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Restoring the Sagebrush Sea: The Warner Mountains Project

For eight years, the Warner Mountains in southeastern Oregon served as a laboratory for university scientists studying the effects of strategic, large-scale conifer removal on sage grouse. This page compiles the studies, interviews, videos, and other products produced from this first-of-its-kind, long-term research effort.

Background: The rugged and remote Warner Mountains run from northern California into southeastern Oregon. Like many regions in the West, the Warners are comprised of public and private lands, and grazing plays an important role in the economies of the small towns that dot the landscape. Unfortunately, decades of woody plant encroachment had degraded much of this landscape, pushing out sagebrush-dependent wildlife, reducing livestock forage, and depleting precious water supplies.

In 2011, the USDA-NRCS’s Sage Grouse Initiative (SGI) partnered with the Bureau of Land

Map of study area in the Warner Mountains of Oregon. Credit: Andrew Olsen.

Management (BLM) and local landowners to begin a large-scale conifer removal project in the southeast Oregon portion of the Warner range. Additionally, the partners invited university scientists to study how sage grouse responded to the conifer removal treatments.

Over the next eight years, the partners strategically removed conifer trees on more than 100,000 acres of this landscape while leaving trees in place on an 82,000-acre “control” portion of the area.

Learn more about this project, the research it produced, and the stories of the people involved below.

Restoring the Sagebrush Sea details the successful outcomes of tree removal in the Warner Mountains for sage grouse and local ranchers. Click on the image above or here to learn how this work is informing other projects throughout the American West.

Explore this awesome storymap produced by NRCS Oregon that tells the Warner Mountains story!

Peer-reviewed science

• Title: Reversing Tree Encroachment Increases Usable Space for Sage-Grouse during the Breeding Season
• Published: The Wildlife Society Bulletin, September 2021
• Research Summary: Habitat preferred by sage grouse increased six-fold following conifer removal

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• Title: Reversing tree expansion in sagebrush steppe yields population-level benefit for imperiled grouse 
• Published: Ecosphere, June 2021
• Research Summary: Sage grouse population growth rates were 12% higher in the treated landscape versus the untreated landscape.

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• Title: Monitoring pinyon-juniper cover and aboveground biomass across the Great Basin
• Published: Environmental Research Letters, February 2020
• Research Summary: In the Great Basin, 1.1 million acres of rangelands have transitioned to pinyon-juniper forests (>10% canopy cover) at a rate of 0.46% per year since 2000.

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• Title: Restoring Sage-grouse nesting habitat through removal of early successional conifer
• Published: Restoration Ecology, May 2017
• Research Summary: Increased conifer cover in sagebrush ecosystems reduces habitat for nesting sage grouse, but conifer removal can restore nesting habitat suitability.

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• Title: Better living through conifer removal: A demographic analysis of sage-grouse vital rates
• Published: PLOS One, March 2017
• Research Summary: Where juniper was removed, female sage grouse annual survival increased by 6.6% and the nest survival rate increased by 18.8% each year.

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• Title: Short-Term Response of Sage-Grouse Nesting to Conifer Removal in the Northern Great Basin
• Published: Rangeland Ecology & Management, January 2017
• Research Summary: Within four years of conifer removal, 29% of marked sage grouse hens nested in restored habitats.

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• Title: Bird Responses to Removal of Western Juniper in Sagebrush-Steppe
• Published: Rangeland Ecology & Management, January 2017
• Research Summary: Abundances of sagebrush songbirds increased following conifer removal conducted primarily to benefit sage grouse.

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• Title: Effects of Conifer Expansion on Greater Sage-Grouse Nesting Habitat Selection
• Published: The Journal of Wildlife Management, October 2016
• Research Summary: Sage grouse hens avoided nesting where conifer cover exceeded 3% within 800m of their nests.

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• Title: Saving sage-grouse from the trees: A proactive solution to reducing a key threat to a candidate species
• Published: Biological Conservation, November 2013
• Research Summary: No sage grouse leks remained active with more than 4% tree cover in surrounding area.

SGI Posts and Interviews

• Restoring wide-open sagebrush habitat in southern Oregon benefits birds and ranchers
• New Research Finds That Sage Grouse Prefer Nesting In Conifer-Free Landscapes
• Conifer Removal Boosts Sage Grouse Success
• Sagebrush Songbirds Benefit from Sage Grouse Habitat Restoration
• When Trees Are Cut, Grasses & Shrubs Return
• Sage Grouse Population Increases When Western Juniper Pushed Back
• Saving Sage Grouse from the Trees: New Study Shows Benefits of Targeted Tree Removal to Declining Birds
• Sage Grouse Populations Grow When Conifers Are Removed

Farmers.gov blog post about rancher John O’Keeffe’s experience partnering on this project

>>Read more posts and research about the effects conifers have on sagebrush range and the benefits of removing them here.<<