocols for determining the 

extent and dominance of cheatgrass, a major contributor to wildfire, in the sagebrush biome. This research will help determine 

which lands require restoration and which are resilient enough to 

recover on their own after the treatments.

Information Management and Technical Support

Integration of Sound Science and Adaptive Strategies in Sage 

Grouse Conservation Planning 

We continuously strive to bridge the gap between the information decision makers require and the information generated 

through research. Demonstrating this, the USGS is part of a 

particularly effective collaboration with a local working group in 

Nevada and eastern California (the Bi-State Work Group), where 

we helped develop a conservation plan for greater sage-grouse. 

Ongoing work with this group and other partners includes development of models that integrate policy and economic choices, 

sage grouse habitat maps, and plans for monitoring sage grouse 

populations.

Role of Information Portals and Data Management

Huge amounts of biological information are compiled about 

the sagebrush biome every year. Effective access to this information by management agencies, policy makers, the general public, 

and researchers is crucial. In 2001, the BLM and the USGS 

launched a web portal called SAGEMAP, designed to deliver 

spatial data and other information about sagebrush ecosystems 

to researchers and managers in a concise and easily searchable 

format. Several other information portals provide biological 

and spatial data for the sagebrush biome (see box), all managed 

under the auspices of the National Biological Information Infrastructure. One aspect of the Great Basin Information Project is a 

science locator 

system, aimed at 

providing brief 

descriptions 

of all research 

in the Great 

Basin, cross 

referenced to 

locations where 

the research 

occurs and to 

the investigators 

involved. 

Contact:

USGS Forest and Rangeland Ecosystem Science Center

777 NW 9th St., Suite 400, Corvallis, OR 97330

E-mail: fresc_outreach@usgs.gov

Telephone: 541-750-1030

Web Portals for the Sagebrush Biome

m SAGEMAP http://sagemap.wr.usgs.gov/

m Great Basin Information Project

http://greatbasin.nbii.gov/

includes links to Science Locator

m Wildlife Disease Information Node 

http://wildlifedisease.nbii.gov/

m Mountain Prairie Information Node 

http://nrin.nbii.gov/

USGS Science Centers Involved in Research 

Forest and Rangeland Ecosystem Science Center 

http://fresc.usgs.gov/ • 541-750-1030

Fort Collins Science Center

http://www.fort.usgs.gov/ • 970-226-9100

National Wildlife Health Center

http://www.nwhc.usgs.gov/ • 608-270-2400

Western Ecological Research Center

http://www.werc.usgs.gov/ • 916- 278-9485

Southwest Biological Science Center

http://sbsc.wr.usgs.gov/ • 928-556-7094