Spatial scale selection for informing species (greater sage-grouse) conservation in a changing landscape.
We demonstrate the application of a scale selection approach that jointly estimates the scale of effect and the effect of sagebrush cover on trends in population size using counts from 584 sage-grouse leks in southwestern Wyoming (2003–2019) and annual estimates of sagebrush cover from a remote sensing product. From this approach, we estimated a positive effect of mean sagebrush cover with a 95% probability that the scale of effect occurred within 5.02 km of leks. In an average year, we found that lower levels of sagebrush cover within these estimated scales could support increasing trends in sage-grouse population size when populations were small, but higher levels of sagebrush cover were needed to sustain growing populations when populations were larger. With standardized monitoring and annual estimates of vegetation from remote sensing, this scale selection approach can be applied to identify relevant scales for other populations, species, and biological responses such as demography and movement.
We modeled seasonal habitat use by female greater sage-grouse in the Trout Creek Mountains of Oregon and Nevada, USA, to identify landscape characteristics that influenced sage-grouse habitat selection and to create predictive surfaces of seasonal use 1 and 7 years postfire. We developed three resource selection function models using GPS location data from 2013 to 2019 for three biologically distinct seasons (breeding, n = 149 individuals: 8 March–12 June; summer, n = 140 individuals: 13 June–20 October; and winter, n = 94 individuals: 21 October–7 March). For all seasons, by the fourth or fifth year postfire, sage-grouse selected for unburned patches more than all other burn severity patches and the use of unburned areas in comparison with burned areas increased through time. During the breeding season, sage-grouse selected for low-sagebrush -dominated ecosystems and areas with low biomass (normalized difference vegetation index). During summer, sage-grouse selected for areas with higher annual and perennial grasses and forb cover, and areas that had higher biomass. During winter, sage-grouse selected for areas of intact sagebrush on less rugged terrain. For the winter and breeding season, there was a positive linear relationship between annual grasses and forb cover through time. Seven years postfire (2019), the area predicted to have a high probability of use in each seasonal range decreased (breeding: 16.4%; summer: 12.2%; and winter: 4.2%), while the area predicted to have low or low-medium probability of use increased (breeding: 14.5%; summer: 22.5%; and winter: 22.8%) when compared to the first year following the wildfire (2013). Our results demonstrated a 4- to 5-year time lag before female sage-grouse adapted to a disturbed landscape began avoiding burned areas more than intact, unburned habitats. This mismatch in ecological response may imply declines in habitat availability for sage-grouse and may destabilize population vital rates. Spatially explicit models can aid in identifying priority areas for restoration efforts and conservation actions to mitigate the impacts of future disturbances.
Relationship of greater sage-grouse to natural and assisted recovery of key vegetation types following wildfire
We measured the presence of greater sage-grouse (GRSG) scat and modeled the probability of GRSG presence (PrGRSG-scat) in relation to variation in plot-level and landscape-level predictors, and land treatments, in an intensive, repeat sampling from 2017 to 2020 of 113,000 ha area burned in 2015 in the Soda Megafire (Oregon and Idaho, U.S.A.). GRSG scat was present in less than 200 of more than 8,000 observations, as would be expected for a philopatric species (i.e. high fidelity to home site) returning to degraded habitat. PrGRSG-scat was positively associated with sagebrush presence at the plot level and was positively related to elevation, lower-angle slopes, and proximity to sagebrush seedling outplant islands. The statistical significance of relationships of PrGRSG-scat to restoration treatments was marginal at best, with the largest effect being a positive response of PrGRSG-scat to pre-emergent herbicide sprayed to reduce exotic annual grasses. More time may be required for restored sagebrush steppe to meet GRSG needs or for GRSG to “adopt” the restored vegetation. Moreover, whereas scat is a convenient and non-invasive method to monitor GRSG, its post-fire scarcity weakens the strength of statistical inference on GRSG recovery patterns and response to restoration.
We found the predicted positive relationship between mesic habitat availability and sage-grouse productivity, but annual precipitation explained additional variation in productivity even after accounting for mesic habitat availability. Hence, precipitation and drought may drive sage-grouse productivity via more than one mechanism acting on multiple demographic rates. Productivity was also limited by exotic annual grass invasion and conifer encroachment. Mesic habitat availability was a function of topographic relief, mean elevation, annual mean snow water equivalent, and winter temperatures, indicating that snowpack recharges the late summer mesic resources that support sage-grouse productivity. Management actions focused on maintaining and restoring mesic resources and drought resilient habitats, limiting the spread of exotic annual grasses, and reversing conifer encroachment should support future sage-grouse recruitment and help mitigate the effects of climate change.
In 2006, we initiated fuel reduction treatments (prescribed fire, mowing, and herbicide applications [tebuthiuron and imazapic]) in six Artemisia tridentata ssp. wyomingensis communities. We evaluated long-term effects of these fuel treatments on: (1) magnitude and longevity of fuel reduction; (2) Greater sage-grouse habitat characteristics; and (3) ecological resilience and resistance to invasive annual grasses. Responses were analyzed using repeated-measures linear mixed models. Response variables included plant biomass, cover, density and height, distances between perennial plants, and exposed soil cover. Prescribed fire produced the greatest reduction in woody fuel over time. Mowing initially reduced woody biomass, which recovered by year 10. Tebuthiuron did not significantly reduce woody biomass compared to controls. All woody fuel treatments reduced sagebrush cover to below 15% (recommended minimum for Greater Sage-grouse habitat), but only prescribed fire reduced cover to below controls. Median mowed sagebrush height remained above the recommended 30 cm. Cheatgrass (Bromus tectorum) cover increased to above the recommended maximum of 10% across all treatments and controls. Ecological resilience to woody fuel treatments was lowest with fire and greatest with mowing. Low resilience over the 10 posttreatment years was identified by: (1) poor perennial plant recovery posttreatment with sustained reductions in cover and density of some perennial plant species; (2) sustained reductions in lichen and moss cover; and (3) increases in cheatgrass cover. Although 10 years is insufficient to conclusively describe final ecological responses to fuel treatments, mowing woody fuels has the greatest potential to reduce woody fuel, minimize shrub mortality and soil disturbance, maintain lichens and mosses, and minimize long-term negative impacts on greater sage-grouse habitat. However, maintaining ecological resilience and resistance to invasion may be threatened by increases in cheatgrass cover, which are occurring regionally.
This “Sagebrush Conservation Strategy—Challenges to Sagebrush Conservation,” is an overview and assessment of the challenges facing land managers and landowners in conserving sagebrush ecosystems. This strategy is intended to provide guidance so that the unparalleled collaborative efforts to conserve the iconic greater sage-grouse (Centrocercus urophasianus) by State and Federal agencies, Tribes, academia, nongovernmental organizations, and stakeholders can be expanded to the entire sagebrush biome to benefit the people and wildlife that depend on this ecosystem. This report is organized into 3 parts.
Part I. Importance of the Sagebrush Biome to People and Wildlife; Part II. Change Agents in the Sagebrush Biome—Extent, Impacts, and Effort to Address Them; and Part III. Current Conservation Paradigm and Other Conservation Needs for Sagebrush
The Oregon SageCon Partnership met November 2-3, 2022, in Burns, Oregon. You can access presentations, resources, and recordings using the link provided.
- Connect local, state, and federal partners working toward resilient rangelands in southeastern Oregon and across the Great Basin.
- Share information, ideas and resources to leverage our collective knowledge, with an emphasis on strategies for addressing invasive annual grasses in our rangelands.
- Inspire action and support collaborative efforts in 2023 and beyond.
We investigated habitat selection by 28 male greater sage-grouse during each of 3 years after a 113,000-ha wildfire in a sagebrush steppe ecosystem in Idaho and Oregon. During the study period, seeding and herbicide treatments were applied for habitat restoration. We evaluated sage-grouse responses to vegetation and post-fire restoration treatments. Throughout the 3 years post-fire, sage-grouse avoided areas with high exotic annual grass cover but selected strongly for recovering sagebrush and moderately strongly for perennial grasses. By the third year post-fire, they preferred high-density sagebrush, especially in winter when sagebrush is the primary component of the sage-grouse diet. Sage-grouse preferred forb habitat immediately post-fire, especially in summer, but this selection preference was less strong in later years. They also selected areas that were intensively treated with herbicide and seeded with sagebrush, grasses, and forbs, although these responses varied with time since treatment.
Description: Effects of juniper encroachment and removal on multiple wildlife species in the Steens Mountains area and quantifying effects of grazing on sagebrush ecosystems and associated wildlife.
Presenter: Vanessa Schroeder is a faculty research assistant at Eastern Oregon Agricultural Research Center-Burns, which is in the heart of Oregons’s sagebrush country. She holds a master’s degree in Wildlife Science from OSU.
This Science for Resource Managers tool provides online, searchable access to multiple published annotated bibliographies on priority management topics for resource managers, currently focused primarily on issues relevant to lands in the western U.S.