The greater sage-grouse (Centrocercus urophasianus) is the largest grouse species in North America. It is known for its elaborate mating rituals where males congregate on leks and inflate air sacs in their chests to make popping sounds. Sage-grouse depend on sagebrush for food and shelter, and have declined in numbers and range over the past century due to habitat loss and fragmentation. Understanding the current status of greater sage-grouse populations is important for conservation efforts.
Where do greater sage-grouse live?
Greater sage-grouse historically occupied sagebrush habitats across 13 western U.S. states and 3 Canadian provinces. Their range covered over 1.2 million square kilometers. Today, sage-grouse occupy about 56% of their historical range, reduced to about 668,000 square kilometers across 11 states in the western U.S. and 2 provinces in Canada (see Table 1). The largest populations are found in Wyoming, Idaho, Nevada, Oregon and Montana.
State/Province | Historical Range (km2) | Current Range (km2) |
---|---|---|
Wyoming | 259900 | 188900 |
Idaho | 256600 | 141000 |
Nevada | 242600 | 115600 |
Oregon | 175600 | 95600 |
Montana | 168900 | 100000 |
Utah | 151900 | 37800 |
Colorado | 115800 | 29400 |
Washington | 97600 | 19300 |
California | 40500 | 8300 |
North Dakota | 8700 | 3600 |
South Dakota | 2100 | 100 |
Alberta | 83800 | 72800 |
Saskatchewan | 1900 | 300 |
Sage-grouse have been extirpated from the periphery of their range, including areas in Arizona, Nebraska, Oklahoma and New Mexico in the United States and southern British Columbia in Canada.
How many greater sage-grouse remain?
Current total population estimates for greater sage-grouse range between 200,000 to 500,000 individuals. More precise estimates are difficult due to the vast sagebrush habitats they occupy and fluctuations in numbers each year. The 2015 Greater Sage-Grouse Umbrella Conservation Strategy put the rangewide breeding population between 200,000 to 300,000 birds.
Population trends vary in different parts of their range. Wyoming likely has the most sage-grouse with an estimated population size between 37,000 to 129,000 breeding adults. Populations in Colorado, Utah, California and the Dakotas have declined to only a few hundred or thousand birds in each state. Overall, populations have declined by 45-80% from historical numbers prior to European settlement of the western states.
Why are greater sage-grouse populations declining?
Loss and fragmentation of sagebrush habitats are the main causes of greater sage-grouse decline. Since European settlement, sagebrush areas have been reduced by an estimated 50% through conversion to cropland, urbanization, resource extraction and incompatible grazing practices. Additional threats come from herbicide treatments, roads, fences, powerlines, and invasive plants invading sagebrush areas.
Energy development for oil, gas and wind energy infrastructure has also contributed to habitat declines, fragmentation and direct mortality. The noise from drilling rigs and traffic can disrupt breeding behaviours on leks. Sage-grouse avoid tall structures such as powerlines and wind turbines, resulting in functional habitat loss.
Other factors in sage-grouse declines include overgrazing by livestock, mortalities from vehicle strikes, West Nile virus, and predation on nests and juveniles. Hunting contributed to early declines but is now closely regulated throughout their range.
How is the greater sage-grouse population monitored?
State and provincial wildlife agencies monitor sage-grouse populations through lek counts every spring. A lek is an area where male sage-grouse congregate and perform courtship displays to attract females for breeding. Monitoring lek attendance of males provides an index of reproductive activity and population trends.
Lek counts are conducted in known lek areas from early March to May each year. Ground or aerial surveys record the peak number of male sage-grouse observed over multiple visits to each lek site. The maximum male count at each lek is summed across all leks to estimate changes in the overall breeding population.
There are challenges in interpreting lek count data. Poor weather can impact lek attendance on survey dates. The vast sagebrush habitats make it difficult to find all existing lek sites. Smaller satellite leks may not be monitored. However, lek counts remain the primary method for monitoring sage-grouse numbers across their range.
What conservation efforts are underway?
Many federal, state and provincial agencies have conservation plans and efforts to protect sage-grouse populations. These include:
- Habitat restoration programs to improve sagebrush lands
- Working with landowners to adopt sage-grouse friendly practices
- Protecting key habitat areas from development
- Reducing other threats and disturbances in priority habitats
- Monitoring populations and habitats
- Regulating hunting seasons and limits
- Raising awareness of sage-grouse conservation
In 2015, the U.S. Fish and Wildlife Service determined that listing the greater sage-grouse under the Endangered Species Act was “not warranted”. This decision was based on conservation efforts and plans developed by states, landowners and federal agencies through the collaborative Sage-Grouse Task Force.
What does the future look like for greater sage-grouse?
Greater sage-grouse remain dependent on large expanses of sagebrush habitat across western North America. Balancing conservation needs with economic development and recreational activities on public lands will continue to be a challenge.
Ongoing monitoring is critical to track populations and habitat changes over time. Conservation plans must be implemented, refined and expanded to protect key wintering and breeding areas. Reducing habitat fragmentation and disturbances from human infrastructure remains a priority.
Climate change adds uncertainty, with potential impacts on fire regimes and vegetation changes in sagebrush ecosystems. Maintaining connectivity of habitats will help sage-grouse adapt to a changing environment.
While many threats remain, collaborative conservation efforts across agencies, landowners and other stakeholders provide hope. With continued focus and commitment, sagebrush lands can be stewarded to support sustainable greater sage-grouse populations into the future.
Conclusion
Greater sage-grouse remain a species of conservation concern despite collaborative efforts to protect populations and habitats. They now occupy only 56% of their historical range in western North America. Total population size is estimated between 200,000 to 500,000 birds, down from over a million historically. The loss and fragmentation of sagebrush habitats are the main threats driving declines.
Conservation plans and partnerships among agencies, landowners and other stakeholders are working to restore and connect priority habitats. Still, sage-grouse face ongoing challenges from energy development, climate change and other factors. Continued focus on implementing conservation actions, monitoring populations, and managing sagebrush lands sustainably will be key to securing the future for greater sage-grouse.