Competition: it's a fundamental concept in ecology and conservation along with every other social interaction in the natural and human world. Individuals compete with one another for mates; species compete with one another for territories to monopolize resources; priorities compete with one another for policies; social and environmental justice competes with economic wants and needs to shape our shared ethics and values. YERC is currently helping resolve what is becoming a national-level conflict borne of competition for a windswept corner of the Greater Yellowstone Ecosystem in southeastern Wyoming.
The Sage Grouse is the largest grouse in North America, and is known for using distinct breeding areas, called “leks,” where males inflate air sacs in their neck and chests and strut their stuff to impress females watching from the dense sagebrush surrounding the lek. The species was considered a candidate for Endangered Species Act protection until 2015, when managers reversed the decision following successful local-based conservation efforts and science-based policy decisions. YERC participated in making that science available to conservationists and policy-makers.
On the Thunder Basin National Grassland—a jigsaw puzzle of federal, state, and private land tucked between the Bighorn Mountains to the west and the Black Hills to the east—rumbling from competition over habitat conservation and economic development echoes that of the region's namesake prairie storms.
The Thunder Basin National Grassland in southeastern Wyoming, roughly one million acres of prairie administered by the U.S. Forest Service. It is home to one of the southernmost populations of greater sage-grouse as well as oil and gas development, coal mines, wind farms, and a ranching industry.
One of twenty national grasslands administered by the U.S. Forest Service, Thunder Basin is home to the greater sage-grouse—recently a high profile candidate for U.S. Endangered Species Act protection—as well as the extraction and production of energy resources including coal, oil and gas, and wind. The roughly one million acre grassland is at the southern fringe of the threatened species' range—threatened by habitat loss associated with energy development, among other things—where the population is likely living at its environmental limit.
In collaboration with other researchers and managers working on the ground, we used
sage-grouse spatial data collected from radio telemetry and visual observations to
investigate the environmental and human-caused factors affecting how the chicken-sized
bird uses its habitat.
First, we thought of all the possible factors, or "covariates," that might affect habitat selection: minimum and maximum temperatures, percent sagebrush cover, distance from natural gas wells, things like that. Then we collected spatial data for all of these covariates—basically maps of Thunder Basin where every point has a value for its model-based temperature estimates, its photo-measured sagebrush coverage, its GPS- calculated distance from the nearest gas well, and every other covariate. We then compared all of the values for the points that the sage-grouse used to random points that would have been available to the sage-grouse, revealing statistical relationships showing how these covariates affect the bird's habitat selection. To account for seasonal and interannual variation, we subdivided the data and replicated the analysis for summer and breeding seasons as well as years when the sage-grouse population increased and years when it decreased.
Univariate: Our analysis looked at various factors, or “covariates,” affecting how sage-grouse use their environment, revealing certain conditions driving an increased or decreased probability of selection. These thresholds can help managers identify good sage-grouse habitat in the Thunder Basin National Grassland as well as other parts of the species range.
The results of these analyses—called resource selection probability function (RSPF) models—identified the most important covariates affecting sage-grouse habitat selection and particular threshold values delineating prefered conditions. They also produced "heat maps" of the Thunder Basin, combining all these individual covariates to identify areas of increased probability of sage-grouse selection across the landscape, providing a quick visual representation of the most important habitats for sage-grouse on the grassland. They can be immediately put to use planning conservation priorities as well as sustainable development.
RSPF: By determining the ideal conditions for sage-grouse under each covariate, then combining all of these covariates as they are distributed across the landscape, we can produce a comprehensive predictive model that identifies prime sage-grouse habitats in Thunder Basin. Such a “heat map” of the probability of a sage-grouse selecting a given area provides managers with an instant, easily understood assessment of how the birds use their environment, and how managers should anticipate their needs in promoting conservation as well as economic development.
While Thunder Basin has been a successful project, providing applicable information as
well as proving the utility of the RSPF analyses, even greater potential awaits our sage-
grouse data from the Upper Green River Basin. We are just now embarking on a similar
analysis here, but with more data and the ability to produce models with predictive
powers extending beyond this immediate study area. This invaluable dataset spans
twelve years before, during, and after oil and gas development, making it a high
potential project to push forward adaptation and mitigation strategies that work.
Additional support for this analysis would enable the creation of additional covariate data products—mapping out power lines and marking the locations of poles where predatory hawks like to perch, for example. Mapping the distribution of sound (possible disturbance) is another. Support would also be used to increase the harddrive space needed to efficiently run analysis models simultaneously. And it would help us make sure the information is used in this part of the sage-grouse's range and beyond, through technical publications available to managers and other researchers as well as through popular media products accessible to policy-makers and the general public.
Endangered Species Act protection is a last resort measure, causing socio-economic repurcussions at a time when the species is already on the edge and when conservation measures may be too little, too late. It is better for the species and their environment and for regional communities and economies to avoid the ESA in the first place with healthy, sustainable populations. Indeed, in 2015 the U.S. Fish and Wildlife Service decided that ESA protection was no longer warranted for the greater sage-grouse, thanks in large part to local based conservation efforts and scientific findings provided by YERC and others. But just because a species on the fringe has avoided ESA protection, for now, doesn't mean that it is completely safe.
You can help conserve this species and its sagebrush environment by helping us continue our research here. Your support will help us to continue informing the successful, effective, science-based policy necessary to protect all interests in this High Plains region.