Stretching across the American West, the “Sagebrush Sea” is one of North America’s most iconic and imperiled landscapes. This vast ecosystem supports an array of wildlife and plants. Recent research from the United States Geological Survey underscores just how much is at stake and how quickly we need to act to save it.
A Landscape Under Pressure
The Sagebrush Sea is home to an estimated 350 at-risk species, from the well-known greater sage-grouse to lesser-known animals like the pygmy rabbit and sagebrush sparrow. Many of these species depend entirely on sagebrush to survive. Take the pygmy rabbit, a true sagebrush specialist. Today, it occupies only about 10% of its historic range, and its populations continue to decline across the West.
The broader picture is just as concerning. The Sagebrush Sea is now widely recognized as one of the most threatened biomes in North America. According to USGS, only 13.6% of intact core sagebrush habitat remains and more than 1.3 million acres are lost every year.
There are multiple reasons for the continuing decline in this landscape. The majority of the biome is experiencing a multi-year drought, which, in concert with an aggressive invasion of annual grasses and widespread grazing, alters vegetation patterns and large-scale natural processes (e.g., hydrologic cycles, fire) to which native wildlife are evolved. Concerningly, roughly one-fourth of public lands within the biome are now thought to be dominated by invasive plants such as cheatgrass.
In addition, most of the federally-controlled lands within the biome (over 40% administered by the Bureau of Land Management) are open to a variety of uses that can degrade and fragment habitat. For instance, 81% of all BLM lands are open to oil and gas leasing, 60% are open to livestock grazing and over 85% are open to mining.
A Science-Based Approach to Conserving and Restoring the Sagebrush Sea
Despite these challenges, USGS research offers a potential conservation roadmap. In a landmark 2022 report, USGS scientists mapped the Sagebrush Sea based on percent of sagebrush cover, percent of annual and perennial grass cover, and an index of human modification, and divided the biome into three categories:
- Core areas: The most intact, high-quality sagebrush habitat, representing 13.6% of the landscape.
- Growth opportunity areas: Degraded but still restorable landscapes, representing 34.4%.
- Other rangeland areas: Highly altered places where ecological restoration would be difficult, representing 51.9%.
This mapping supports a framework strategy known as “defend and grow the core.” The idea is simple, defend the remaining intact sagebrush strongholds (the “cores”) and grow the landscape by restoring areas with the best chance of recovery (the “growth opportunity areas”).
To test this hypothesis, researchers evaluated how the framework benefits wildlife and found that protecting healthy sagebrush strongholds provides broad benefits across multiple species. For instance, they looked at sage-grouse population trends from 1996–2021 and found populations were the most stable in the core areas. The same holds for other signature sagebrush songbirds, including the sagebrush sparrow, Brewer’s sparrow and sage thrasher.
In fact, they found that bird abundance was up to 10-fold higher in the core areas than in other rangeland areas. Further, roughly 78% of the total pygmy rabbit population occurs within the mapped core and growth opportunity areas of the Sagebrush Sea.
Together, these findings show that the conservation design is more than a map; it provides an effective tool for identifying the habitats where protection and restoration investments are most likely to support a variety of native wildlife.
Even in the face of climate change, this strategy holds up. One 2024 study found that while much of the Sagebrush Sea may degrade under changing climate conditions, most core areas are expected to remain relatively stable. That makes the cores even more important, both as key areas for wildlife today and as anchors for the future.
The researchers also analyzed recent conservation efforts to evaluate alignment with core areas, along with the pace and scale of this work. They found recent conservation efforts have not kept up with the fast decline of the sagebrush ecosystem, and roughly 90% of recent conservation actions have occurred outside of core areas, even as losses continue within them. Increasing and targeting conservation investments in core and growth opportunity areas would improve return on investment and help shift the trajectory of this declining biome.
At the same time, this strategy is not a silver bullet. The conservation landscape design offers an important, science-based path forward for coarse-scale protection of the broader landscape, but it is just one piece of the conservation puzzle. The framework must be carried out with rigorous standards-based restoration practices and accountability to conservation outcomes.
Additionally, to truly reverse declining trends, we also need stronger species-specific protections that address the unique needs of wildlife such as Greater sage-grouse, pygmy rabbits and other sagebrush-dependent species.
The science is clear: we still have a chance to work toward conserving the Sagebrush Sea, but the window is closing. Researchers explicitly state that “business-as-usual won’t save the Sagebrush Sea.” With the right focus on defending what remains and restoring what we can using best restoration practices, we can begin to chart a different future for this iconic western biome and the wildlife that call it home.
To learn more about Defenders of Wildlife’s work in the Sagebrush Sea, explore our StoryMap and stay tuned for forthcoming blog posts that will take a deeper look at key issues and policy developments affecting the landscape and its wildlife.
To learn more about the science behind the conservation design, see this collection of recent studies published in Rangeland Ecology & Management.
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