Search

Context: Landscape composition and configuration are essential factors for species distribution and persistence. Disturbance changes landscapes and can impact individuals' movement and space use based on mobility with tradeoffs between resource acquisition and survival. Objectives: We evaluated how spring space use and survival of female sage-grouse varied depending on the composition and configuration of disturbances within sagebrush and non-sagebrush dominated habitats, and whether the size of spring neighborhoods affected survival. Methods: We created annual spring neighborhoods for individual female sage-grouse using location data from GPS-marked birds. We calculated the proportion, clumpiness, and interspersion and juxtaposition index (IJI) for each cover class within each neighborhood. We used linear mixed and Cox proportional hazards models to examine the interactive effects of composition and configuration on the area of space use and cumulative survival. Results: Spring neighborhood size decreased when the proportion and interspersion of non-sagebrush and sagebrush cover was high but increased when interspersion was low. Neighborhood size decreased when interspersion and proportion of anthropogenic footprint was high but increased when proportion was low. Sage-grouse survival decreased as the proportion of anthropogenic footprint increased, regardless of configuration. Survival decreased when the proportion of juniper cover was high, and interspersion was moderate. Females that spent more time on nest had smaller neighborhood sizes and were more likely to survive during the spring season. However, there was no effect of neighborhood size on survival. Conclusions: Our results indicate that heterogeneity of habitat and disturbance reduces spring neighborhood size and decreases spring survival of female sage-grouse. These results suggest that management actions should focus on reducing pinyon-juniper where interspersion is high and reducing or removing anthropogenic disturbance near sage-grouse breeding areas. [ABSTRACT FROM AUTHOR]

Many revegetation projects are intended to benefit wildlife species. Yet, there are few a priori evaluations that assess the potential efficiency of restoration actions in recovering wildlife habitats. We developed a spatial vegetation–habitat recovery model to gauge the degree to which field planting strategies could be expected to recover multi-factor habitat conditions for wildlife following wildfires. We simulated a wildfire footprint, multiple sagebrush (Artemisia spp.) planting scenarios, and tracked projected vegetation growth for 15 years post-fire. We used a vegetation transition framework to track and estimate the degree to which revegetation could accelerate habitat restoration for a Greater sage-grouse (Centrocercus) population within the Great Basin, western United States. We assessed the amount of habitat 15 years post-fire to estimate the degree to which revegetation could be expected to accelerate habitat restoration. Our results highlight a potential disconnect between the expansive areas required by wide-ranging wildlife such as sage-grouse and the relatively small areas that planting treatments have created. Habitat restorations and planting strategies that are intended to benefit sage-grouse may only speed up localized habitat restoration. This study provides an example of how linked revegetation–habitat modeling approaches can scope the expected return on restoration investment for habitat improvements and support the strategic use of limited restoration resources.

Many revegetation projects are intended to benefit wildlife species. Yet, there are few a priori evaluations that assess the potential efficiency of restoration actions in recovering wildlife habitats. We developed a spatial vegetation–habitat recovery model to gauge the degree to which field planting strategies could be expected to recover multi-factor habitat conditions for wildlife following wildfires. We simulated a wildfire footprint, multiple sagebrush (Artemisia spp.) planting scenarios, and tracked projected vegetation growth for 15 years post-fire. We used a vegetation transition framework to track and estimate the degree to which revegetation could accelerate habitat restoration for a Greater sage-grouse (Centrocercus) population within the Great Basin, western United States. We assessed the amount of habitat 15 years post-fire to estimate the degree to which revegetation could be expected to accelerate habitat restoration. Our results highlight a potential disconnect between the expansive areas required by wide-ranging wildlife such as sage-grouse and the relatively small areas that planting treatments have created. Habitat restorations and planting strategies that are intended to benefit sage-grouse may only speed up localized habitat restoration. This study provides an example of how linked revegetation–habitat modeling approaches can scope the expected return on restoration investment for habitat improvements and support the strategic use of limited restoration resources. [ABSTRACT FROM AUTHOR]

Conservation translocations are an important conservation tool commonly employed to augment declining or reestablish extirpated populations. One goal of augmentation is to increase genetic diversity and reduce the risk of inbreeding depression (i.e., genetic rescue). However, introducing individuals from significantly diverged populations risks disrupting coadapted traits and reducing local fitness (i.e., outbreeding depression). Genetic data are increasingly more accessible for wildlife species and can provide unique insight regarding the presence and retention of introduced genetic variation from augmentation as an indicator of effectiveness and adaptive similarity as an indicator of source and recipient population suitability. We used 2 genetic data sets to evaluate augmentation of isolated populations of greater sage‐grouse (Centrocercus urophasianus) in the northwestern region of the species range (Washington, USA) and to retrospectively evaluate adaptive divergence among source and recipient populations. We developed 2 statistical models for microsatellite data to evaluate augmentation outcomes. We used one model to predict genetic diversity after augmentation and compared these predictions with observations of genetic change. We used the second model to quantify the amount of observed reproduction attributed to transplants (proof of population integration). We also characterized genome‐wide adaptive divergence among source and recipient populations. Observed genetic diversity (HO = 0.65) was higher in the recipient population than predicted had no augmentation occurred (HO = 0.58) but less than what was predicted by our model (HO = 0.75). The amount of shared genetic variation between the 2 geographically isolated resident populations increased, which is evidence of periodic gene flow previously assumed to be rare. Among candidate adaptive genes associated with elevated fixation index (FST) (143 genes) or local environmental variables (97 and 157 genes for each genotype–environment association method, respectively), we found clusters of genes with related functions that may influence the ability of transplants to use local resources and navigate unfamiliar environments and their reproductive potential, all possible reasons for low genetic retention from augmentation. [ABSTRACT FROM AUTHOR]

Terrestrial arthropods are a critical component of sagebrush ecosystems and serve as a key food source for higher trophic levels, including many avian species of conservation concern. The North American sagebrush (Artemisia sp.) biome is in peril, threatened in part by the phenomenon of juniper encroachment. Removal of encroached juniper (Juniperus sp.) has been used by land managers as a widespread restoration technique in sagebrush ecosystems, however, the impact of this restoration action on the arthropod community has not been thoroughly examined. In 2020 and 2021, we studied surface-active arthropod response to juniper treatment in the sagebrush of northern Nevada and northeastern California. Juniper treatments completed between 2008 and 2020 were sampled to assess the impact of this restoration action on the arthropod community over time. Surface-active arthropods were more than twice as abundant in treated sites as untreated sites, however, arthropod taxa diversity was lower in treated sites than untreated sites, despite significantly higher taxa richness in treated sites. Our results suggest that juniper treatments that increase arthropod abundance or diversity may benefit insectivorous sagebrush wildlife by increasing food availability, including for species of conservation concern such as the greater sage-grouse (Centrocercus urophasianus).

Highly seasonal environments can increase competition among herbivores for nutrients, affecting rates of reproduction and survival. There is concern about the impacts of non‐native ungulates on Greater Sage‐grouse in the Great Basin of North America. We estimated nesting propensity, the annual proportion of females attempting a nest, for Greater Sage‐grouse in relation to the abundance of ungulates using 7 years of data from the northwestern Great Basin, USA. We focused on nesting because it is the necessary first major investment required for the production of new recruits. We used a Bayesian multistratum model to investigate the effects of weather and sympatric non‐native herbivores, free‐roaming horses and domestic cattle, on reproductive rates and female survival of adult and yearling sage‐grouse. Adults nested at a higher rate (0.931, 95% CI, 0.904–0.953) than yearlings (0.867, 95% CI, 0.802–0.922) under average conditions of covariates other than age. If the first nest failed, renesting rates were similar between adults (0.349, 95% CI, 0.292–0.410) and yearlings (0.353, 95% CI, 0.217–0.507). Females in better body condition at the start of the season nested at higher rates, and moderately snowy winters led to the highest nesting propensity during the following spring. Drier conditions led to low rates of nesting, particularly in areas with dense cattle grazing. Female survival was lower for nesting females, indicating a survival cost of reproduction. Areas with abundant free‐roaming horses had slightly higher nesting propensity, though other research suggests negative impacts later in the breeding cycle. Sage‐grouse face life history trade‐offs that may be shifting due to changing climatic conditions. Our work suggests that the effects of competition with non‐native ungulates on sage‐grouse life histories may be exacerbated by adverse weather. [ABSTRACT FROM AUTHOR]

Genetic variation is a well‐known indicator of population fitness yet is not typically included in monitoring programs for sensitive species. Additionally, most programs monitor populations at one scale, which can lead to potential mismatches with ecological processes critical to species' conservation. Recently developed methods generating hierarchically nested population units (i.e., clusters of varying scales) for greater sage‐grouse (Centrocercus urophasianus) have identified population trend declines across spatiotemporal scales to help managers target areas for conservation. The same clusters used as a proxy for spatial scale can alert managers to local units (i.e., neighborhood‐scale) with low genetic diversity, further facilitating identification of management targets. We developed a genetic warning system utilizing previously developed hierarchical population units to identify management‐relevant areas with low genetic diversity within the greater sage‐grouse range. Within this warning system we characterized conservation concern thresholds based on values of genetic diversity and developed a statistical model for microsatellite data to robustly estimate these values for hierarchically nested populations. We found that 41 of 224 neighborhood‐scale clusters had low genetic diversity, 23 of which were coupled with documented local population trend decline. We also found evidence of cross‐scale low genetic diversity in the small and isolated Washington population, unlikely to be reversed through typical local management actions alone. The combination of low genetic diversity and a declining population suggests relatively high conservation concern. Our findings could further facilitate conservation action prioritization in combination with population trend assessments and (or) local information, and act as a base‐line of genetic diversity for future comparison. Importantly, the approach we used is broadly applicable across taxa. [ABSTRACT FROM AUTHOR]

A fundamental goal of population ecologists is to identify drivers responsible for temporal variation in abundance. Understanding whether variation is associated with environmental stochasticity or anthropogenic disturbances, which are more amenable to management action, is crucial yet difficult to achieve. Here, we present a hierarchical monitoring framework that models rates of change in abundance from spatially structured populations and identifies when local declines fall out of synchrony with trends at larger spatial scales. Importantly, the framework provides signals that alert managers to the categorical significance of observed declines while avoiding signals where declines result from drivers operating at larger spatial scales (e.g., periodic reductions in primary productivity owing to drought). We demonstrate utility through application to a rapidly declining sagebrush (Artemisia spp.) indicator species (greater sage-grouse; Centrocercus urophasianus) using 30 years (1990–2019) of count data collected from greater than 4,400 leks (habitual breeding sites) distributed across the western United States. Results revealed population declines, immediately preceding triggers (2–4-year period), ranging between 58 and 68%. Conversely, population trends unassociated with triggers showed little-to-no sign of decline. Retrospective application of the monitoring framework indicated an average annual rate of 1.7% of leks or 1.3% of neighborhood clusters (lek aggregations) would have required management intervention to reverse range-wide declines and stabilize the U.S. population as a whole.

Ecologists often estimate population trends of animals in time series of counts using linear regression to estimate parameters in a linear transformation of multiplicative growth models, where logarithms of rates of change in counts in time intervals are used as response variables. We present quantile regression estimates for the median (0.50) and interquartile (0.25, 0.75) relationships as an alternative to mean regression estimates for common density‐dependent and density‐independent population growth models. We demonstrate that the quantile regression estimates are more robust to outliers and require fewer distributional assumptions than conventional mean regression estimates and can provide information on heterogeneous rates of change ignored by mean regression. We provide quantile regression trend estimates for 2 populations of greater sage‐grouse (Centrocercus urophasianus) in Wyoming, USA, and for the Crawford population of Gunnison sage‐grouse (Centrocercus minimus) in southwestern Colorado, USA. Our selected Gompertz models of density dependence for both populations of greater sage‐grouse had smaller negative estimates of density‐dependence terms and less variation in corresponding predicted growth rates (λ) for quantile than mean regression models. In contrast, our selected Gompertz models of density dependence with piecewise linear effects of years for the Crawford population of Gunnison sage‐grouse had predicted changes in λ across years from quantile regressions that varied more than those from mean regression because of heterogeneity in estimated λs that were both less and greater than mean estimates. Our results add to literature establishing that quantile regression provides better behaved estimates than mean regression when there are outlying growth rates, including those induced by adjustments for zeros in the time series of counts. The 0.25 and 0.75 quantiles bracketing the median provide robust estimates of population changes (λ) for the central 50% of time series data and provide a 50% prediction interval for a single new prediction without making parametric distributional assumptions or assuming homogeneous λs. Compared to mean estimates, our quantile regression trend estimates for greater sage‐grouse indicated less variation in density‐dependent λs by minimizing sensitivity to outlying values, and for Gunnison sage‐grouse indicated greater variation in density‐dependent λs associated with heterogeneity among quantiles. [ABSTRACT FROM AUTHOR]

Studying wildlife–habitat relationships at the edges of their range can provide valuable insights into the environmental factors limiting wildlife distributions and most likely to drive extirpations and range shifts in response to landscape change. Yet the relative impact of those factors is likely different along the range margin, so it is important to identify the limitations to suitable habitat at both regional and local scales. Some of the most drastic impacts of large‐scale landscape changes in North America have occurred and are forecasted in the sagebrush steppe ecosystems, where species unable to seek new habitat in the fragmented landscape will be vulnerable to climatic extremes, vegetation community shifts, and anthropogenic land use change. One of the species likely under major threat from landscape changes is the greater sage‐grouse (Centrocercus urophasianus), a sagebrush obligate with habitat constraints that make it susceptible to habitat loss impacts as sagebrush systems contract and fragment at their southern range margin, already naturally fragmented. In this study, we evaluated factors of topography and land cover directly impacting habitat selection by sage‐grouse in four study areas along their lagging range edge. We used >116,000 GPS locations from >90 grouse across four study areas in southern Utah and Nevada from 2014 to 2020 in habitat selection analyses using random forest models. Our results showed that sage‐grouse exploit topography and sagebrush cover, possibly to break predator sight lines and moderate the risk posed by avian predators using tree perches, complicating the effects of tree cover and conifer encroachment into sagebrush habitat. We found similar trends across all four study areas, suggesting sage‐grouse along the southern range margin face similar limitations. However, the effects were nonlinear and varied—models trained in one study area were only moderately successful at predicting selection in others. The local idiosyncrasies along this southern range margin indicate a need for place‐based conservation for sage‐grouse and other potentially imperiled species. Incorporating new understandings of local impacts will refine regional and range‐wide models and support efforts to effectively create habitat and plan for range shifts by vulnerable species in response to environmental change. [ABSTRACT FROM AUTHOR]

Wildlife space use is driven by three primary mechanisms, predator avoidance, foraging, and thermoregulation. The latter has largely been overlooked in wildlife research. Understanding how habitat use is influenced by thermoregulatory properties is a critical component to depicting species' ecology. Galliformes' (i.e., ground nesting birds with precocial young) ecology is predisposed to thermal extremes, where newly hatched chicks are unable to thermoregulate <14 d post-hatch, and have limited capabilities until >21 d post-hatch. We examined greater sage-grouse (Centrocercus urophasianus) brood rearing habitats and provide the first evaluation as to how microscale thermal environments influenced habitat selection. We monitored 24 broods, collected 82,929 black bulb temperature measurements from thermal arrays (n = 256) comprised of stainless steel black bulbs (i.e., surrogate for operative temperature) to compare brood morning (i.e., foraging, n = 78), afternoon (i.e., loafing, n = 82) and associated random locations (n = 96) between early (≤21 d post-hatch) and late (>21 d post-hatch) brood-rearing. We measured vegetation at all locations to disentangle relationships between cover and thermoregulatory metrics. We found that microclimates at all foraging locations heated more rapidly than either their loafing or random locations. Alternatively, loafing locations moderated ambient temperature more effectively than foraging locations but were similar to random locations. Broods were using loafing sites that both increased their ability to avoid predators (i.e., increased shrub structure) and buffered ambient temperature better than their foraging locations. Interestingly, random afternoon locations tended to lack concealment from predators, despite these locations showing improved thermal buffering compared to foraging locations. However, early brood-rearing habitats appeared to moderate ambient temperatures more effectively than late. Our results suggested that managing vegetation for structural heterogeneity will afford a diversity of thermal refuge for greater sage-grouse broods during this critical life history stage. • Foraging sites of greater sage-grouse broods heated more rapidly than the surrounding landscape. • Loafing sites moderated ambient temperature more effectively than foraging sites. • Loafing sites offered greater opportunities for refuge at thermal extremes. • Vegetation structure and thermal buffering provided escape cover from predators and more efficient thermal regulation. [ABSTRACT FROM AUTHOR]

Population growth and fitness are typically most sensitive to adult survival in long‐lived species, but variation in recruitment often explains most of the variation in fitness, as past selection has canalized adult survival. Estimating juvenile survival until age of independence has proven challenging, because marking individuals in this age class may directly affect survival. For Greater Sage‐grouse, uniquely marking juveniles in the first days of life likely results in adverse effects to survival, detection of juveniles is not perfect, and females adopt juveniles from other parents. These challenges are encountered by researchers studying avian and mammalian species with similar life histories, yet methods do not exist that explicitly estimate all these components of the recruitment process. We propose a novel data collection method and demographic model to simultaneously estimate rates of detection, survival, and adoption of juvenile individuals. Using multiple cameras to film the beginning of juvenile activity on specific days, we obtained counts of juveniles associated with marked females. Increases of juveniles to broods provided information that enabled us to estimate rates of adoption that can be applied at the population level. Losses from broods informed apparent survival. These losses could be attributed to death, or they could be chicks that were adopted by other females. We found evidence that apparent survival of juveniles was influenced by localized weather patterns when chicks were young. Similarly, we found that young chicks were more susceptible to the adverse effect of attending females being flushed by an observer. Both of these patterns diminished quickly as chicks aged. We provide the first‐ever estimates of interval‐specific adoption rates. Our results suggest that researchers should be cautious when designing studies to estimate juvenile survival. More importantly, they provide insight into adoption, a behavior that has been known to exist for decades. [ABSTRACT FROM AUTHOR]

Identifying and quantifying the extent to which landscape‐level habitat variables drive the spatial distribution of individuals across a region can provide fundamental insights into a species ecology and be essential to wildlife management and conservation plans. Although the preferences for habitat resources and the resources themselves are not static over time, most research at large spatial scales does not consider seasonal effects nor quantify annual temporal variability in the spatial distribution of habitat resources. In this study, we used a machine learning (boosted regression trees [BRTs]) and generalized linear mixed model (GLMM) approach to quantify seasonal habitat selection across three life stages (nest, late brood, and winter habitat) of sage‐grouse and estimated annual stability across a 13‐year dataset in south‐central Wyoming. Generalized linear mixed models had high area under the curve (AUC) values, but were not as high as the BRT models that had mean AUC values of 0.86, 0.81, and 0.87 for nest, late brood, and winter habitat, respectively. Generalized linear mixed models and BRT result provided similar results, but because of the higher validation values of the BRT models, we assessed annual variation by predicting the BRT models across years. We found significant spatial trends in the distribution of nesting habitat, with general decreases in the relative probability of use across the core of the study area and corresponding increases in selection on the periphery. The primary temporally shifting variables for the nesting BRT models were development, Normalized Difference Vegetation Index, and topographic wetness, suggesting they were shifting out of preferable ranges for these variables as habitat suitability was decreased over the course of our study. Winter habitat appeared to have similar spatial changes in probability of selection, but these changes were likely related to changes in winter precipitation and snow depth, which were the primary contributors to the winter BRT models. The annual dynamics of habitat selection are seldom addressed in large‐scale research but can have potentially dramatic influences on our identification of preferred habitats. [ABSTRACT FROM AUTHOR]

Abstract Population growth and fitness are typically most sensitive to adult survival in long‐lived species, but variation in recruitment often explains most of the variation in fitness, as past selection has canalized adult survival. Estimating juvenile survival until age of independence has proven challenging, because marking individuals in this age class may directly affect survival. For Greater Sage‐grouse, uniquely marking juveniles in the first days of life likely results in adverse effects to survival, detection of juveniles is not perfect, and females adopt juveniles from other parents. These challenges are encountered by researchers studying avian and mammalian species with similar life histories, yet methods do not exist that explicitly estimate all these components of the recruitment process. We propose a novel data collection method and demographic model to simultaneously estimate rates of detection, survival, and adoption of juvenile individuals. Using multiple cameras to film the beginning of juvenile activity on specific days, we obtained counts of juveniles associated with marked females. Increases of juveniles to broods provided information that enabled us to estimate rates of adoption that can be applied at the population level. Losses from broods informed apparent survival. These losses could be attributed to death, or they could be chicks that were adopted by other females. We found evidence that apparent survival of juveniles was influenced by localized weather patterns when chicks were young. Similarly, we found that young chicks were more susceptible to the adverse effect of attending females being flushed by an observer. Both of these patterns diminished quickly as chicks aged. We provide the first‐ever estimates of interval‐specific adoption rates. Our results suggest that researchers should be cautious when designing studies to estimate juvenile survival. More importantly, they provide insight into adoption, a behavior that has been known to exist for decades.

Abstract Identifying and quantifying the extent to which landscape‐level habitat variables drive the spatial distribution of individuals across a region can provide fundamental insights into a species ecology and be essential to wildlife management and conservation plans. Although the preferences for habitat resources and the resources themselves are not static over time, most research at large spatial scales does not consider seasonal effects nor quantify annual temporal variability in the spatial distribution of habitat resources. In this study, we used a machine learning (boosted regression trees [BRTs]) and generalized linear mixed model (GLMM) approach to quantify seasonal habitat selection across three life stages (nest, late brood, and winter habitat) of sage‐grouse and estimated annual stability across a 13‐year dataset in south‐central Wyoming. Generalized linear mixed models had high area under the curve (AUC) values, but were not as high as the BRT models that had mean AUC values of 0.86, 0.81, and 0.87 for nest, late brood, and winter habitat, respectively. Generalized linear mixed models and BRT result provided similar results, but because of the higher validation values of the BRT models, we assessed annual variation by predicting the BRT models across years. We found significant spatial trends in the distribution of nesting habitat, with general decreases in the relative probability of use across the core of the study area and corresponding increases in selection on the periphery. The primary temporally shifting variables for the nesting BRT models were development, Normalized Difference Vegetation Index, and topographic wetness, suggesting they were shifting out of preferable ranges for these variables as habitat suitability was decreased over the course of our study. Winter habitat appeared to have similar spatial changes in probability of selection, but these changes were likely related to changes in winter precipitation and snow depth, which were the primary contributors to the winter BRT models. The annual dynamics of habitat selection are seldom addressed in large‐scale research but can have potentially dramatic influences on our identification of preferred habitats.

Abstract The “green wave” hypothesis posits that during spring consumers track spatial gradients in emergent vegetation and associated foraging opportunities. This idea has largely been invoked to explain animal migration patterns, yet the general phenomenon underlies trends in vertebrate reproductive chronology as well. We evaluated the utility of this hypothesis for predicting spatial variation in nest initiation of greater sage‐grouse (Centrocerus urophasianus), a species of conservation concern in western North America. We used the Normalized Difference Vegetation Index (NDVI) to map the green wave across elevation and then compiled dates and locations of >450 sage‐grouse nests from 20 study sites (2000–2014) to model nest initiation as a function of the start of the growing season (SOS), defined here as the maximum daily rate of increase in NDVI. Individual sites were drawn from three ecoregions, distributed over 4.5° latitude, and spanning 2,300 m in elevation, which captured the climatic, edaphic, and floristic diversity of sagebrush ecosystems in the southern half of current sage‐grouse range. As predicted, SOS displayed a significant, positive relationship with elevation, occurring 1.3 days later for each 100 m increase in elevation. In turn, sage‐grouse nest initiation followed SOS by 22 ± 10 days (r2 = .57), with hatch dates falling on or just prior to the peak of the growing season. By timing nesting to the green wave, sage‐grouse chicks hatched when the abundance of protein‐rich invertebrate biomass is hypothesized to be nearing a seasonal high. This adaptation likely represents a strategy for maximizing reproductive success in the arid, variable environments that define sagebrush ecosystems. Given projected changes in climate and land use, these results can be used to predict periods of relative sensitivity to habitat disturbance for sage‐grouse. Moreover, the near real‐time availability of satellite imagery offers a heretofore underutilized means of mapping the green wave, planning habitat restoration, and monitoring range conditions.

Abstract Defining boundaries of species' habitat across broad spatial scales is often necessary for management decisions, and yet challenging for species that demonstrate differential variation in seasonal habitat use. Spatially explicit indices that incorporate temporal shifts in selection can help overcome such challenges, especially for species of high conservation concern. Greater sage‐grouse Centrocercus urophasianus (hereafter, sage‐grouse), a sagebrush obligate species inhabiting the American West, represents an important case study because sage‐grouse exhibit seasonal habitat patterns, populations are declining in most portions of their range and are central to contemporary national land use policies. Here, we modeled spatiotemporal selection patterns for telemetered sage‐grouse across multiple study sites (1,084 sage‐grouse; 30,690 locations) in the Great Basin. We developed broad‐scale spatially explicit habitat indices that elucidated space use patterns (spring, summer/fall, and winter) and accounted for regional climatic variation using previously published hydrographic boundaries. We then evaluated differences in selection/avoidance of each habitat characteristic between seasons and hydrographic regions. Most notably, sage‐grouse consistently selected areas dominated by sagebrush with few or no conifers but varied in type of sagebrush selected by season and region. Spatiotemporal variation was most apparent based on availability of water resources and herbaceous cover, where sage‐grouse strongly selected upland natural springs in xeric regions but selected larger wet meadows in mesic regions. Additionally, during the breeding period in spring, herbaceous cover was selected strongly in the mesic regions. Lastly, we expanded upon an existing joint–index framework by combining seasonal habitat indices with a probabilistic index of sage‐grouse abundance and space use to produce habitat maps useful for sage‐grouse management. These products can serve as conservation planning tools that help predict expected benefits of restoration activities, while highlighting areas most critical to sustaining sage‐grouse populations. Our joint–index framework can be applied to other species that exhibit seasonal shifts in habitat requirements to help better guide conservation actions.

The U.S. federal government has recently committed to the difficult task of slowing and managing the invasive grass‐fire cycle in sagebrush steppe, where property, livelihoods, and entire ecosystems are at risk. To safely manage this crisis, the government recently proposed to construct about 17,700 km of fuel breaks and millions of hectares of fuel reduction treatments in six western states. A challenge for resource managers will be the strategic placement of these land treatments. We investigated the need for this massive effort from the perspective of protecting previous rehabilitation and restoration seeding investments, including over 3,400 seedings implemented from 1990 to 2019 covering about 24,540 km2. We found that portions of over 26% of these seedings have since burned representing nearly 17% of this seeded area. Locations that had recurrent wildfire had repeat treatments and thus multiple investments in the same location. Our analysis supports the management actions aimed at protecting remaining sagebrush and restoration investments, especially in areas where the invasive grass‐fire cycle is most pervasive. Given the decades required for most sagebrush to recover after wildfire, the urgency of this management intervention is evident. The specific details, placement, and effectiveness of these interventions could influence outcomes and potential unintended consequences. [ABSTRACT FROM AUTHOR]

Abstract The U.S. federal government has recently committed to the difficult task of slowing and managing the invasive grass‐fire cycle in sagebrush steppe, where property, livelihoods, and entire ecosystems are at risk. To safely manage this crisis, the government recently proposed to construct about 17,700 km of fuel breaks and millions of hectares of fuel reduction treatments in six western states. A challenge for resource managers will be the strategic placement of these land treatments. We investigated the need for this massive effort from the perspective of protecting previous rehabilitation and restoration seeding investments, including over 3,400 seedings implemented from 1990 to 2019 covering about 24,540 km2. We found that portions of over 26% of these seedings have since burned representing nearly 17% of this seeded area. Locations that had recurrent wildfire had repeat treatments and thus multiple investments in the same location. Our analysis supports the management actions aimed at protecting remaining sagebrush and restoration investments, especially in areas where the invasive grass‐fire cycle is most pervasive. Given the decades required for most sagebrush to recover after wildfire, the urgency of this management intervention is evident. The specific details, placement, and effectiveness of these interventions could influence outcomes and potential unintended consequences.

Abstract Variation in nutrient allocation can influence the timing of breeding and ultimately reproductive output. Time and space constraints might exist, however, if fewer food resources are available to meet the costs of reproduction early during the reproductive season. Here, for the first time, we test whether nutrient‐allocation strategies for reproduction in a shrub‐dependent avian species differ with timing of breeding in different ecoregions: a high‐elevation landscape, containing spatially complex vegetation (Rocky Mountains) vs. a low‐elevation, more homogenous landscape (Great Plains). We analyzed data collected from radio‐telemetry and stable isotopes to assess the degree to which endogenous (body) reserves are used for reproduction and whether variation in allocation strategies was associated with time of year, ecoregion, habitat quality (including sagebrush type and plant greenness), or maternal characteristics. Using a Bayesian statistical framework, we found that females relied on a similar amount of endogenous reserves for reproduction in first nesting and renesting attempts. Additionally, endogenous contributions declined more rapidly throughout the nesting season in the Rocky Mountains than in the Great Plains. Individuals in high‐ and intermediate‐elevation sagebrush types in the Rocky Mountains used similar amounts of endogenous reserves, whereas females nesting in low‐elevation sagebrush used less. Females nesting at intermediate elevations, which experience the greatest flush of new green vegetation during the nesting season, switched their reliance from endogenous‐to‐exogenous sources for reproduction as green vegetation became available during spring. Our study highlights adaptations of a nutrient‐allocation strategy across areas with varying levels of resources in time and space in a habitat specialist bird. Nutrient allocation by individuals residing in high‐elevation areas favors a strategy that mainly uses nutrients gained from wintering habitats, whereas individuals residing in low‐elevation areas mainly use exogenous sources for reproduction.

In recent decades, feral horse (Equus caballus; horse) populations increased in sagebrush (Artimesia spp.) ecosystems, especially within the Great Basin, to the point of exceeding maximum appropriate management levels (AMLmax), which were set by land administrators to balance resource use by feral horses, livestock, and wildlife. Concomitantly, greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) are sagebrush obligates that have experienced population declines within these same arid environments as a result of steady and continued loss of seasonal habitats. Although a strong body of research indicates that overabundant populations of horses degrade sagebrush ecosystems, empirical evidence linking horse abundance to sage‐grouse population dynamics is missing. Within a Bayesian framework, we employed state‐space models to estimate population rate of change (λ) using 15 years (2005–2019) of count surveys of male sage‐grouse at traditional breeding grounds (i.e., leks) as a function of horse abundance relative to AMLmax and other environmental covariates (e.g., wildfire, precipitation, % sagebrush cover). Additionally, we employed a post hoc impact‐control design to validate existing AMLmax values as related to sage‐grouse population responses, and to help control for environmental stochasticity and broad‐scale oscillations in sage‐grouse abundance. On average, for every 50% increase in horse abundance over AMLmax, our model predicted an annual decline in sage‐grouse abundance by 2.6%. Horse abundance at or below AMLmax coincided with sage‐grouse λ estimates that were consistent with trends at non‐horse areas elsewhere in the study region. Thus, AMLmax, as a whole, appeared to be set adequately in preventing adverse effects to sage‐grouse populations. Results indicated 76%, 97%, and >99% probability of sage‐grouse population decline relative to controls when horse numbers are 2, 2.5, and ≥3 times over AMLmax, respectively. As of 2019, horse herds exceeded AMLmax in Nevada, USA, by >4 times on average across all horse management areas. If feral horse populations continue to grow at current rates unabated, model projections indicate sage‐grouse populations will be reduced within horse‐occupied areas by >70.0% by 2034 (15‐year projection), on average compared to 21.2% estimated for control sites. A monitoring framework that improves on estimating horse abundance and identifying responses of sage‐grouse and other key indicator species (plant and animal) would be beneficial to guide management decisions that promote co‐occurrence of horses with sensitive wildlife and livestock within landscapes subjected to multiple uses. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society. : We evaluated the influences of feral horse abundance on the population dynamics of greater sage‐grouse. Sage‐grouse population abundance declined substantially when horse abundance increased above maximum appropriate management levels established by the Bureau of Land Management. Results can be used to identify management actions that preserve a balance between the presence of feral horses, other managed livestock, and native wildlife within sagebrush ecosystems. [ABSTRACT FROM AUTHOR]

Perennially and intermittently available water in lentic, spring‐fed herbaceous meadows supports wetland plants that build and maintain absorbent soil organic matter, capture sediment, prevent erosion, and thereby sustain riparian ecosystems. Enhanced forage and available water attract a diversity of wildlife and grazing animals that can degrade riparian vegetation through prolonged overuse. We tested novel monitoring methods and adapted existing methods to obtain quantified vegetation data that have been consistently linked to riparian functionality and compared these data to ungulate species use. We quantified ungulate use with time‐lapse cameras at 10 Nevada spring‐fed herbaceous meadows where core greater sage‐grouse (Centrocercus urophasianus) habitat, public land grazing allotments, and free‐roaming horse (Equus caballus) herd management areas (Bureau of Land Management) or territories (U.S. Department of Agriculture Forest Service) overlapped. Free‐roaming horses used most study sites over longer periods and grazed more intensely than cattle or domestic sheep. Native ungulate grazing intensity was comparatively negligible. Free‐roaming horses selected spring‐fed meadow sites on average 51 (±33 [SE]) times more than the surrounding rangelands, and cattle selected them 30 ± 23 times more. Within the wettest area of a site, study sites with longer duration of use and higher intensity of use had more soil alteration and bare ground. Riparian ecosystem degradation occurred where meadows had limited rest or recovery time from grazing during the growing season. At all sites we noted loss of riparian function, especially within the hydric areas with the highest potential to grow abundant cover of stabilizing wetland plant species. Transects for monitoring soil alteration and vegetation cover in this hydric location can provide a leading indicator of riparian recovery or degradation and help in adjusting free‐roaming horse population levels or livestock management strategies. © 2021 The Wildlife Society. : Horse and cattle grazing throughout the grazing season impaired functioning of spring‐fed herbaceous meadows across Nevada, USA. The wettest portion of the meadow provided a clear signal we could relate to animal use and wetland function. [ABSTRACT FROM AUTHOR]

Variation in nutrient allocation can influence the timing of breeding and ultimately reproductive output. Time and space constraints might exist, however, if fewer food resources are available to meet the costs of reproduction early during the reproductive season. Here, for the first time, we test whether nutrient‐allocation strategies for reproduction in a shrub‐dependent avian species differ with timing of breeding in different ecoregions: a high‐elevation landscape, containing spatially complex vegetation (Rocky Mountains) vs. a low‐elevation, more homogenous landscape (Great Plains). We analyzed data collected from radio‐telemetry and stable isotopes to assess the degree to which endogenous (body) reserves are used for reproduction and whether variation in allocation strategies was associated with time of year, ecoregion, habitat quality (including sagebrush type and plant greenness), or maternal characteristics. Using a Bayesian statistical framework, we found that females relied on a similar amount of endogenous reserves for reproduction in first nesting and renesting attempts. Additionally, endogenous contributions declined more rapidly throughout the nesting season in the Rocky Mountains than in the Great Plains. Individuals in high‐ and intermediate‐elevation sagebrush types in the Rocky Mountains used similar amounts of endogenous reserves, whereas females nesting in low‐elevation sagebrush used less. Females nesting at intermediate elevations, which experience the greatest flush of new green vegetation during the nesting season, switched their reliance from endogenous‐to‐exogenous sources for reproduction as green vegetation became available during spring. Our study highlights adaptations of a nutrient‐allocation strategy across areas with varying levels of resources in time and space in a habitat specialist bird. Nutrient allocation by individuals residing in high‐elevation areas favors a strategy that mainly uses nutrients gained from wintering habitats, whereas individuals residing in low‐elevation areas mainly use exogenous sources for reproduction. [ABSTRACT FROM AUTHOR]

Animal species often have diverse requirements at different life history stages. Individuals may best meet these requirements by occupying areas with diverse heterogenous resources. Human activities such as agriculture may affect available habitat and heterogenous resources, but current understanding of possible effects is incomplete. We investigated habitat use and survival of an avian habitat specialist species with broods, the greater sage-grouse, in a landscape with different ecological types of sagebrush communities and livestock grazing. We used data from radio-collared females with broods to evaluate: 1) whether and when broods use heterogeneous resources across different sagebrush types; 2) effects of this heterogeneity on offspring fitness; and 3) management implications of our findings. Using a regression-based framework, we found that 26 of 99 broods capitalized on available heterogeneity by moving among ecologically distinct sagebrush types. The probability of switching was positively related to shrub cover and negatively related to forb cover, and distance to the nearest water tank and mesic area. Broods that switched had greater movement rates which resulted in narrower foraging niche at higher trophic levels. For broods that did not switch, survival was negatively related to Lepidoptera biomass and positively related to slope position, distance to mesic area, and accumulated grass cover. For broods that used heterogenous resources across different sagebrush types, survival remained constant across the range of observed conditions. Our findings provide rare evidence that use of heterogeneous resources can mitigate variation in change related to the environment and livestock grazing on components of offspring fitness. • Heterogeneity of habitat features can increase fitness in animals. • Human alteration including livestock grazing can affect this relationship. • Study evaluates use of heterogeneous resources on offspring fitness in grazed landscape. • Results suggest heterogeneous resources mitigate grazing effects on offspring fitness. • Conservation of heterogeneity of habitat features with implications to grazing management are discussed. [ABSTRACT FROM AUTHOR]

Abstract Understanding the genetic underpinning of adaptive divergence among populations is a key goal of evolutionary biology and conservation. Gunnison sage‐grouse (Centrocercus minimus) is a sagebrush obligate species with a constricted range consisting of seven discrete populations, each with distinctly different habitat and climatic conditions. Though geographically close, populations have low levels of natural gene flow resulting in relatively high levels of differentiation. Here, we use 15,033 SNP loci in genomic outlier analyses, genotype–environment association analyses, and gene ontology enrichment tests to examine patterns of putatively adaptive genetic differentiation in an avian species of conservation concern. We found 411 loci within 5 kbp of 289 putative genes associated with biological functions or pathways that were overrepresented in the assemblage of outlier SNPs. The identified gene set was enriched for cytochrome P450 gene family members (CYP4V2, CYP2R1, CYP2C23B, CYP4B1) and could impact metabolism of plant secondary metabolites, a critical challenge for sagebrush obligates. Additionally, the gene set was also enriched with members potentially involved in antiviral response (DEAD box helicase gene family and SETX). Our results provide a first look at local adaption for isolated populations of a single species and suggest adaptive divergence in multiple metabolic and biochemical pathways may be occurring. This information can be useful in managing this species of conservation concern, for example, to identify unique populations to conserve, avoid translocation or release of individuals that may swamp locally adapted genetic diversity, or guide habitat restoration efforts.

Abstract Background Current knowledge about seasonal variation in the gut microbiota of vertebrates is limited to a few studies based on mammalian fecal samples. Seasonal changes in the microbiotas of functionally distinct gut regions remain unexplored. We investigated seasonal variation (summer versus winter) and regionalization of the microbiotas of the crop, ventriculus, duodenum, cecum, and colon of the greater sage-grouse (Centrocercus urophasianus), an avian folivore specialized on the toxic foliage of sagebrush (Artemesia spp.) in western North America. Results We sequenced the V4 region of the 16S rRNA gene on an Illumina MiSeq and obtained 6,639,051 sequences with a median of 50,232 per sample. These sequences were assigned to 457 bacterial and 4 archaeal OTUs. Firmicutes (53.0%), Bacteroidetes (15.2%), Actinobacteria (10.7%), and Proteobacteria (10.1%)were the most abundant and diverse phyla. Microbial composition and richness showed significant differences among gut regions and between summer and winter. Gut region explained almost an order of magnitude more variance in our dataset than did season or the gut region × season interaction. The effect of season was uneven among gut regions. Microbiotas of the crop and cecum showed the greatest seasonal differences. Conclusions Our data suggest that seasonal differences in gut microbiota reflect seasonal variation in the microbial communities associated with food and water. Strong differentiation and uneven seasonal changes in the composition and richness of the microbiota among functionally distinct gut regions demonstrate the necessity of wider anatomical sampling for studies of composition and dynamics of the gut microbiota.

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Temperature at fine spatial scales is an important driver of nest site selection for many avian species during the breeding season and can influence nest success. Sagebrush (Artemisia spp.) communities have areas with high levels of vegetation heterogeneity and high thermal variation; however, fire removes vegetation that provides protection from predators and extreme environmental conditions. To examine the influence of microclimates on Greater Sage-Grouse (Centrocercus urophasianus) nest site selection and nest success in a fire-affected landscape, we measured black bulb temperature (Tbb) and vegetation attributes (e.g., visual obstruction) at 3 spatial scales (i.e. nest bowl, microsite, and landscape) in unburned and burned areas. Nest bowls exhibited greater buffering of Tbb than both nearby microsites and the broader landscape. Notably, nest bowls were warmer in cold temperatures, and cooler in hot temperatures, than nearby microsites and the broader landscape, regardless of burn stage. Nest survival (NS) was higher for nests in unburned areas compared to nests in burned areas (unburned NS = 0.43, 95% confidence interval [CI]: 0.33-0.54; burned NS = 0.24, 95% CI: 0.10-0.46). The amount of bare ground was negatively associated with NS, but effects diminished as the amount of bare ground reached low levels. Shrub height and visual obstruction were positively associated with NS during the entire study period, whereas minimum Tbb had a weaker effect. Our findings demonstrate that thermoregulatory selection by Greater Sage-Grouse at nest sites had marginal effects on their NS. However, given that increases in vegetation structure (e.g., shrub height) provide thermal refuge and increase NS, vegetation remnants or regeneration in a post-fire landscape could be critical to Greater Sage-Grouse nesting ecology. [ABSTRACT FROM AUTHOR]

Imperiled sagebrush (Artemisia spp.) ecosystems of western North America are experiencing unprecedented conservation planning efforts. Advances in decision-support tools operationalize concepts of ecosystem resilience by quantitatively linking spatially explicit variation in soil and plant processes to outcomes of biotic and abiotic disturbances. However, failure to consider higher trophic-level fauna of conservation concern in these tools can hinder efforts to operationalize resilience owing to spatiotemporal lags between slower reorganization of plant and soil processes following disturbance, and faster behavioral and demographic responses of fauna to disturbance. Here, we provide multi-scale examples of decision-support tools for management and restoration actions that evaluate general resilience mapped to variation in soil moisture and temperature regimes through new lenses of habitat selection and population performance responses for an at-risk obligate species to sagebrush ecosystems, the greater sage-grouse (Centrocercus urophasianus). We then briefly describe general pathways going forward for more explicit integration of sage-grouse fitness with factors influencing variation in sagebrush resilience to disturbance and resistance to invasive species (e.g., annual grasses). The intended product of these efforts is a more targeted operational definition of resilience for managers by using quantifiable metrics that help limit chances of spatiotemporal mismatches among restoration responses owing to differences in engineering resilience between sagebrush ecosystem processes and sage-grouse population dynamics. Moreover, spatial resilience can be promoted though explicit consideration of sage-grouse and sagebrush predicted responses to active and passive management treatments across space and time. We describe tools that include multi-scale geospatial overlays and simulation analyses of post-disturbance land cover recovery aimed at prioritizing primary threats to sagebrush ecosystems in the Great Basin in the western portion of sage-grouse range (i.e., grass-fire cycles and conifer expansion), but underlying concepts have broader application to a range of ecosystems.

The "green wave" hypothesis posits that during spring consumers track spatial gradients in emergent vegetation and associated foraging opportunities. This idea has largely been invoked to explain animal migration patterns, yet the general phenomenon underlies trends in vertebrate reproductive chronology as well. We evaluated the utility of this hypothesis for predicting spatial variation in nest initiation of greater sage‐grouse (Centrocerus urophasianus), a species of conservation concern in western North America. We used the Normalized Difference Vegetation Index (NDVI) to map the green wave across elevation and then compiled dates and locations of >450 sage‐grouse nests from 20 study sites (2000–2014) to model nest initiation as a function of the start of the growing season (SOS), defined here as the maximum daily rate of increase in NDVI. Individual sites were drawn from three ecoregions, distributed over 4.5° latitude, and spanning 2,300 m in elevation, which captured the climatic, edaphic, and floristic diversity of sagebrush ecosystems in the southern half of current sage‐grouse range. As predicted, SOS displayed a significant, positive relationship with elevation, occurring 1.3 days later for each 100 m increase in elevation. In turn, sage‐grouse nest initiation followed SOS by 22 ± 10 days (r2 =.57), with hatch dates falling on or just prior to the peak of the growing season. By timing nesting to the green wave, sage‐grouse chicks hatched when the abundance of protein‐rich invertebrate biomass is hypothesized to be nearing a seasonal high. This adaptation likely represents a strategy for maximizing reproductive success in the arid, variable environments that define sagebrush ecosystems. Given projected changes in climate and land use, these results can be used to predict periods of relative sensitivity to habitat disturbance for sage‐grouse. Moreover, the near real‐time availability of satellite imagery offers a heretofore underutilized means of mapping the green wave, planning habitat restoration, and monitoring range conditions. [ABSTRACT FROM AUTHOR]

North American sagebrush (Artemisia spp.)‐obligate birds are experiencing steep population declines due in part to increased disturbance, mainly human‐caused, across their range. At the eastern edge of the sagebrush steppe, this issue may potentially be exacerbated because of natural disturbance by black‐tailed prairie dogs (Cynomys ludovicianus). Our goal was to compare local and landscape models of habitat use by greater sage‐grouse (Centrocercus urophasianus), Brewer's sparrow (Spizella breweri), and sage thrasher (Oreoscoptes montanus) with models including effects of natural (i.e., prairie dog) and anthropogenic disturbance. We used a combination of field data collection, and state and national datasets for the Thunder Basin National Grassland, eastern Wyoming, USA, to understand the factors that influence lek attendance by sage‐grouse and habitat use by 2 passerines in this system. For all 3 species, models including big sagebrush (Artemisia tridentata) cover at local and landscape scales were the most competitive among univariate models, supporting the paradigm that sagebrush is key for these species. Models including anthropogenic disturbance (well density, road density) explained more variation than models of prairie dog disturbance alone for 2 of the 3 species, but long‐term disturbance by prairie dogs did reduce abundance of Brewer's sparrows. Although long‐term prairie dog disturbance has the potential to reduce sagebrush cover for sagebrush‐obligate birds, such events are likely rare because outbreaks of plague (Yersina pestis) and lethal control on borders with private land reduce prairie dog disturbance. Conversely, anthropogenic disturbance is slated to increase in this system, suggesting potentially accelerated declines for sagebrush birds into the future. © 2020 The Wildlife Society. Imperiled sagebrush songbirds and greater sage‐grouse are less likely to occupy disturbed habitat in northeastern Wyoming. Although these species are sensitive to both natural (prairie dog) and anthropogenic disturbance, the latter appears to play a larger role in habitat use in this region. [ABSTRACT FROM AUTHOR]

Sage‐grouse (Centrocercus spp.) are influencing rapidly evolving land management policy in the western United States. Management objectives for fine‐scale vegetation characteristics (e.g., grass height >18 cm) have been adopted by land management agencies based on resource selection or relationships with fitness proxies reported among numerous habitat studies. Some managers, however, have questioned the appropriateness of these objectives. Moreover, it remains untested whether habitat–fitness relationships documented at fine scales (i.e., among individual nests within a study area) also apply at scales of management units (e.g., pastures or grazing allotments), which are many orders of magnitude larger. We employed meta‐analyses of studies published from 1991 to 2019 to help resolve the role of fine‐scale vegetation structure in nest site selection and nest success across the geographic range of greater sage‐grouse (C. urophasianus) and evaluate the validity of established habitat management objectives. Specifically, we incorporated effects of study design and functional responses to resource availability in meta‐regression models linking vegetation structure to nest site selection, and used a novel meta‐analytic approach to simultaneously model vegetation structure and its relationship to nest success. Our approach tested habitat relationships at a range‐wide extent and a grain size closely matching scales at which agencies make management decisions. We found moderate, but context‐dependent, effects of shrub characteristics and weak effects of herbaceous vegetation on nest site selection. None of the tested vegetation characteristics were related to variation in nest success, suggesting nesting habitat–fitness relationships have been inappropriately extrapolated in developing range‐wide habitat management objectives. Our findings reveal surprising flexibility in habitat use for a species often depicted as having very particular fine‐scale habitat requirements, and cast doubt on the practice of adopting precise management objectives for vegetation structure based on findings of individual small‐scale field studies. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. Sage‐grouse offer an illustrative case of a common situation in which management objectives, based on informal synthesis of findings of small‐scale field studies, are applied across a species' range. Our meta‐analyses of sage‐grouse nesting studies revealed that widely adopted habitat management objectives prescribe a narrow range of conditions found in only a small subset of breeding habitats successfully exploited by the species across its range, and have no relationship to demographic performance. [ABSTRACT FROM AUTHOR]

Defining boundaries of species' habitat across broad spatial scales is often necessary for management decisions, and yet challenging for species that demonstrate differential variation in seasonal habitat use. Spatially explicit indices that incorporate temporal shifts in selection can help overcome such challenges, especially for species of high conservation concern. Greater sage‐grouse Centrocercus urophasianus (hereafter, sage‐grouse), a sagebrush obligate species inhabiting the American West, represents an important case study because sage‐grouse exhibit seasonal habitat patterns, populations are declining in most portions of their range and are central to contemporary national land use policies. Here, we modeled spatiotemporal selection patterns for telemetered sage‐grouse across multiple study sites (1,084 sage‐grouse; 30,690 locations) in the Great Basin. We developed broad‐scale spatially explicit habitat indices that elucidated space use patterns (spring, summer/fall, and winter) and accounted for regional climatic variation using previously published hydrographic boundaries. We then evaluated differences in selection/avoidance of each habitat characteristic between seasons and hydrographic regions. Most notably, sage‐grouse consistently selected areas dominated by sagebrush with few or no conifers but varied in type of sagebrush selected by season and region. Spatiotemporal variation was most apparent based on availability of water resources and herbaceous cover, where sage‐grouse strongly selected upland natural springs in xeric regions but selected larger wet meadows in mesic regions. Additionally, during the breeding period in spring, herbaceous cover was selected strongly in the mesic regions. Lastly, we expanded upon an existing joint–index framework by combining seasonal habitat indices with a probabilistic index of sage‐grouse abundance and space use to produce habitat maps useful for sage‐grouse management. These products can serve as conservation planning tools that help predict expected benefits of restoration activities, while highlighting areas most critical to sustaining sage‐grouse populations. Our joint–index framework can be applied to other species that exhibit seasonal shifts in habitat requirements to help better guide conservation actions. [ABSTRACT FROM AUTHOR]

Understanding the genetic underpinning of adaptive divergence among populations is a key goal of evolutionary biology and conservation. Gunnison sage‐grouse (Centrocercus minimus) is a sagebrush obligate species with a constricted range consisting of seven discrete populations, each with distinctly different habitat and climatic conditions. Though geographically close, populations have low levels of natural gene flow resulting in relatively high levels of differentiation. Here, we use 15,033 SNP loci in genomic outlier analyses, genotype–environment association analyses, and gene ontology enrichment tests to examine patterns of putatively adaptive genetic differentiation in an avian species of conservation concern. We found 411 loci within 5 kbp of 289 putative genes associated with biological functions or pathways that were overrepresented in the assemblage of outlier SNPs. The identified gene set was enriched for cytochrome P450 gene family members (CYP4V2, CYP2R1, CYP2C23B, CYP4B1) and could impact metabolism of plant secondary metabolites, a critical challenge for sagebrush obligates. Additionally, the gene set was also enriched with members potentially involved in antiviral response (DEAD box helicase gene family and SETX). Our results provide a first look at local adaption for isolated populations of a single species and suggest adaptive divergence in multiple metabolic and biochemical pathways may be occurring. This information can be useful in managing this species of conservation concern, for example, to identify unique populations to conserve, avoid translocation or release of individuals that may swamp locally adapted genetic diversity, or guide habitat restoration efforts. [ABSTRACT FROM AUTHOR]

Translocation is a vital tool in conservation and recovery programs, and knowledge of factors that determine demographic rates of translocated organisms is important for assessing the efficacy of translocations. Greater sage‐grouse (Centrocercus urophasianus) have been the subject of recent translocation efforts because of their declining range and their usefulness as an umbrella species for conservation. Using a long‐term data set on sage‐grouse in central Washington, USA, we compared movement and demographic rates of translocated and resident birds. Because newly translocated birds experience physiological stress during translocation and are released in unfamiliar habitat, we hypothesized their demographic rates would differ from residents. We analyzed 18 years of radio‐tracking data acquired from resident, newly translocated (<1 yr post‐translocation; T1), and previously translocated (>1 yr post‐translocation; T2) sage‐grouse between 1989 and 2017 to estimate movement rates, survival, and productivity. Newly translocated sage‐grouse exhibited farther daily movements (0.58 km/day) and smaller 95% home ranges (89 km2) than residents and previously translocated birds. Daily movements and sex influenced survival, but survival did not differ according to residency status. Furthermore, birds that survived to a second year after translocation exhibited shorter daily movements compared to their first year (βˆ = −0.727 ± 0.157 [SE]), which corresponded with increased survival the second year (T1 = 0.526, T2 = 0.610). This decrease in movements and increase in survival the second year was not apparent in the control group of resident birds, indicating a possible behavioral link to survival of newly translocated sage‐grouse. Most productivity metrics were similar for translocated and resident birds, except for nest propensity (i.e., nest initiation rate), which was lower for newly translocated birds (35%) compared to residents and previously translocated birds. Our results reveal that translocated sage‐grouse exhibit temporary differences in some demographic parameters in their first year, which later align with those of resident birds in subsequent years. Similarities in adult and nest survival according to residency status further suggest that translocation may prove to be a viable tool for restoring and conserving this species. Continued declines in sage‐grouse populations in Washington, however, indicate that habitat conversion and fragmentation may be reducing demographic rates of residents and translocated birds, which warrants further study. © 2019 The Wildlife Society. Sex and movement were important to sage‐grouse survival and movement differed between translocated and resident individuals. Translocated sage‐grouse adjusted to the release site after roughly 1 year and subsequently modified their movements to increase their probability of survival. [ABSTRACT FROM AUTHOR]

Terrestrial arthropods are a critical component of rangeland ecosystems that convert primary production into resources for higher trophic levels. During spring and summer, select arthropod taxa are the primary food of breeding prairie birds, of which many are imperiled in North America. Livestock grazing is globally the most widespread rangeland use and can affect arthropod communities directly or indirectly through herbivory. To examine effects of management on arthropod community structure and avian food availability, we studied ground-dwelling arthropods on grazed and ungrazed sagebrush rangelands of central Montana. From 2012 to 2015, samples were taken from lands managed as part of a rest-rotation grazing program and from idle lands where livestock grazing has been absent for over a decade. Bird-food arthropods were twice as prevalent in managed pastures despite the doubling of overall activity-density of arthropods in idle pastures. Activity-density on idled lands was largely driven by a tripling of detritivores and a doubling in predators. Predator community structure was simplified on idled lands, where Lycosid spiders increased by fivefold. In contrast, managed lands supported a more diverse assemblage of ground-dwelling arthropods, which may be particularly beneficial for birds in these landscapes if, for example, diversity promotes temporal stability in this critical food resource. Our results suggest that periodic disturbance may enhance arthropod diversity, and that birds may benefit from livestock grazing with periodic rest or deferment. [ABSTRACT FROM AUTHOR]

Abstract Animals are expected to select habitats that maximize their fitness over evolutionary time scales. Yet in human-modified landscapes, habitat selection might not always lead to increased fitness because animals undervalue high-quality resources that appear less attractive than those of lower quality. In the American West, agriculture has modified landscapes, yet little is known about whether agricultural changes alter the reliability of the cues animals use to identify habitat quality; ultimately forming maladaptive breeding strategies where behavioral cues are mismatched with survival outcomes. Using the greater sage-grouse, a species highly dependent upon sagebrush landscapes, we (1) evaluated how females select nesting habitats based on sagebrush type, along with livestock grazing related linear and point features, and other biotic, abiotic characteristics, given hypothesized influences on hiding cover, microclimate and predator travel routes and perches, (2) compared habitat selection information with results for nest survival estimates to evaluate if selection appears to be adaptive or not, and (3) used our results to evaluate the most appropriate strategies for this species in a grazing-modified landscape. Nest-site selection for sagebrush type appears to be maladaptive: in the most-preferred sagebrush type, nest survival rate was one-fourth the rate realized by females nesting in the sagebrush type avoided. Nest survival was four times higher for nests placed away from (>100 m), rather than next to (1 m), the nearest fence, and survival was lower within sites with higher cow pie density (a proxy for previous grazing intensity). Live and dead grasses influenced selection and survival in opposing ways such that dead grass was selected for but resulted in reduced survival while live grass was avoided but resulted in increased survival. Results collectively provide the first empirical evidence that a specific type of sagebrush acts as an ecological trap while another sagebrush type is undervalued. These results also suggest that adding more fences to control livestock grazing systems will likely reduce sage-grouse nest survival. Highlights • Nest survival in preferred sagebrush type was one-fourth the rate in type avoided. • Nest survival was four times higher when placed >100 m away from nearest fence. • Timing of graze could best achieve herbaceous requirements for successful nesting. • Fence modifications along with prioritization of sagebrush type are discussed. [ABSTRACT FROM AUTHOR]

Abstract The Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & A. Young] S.L. Welsh) alliance is the most extensive of the big sagebrush complex in the Intermountain West. There is a lack of information describing vegetation characteristics, diversity, and heterogeneity of the Wyoming big sagebrush alliance. We annually sampled 48 Wyoming big sagebrush plant communities over 10 yr to delineate major vegetation associations and describe their major vegetation characteristics including canopy cover, density, species richness, and yield. Six associations were identified on the basis of dominant or codominant perennial bunchgrass species, using MRPP analysis, and they included ARTRW8 (Wyoming big sagebrush)/PSSP6 (Pseudoroegneria spicata [Pursh] A. Löve, bluebunch wheatgrass), ARTRW8/ACTH7 (Achnatherum thurberianum [Piper] Barkworth, Thurber's needlegrass), ARTRW8/FEID (Festuca idahoensis Elmer, Idaho fescue), ARTRW8/HECO26 (Hesperostipa comata [Trin. & Rupr.] Barkworth, needle-and-thread), ARTRW8/PSSP6-ACTH7, and ARTRW8/PSSP6-FEID-ACTH7. On average, PSSP6 and FEID associations had the highest total herbaceous cover and annual yields and the HECO26 and ACTH7 associations had the lowest. Perennial forb cover averaged over 5% in PSSP6 and FEID associations and ranged from 0.3% to 3.5% in the other associations. Sagebrush cover was greatest in ACTH7 and PSSP6-ACTH7 and lowest in FEID and HECO26 associations. Habitat suitability criteria for sage-grouse indicated that Wyoming big sagebrush associations at the stand/site level will generally not meet breeding habitat requirements and only attain suitable habitat requirements for other life stages about 50% of the time. [ABSTRACT FROM AUTHOR]

The North American semi‐arid sagebrush, Artemisia spp., biome exhibits considerable climatic complexity driving dynamic spatiotemporal shifts in primary productivity. Greater and Gunnison sage‐grouse, Centrocercus urophasianus and C. minimus, are adapted to patterns of resource intermittence and rely on stable adult survival supplemented by occasional recruitment pulses when climatic conditions are favorable. Predictions of intensifying water scarcity raise concerns over new demographic bottlenecks impacting sage‐grouse populations in drought‐sensitive landscapes. We estimate biome‐wide mesic resource productivity from 1984 to 2016 using remote sensing to identify patterns of food availability influencing selective pressures on sage‐grouse. We linked productivity to abiotic factors to examine effects of seasonal drought across time, space, and land tenure, with findings partitioned along gradients of ecosystem water balance within Great Basin, Rocky Mountains and Great Plains regions. Precipitation was the driver of mesic resource abundance explaining ≥70% of variance in drought‐limited vegetative productivity. Spatiotemporal shifts in mesic abundance were apparent given biome‐wide climatic trends that reduced precipitation below three‐quarters of normal in 20% of years. Drought sensitivity structured grouse populations wherein landscapes with the greatest uncertainty in mesic abundance and distribution supported the fewest grouse. Privately owned lands encompassed 40% of sage‐grouse range, but contained a disproportional 68% of mesic resources. Regional drought sensitivity identified herein acted as ecological minimums to influence differences in landscape carrying capacity across sage‐grouse range. Our model depictions likely reflect a new normal in water scarcity that could compound impacts of demographic bottlenecks in Great Basin and Great Plains. We conclude that long‐term population maintenance depends on a diversity of drought resistant mesic resources that offset climate driven variability in vegetative productivity. We recommend a holistic public–private lands approach to mesic restoration to offset a deepening risk of water scarcity. Predictions of intensifying water scarcity raises concerns over new demographic bottlenecks impacting sage‐grouse populations in drought sensitive landscapes. We estimate biome‐wide mesic resource productivity from 1984 to 2016 using remote sensing to identify patterns of food availability influencing selective pressures on sage‐grouse. Spatiotemporal shifts in mesic abundance were apparent given biome‐wide climatic trends that reduced precipitation below three quarters of normal in 20% of years. Drought sensitivity structured grouse populations wherein landscapes with the greatest uncertainty in mesic abundance and distribution supported the fewest grouse. We conclude that long‐term population maintenance depends on a diversity of drought resistant mesic resources that offset climate driven variability in vegetative productivity. [ABSTRACT FROM AUTHOR]

Highlights • We used OBIA to map conifers at a 1-m2 resolution across Nevada and California. • Accuracy assessment from reference imagery revealed overall accuracy of 86.38%. • Ground referenced accuracy of conifer classification was 87%. • Our products improve upon and complement existing conifer maps. • Maps aid multi-scale grouse and conifer management across much of the Great Basin. Abstract Distributional expansion and infill of pinyon (Pinus monophylla) and juniper (Juniperus osteosperma, J. occidentalis) trees (hereinafter, "pinyon-juniper") into sagebrush ecosystems alters the ecological function and economic viability of these ecosystems and represents a major contemporary challenge facing land and wildlife managers. Therefore, accurate and high-resolution maps of pinyon-juniper distribution and abundance across broad geographic extents would facilitate science that quantifies ecological effects of pinyon-juniper expansion and help guide land management decisions that better target areas for pinyon-juniper treatment projects. We mapped conifers at a high (1- m2; i.e., 1 × 1-m) resolution across the majority of Nevada and northeastern California. We used digital orthophoto quad tiles from National Agriculture Imagery Program (USDA, 2013) to classify conifers using automated feature extraction (AFE) with the program Feature Analyst™ (Overwatch, 2013). Overall accuracy was >86% across all mapped areas for ground referencing methods. We provide five sets of full-extent maps for land managers: (1) a shapefile representing accuracy results linked to mapping subunits; (2) binary rasters representing conifer presence or absence at a 1-m2 resolution; (3) a 900-m2 resolution raster representing percentages of conifer canopy cover within each cell; (4) 1-m2 resolution canopy cover classification rasters derived from a 50-m radius moving window analysis; and (5) an example map derived from our canopy cover product that prioritizes pinyon-juniper treatment by significance to sage-grouse habitat improvement. Importantly, the canopy cover maps were developed to allow user-specified flexibility based on their own objectives (i.e., develop phases of expansion). These products improve upon or complement existing conifer maps for the Western United States and will help facilitate habitat management and sagebrush ecosystem restoration through an accurate understanding of conifer distribution and abundance at multiple spatial scales. [ABSTRACT FROM AUTHOR]

Energy development and its associated infrastructure, including power lines, may influence wildlife population dynamics through effects on survival, reproduction, and movements of individuals. These infrastructure impacts may be direct or indirect, the former occurring when development acts directly as an agent of mortality (e.g., collision) and the latter when impacts occur as a by‐product of other processes that are altered by infrastructure presence. Functional or numerical responses by predators to power‐line corridors are indirect impacts that may suppress demographic rates for certain species, and perceived predation risk may affect animal behaviors such as habitat selection. Greater sage‐grouse (Centrocercus urophasianus) are a species of conservation concern across western North America that may be affected by power lines. Previous studies, however, have not provided evidence for causal mechanisms influencing demographic rates. Our primary objective was to assess the influence of power lines on multiple sage‐grouse vital rates, greater sage‐grouse habitat selection, and ultimately greater sage‐grouse population dynamics. We used demographic and behavioral data for greater sage‐grouse collected from 2003 to 2012 in central Nevada, USA, accounting for sources of underlying environmental heterogeneity. We also concurrently monitored populations of common ravens (Corvus corax), a primary predator of sage‐grouse nests and young. We focused primarily on a single 345 kV transmission line that was constructed at the beginning of our study; however, we also determined if similar patterns were associated with other nearby, preexisting power lines. We found that numerous behaviors (e.g., nest‐site selection, brood‐site selection) and demographic rates (e.g., nest survival, recruitment, and population growth) were affected by power lines, and that these negative effects were predominantly explained by temporal variation in the relative abundance of common ravens. Specifically, in years of high common raven abundance, avoidance of the transmission line was extended farther from the line, re‐nesting propensity was reduced, and nest survival was lower near the transmission line relative to areas more distant from the transmission line. Additionally, we found that before and immediately after construction of the transmission line, habitats near the footprint of the transmission line were generally more productive (e.g., greater reproductive success and population growth) than areas farther from the transmission line. However, multiple demographic rates (i.e., pre‐fledging chick survival, annual male survival, per capita recruitment, and population growth) for groups of individuals that used habitats near the transmission line declined to a greater extent than for individuals using habitats more distant in the years following construction of the transmission line. These decreases were correlated with an increase in common raven abundance. The geographical extent to which power lines negatively influence greater sage‐grouse demographic processes was thus contingent on local raven abundance and behavior. In this system, we found that effects of power lines, depending on the behavior or demographic rate, extended 2.5–12.5 km, which exceeds current recommendations for the placement of structures in areas around sage‐grouse leks. Nests located 12.5 km from the transmission line had 0.06 to 0.14 higher probabilities of hatching in years of average to high levels of raven abundance, relative to nests located within 1 km of the transmission line. Similarly, leks located 5 km from the transmission line had 0.02 to 0.16 higher rates of population growth (λ) in years of average to high levels of raven abundance, relative to leks located within 1 km of the transmission line. Our finding that negative impacts of the transmission line were associated with common raven abundance suggest that management actions that decouple this association between common raven abundance and power lines may reduce the negative indirect impacts of power lines on greater sage‐grouse population dynamics. However, because the removal of common ravens or the use of perch deterrents on power lines has not been demonstrated to be consistently effective in reducing common raven predation rates on greater sage‐grouse nests, we recommend preferential treatment to mitigation strategies that reduce the number of elevated structures placed within 10 km of critical greater sage‐grouse habitat. © 2018 The Wildlife Society. Positive associations between common raven abundance and power lines resulted in reduced use of, and reproductive success in, habitat near power lines for greater sage‐grouse in central Nevada. Management actions that effectively decouple the association between common raven abundance and power lines may reduce the negative indirect impacts of power lines on greater sage‐grouse population dynamics. [ABSTRACT FROM AUTHOR]

Abstract: A comprehensive understanding of wildlife habitat suitability requires landscape‐scale assessments that provide the framework for subsequent integration with local‐scale relationships. To elucidate the functional role of habitat characteristics at large scales it is necessary to understand how abundance is related to important landscape characteristics. We estimated male greater sage‐grouse Centrocercus urophasianus abundance on leks relative to sagebrush availability, landscape connectivity and anthropogenic infrastructure densities within landscapes surrounding leks from 2006 to 2013 using binomial N‐mixture models. We focused on Wyoming, as the state will play a critical role in the long‐term persistence of greater sage‐grouse due to its relatively robust populations, widespread sagebrush habitats and innovative, large‐scale conservation approaches. Landscapes associated with higher abundance of males on leks were characterized as highly connected, sagebrush‐dominated areas with limited energy development. These modeled relationships were used to evaluate spatial and temporal changes in the landscape‐scale integrity of areas supporting the majority of the greater sage‐grouse populations in Wyoming (i.e. core areas). By assessing relative changes in abundance over time, our models indicated that most of the habitat within core areas (86%) exhibited landscape conditions conducive to supporting medium or large greater sage‐grouse populations that were stable or increasing through time. Larger populations were associated with larger, more centrally located core areas. Conversely, core areas supporting relatively small or declining populations were located along range margins in the eastern portion of the state. The landscape‐scale habitat relationships we developed can be used in combination with local‐scale assessments to generate a more complete picture of greater sage‐grouse habitat suitability. [ABSTRACT FROM AUTHOR]

Abstract: Managers require quantitative yet tractable tools that identify areas for restoration yielding effective benefits for targeted wildlife species and the ecosystems they inhabit. As a contemporary example of high national significance for conservation, the persistence of Greater Sage‐grouse (Centrocercus urophasianus) in the Great Basin is compromised by strongly interacting stressors of conifer expansion, annual grass invasion, and more frequent wildfires occurring in sagebrush ecosystems. Associated restoration treatments to a sagebrush‐dominated state are often costly and may yield relatively little ecological benefit to sage‐grouse if implemented without estimating how Sage‐grouse may respond to treatments, or do not consider underlying processes influencing sagebrush ecosystem resilience to disturbance and resistance to invasive species. Here, we describe example applications of a spatially explicit conservation planning tool (CPT) to inform prioritization of: (1) removal of conifers (i.e., pinyon‐juniper); and (2) wildfire restoration aimed at improving habitat conditions for the Bi‐State Distinct Population Segment of Sage‐grouse along the California–Nevada state line. The CPT measures ecological benefits to sage‐grouse for a given management action through a composite index comprised of resource selection functions and estimates of abundance and space use. For pinyon‐juniper removal, we simulated changes in land‐cover composition following the removal of sparse trees with intact understories, and ranked treatments on the basis of changes in ecological benefits per dollar‐unit of cost. For wildfire restoration, we formulated a conditional model to simulate scenarios for land cover changes (e.g., sagebrush to annual grass) given estimated fire severity and underlying ecosystem processes influencing resilience to disturbance and resistance to invasion by annual grasses. For both applications, we compared CPT rankings to land cover changes along with sagebrush resistance and resilience metrics. Model results demonstrated how the CPT can be an important step in identifying management projects that yield the highest quantifiable benefit to Sage‐grouse while avoiding costly misallocation of resources, and highlight the importance of considering changes in sage‐grouse ecological response and factors influencing sagebrush ecosystem resilience to disturbance and resistance to invasion. This unique framework can be adopted to help inform other management questions aimed at improving habitat for other species across sagebrush and other ecosystems. [ABSTRACT FROM AUTHOR]

• Scoping potential vegetation and habitat benefits can improve restoration success. • Simulation models provide information on likely outcomes, aiding decision-making. • Post-fire restoration actions cannot keep pace with wildfire in sagebrush systems. • Sagebrush revegetation can help, but only on small, local scales after decades pass. • Integrated approaches that consider vegetation and wildlife response are critical. Wildfires are increasingly modifying wildlife habitat in the western United States and managers need ways to scope the pace and degree to which post-fire restoration actions can re-create habitat in dynamic landscapes. We developed a spatially explicit state-transition simulation model (STSM) to project post-fire revegetation and the potential for sage-grouse habitat restoration in sagebrush ecosystems. The model included annual fires, annual grass invasion, conifer encroachment, and projected annual vegetation growth caused by natural regeneration as well as sagebrush seeding and planting. We cross-referenced resulting vegetation maps with greater sage-grouse (Centrocercus urophasianus) habitat needs and evaluated trajectories of potential habitat at three Priority Areas for Conservation in the Great Basin. We compared outcomes among different types of revegetation actions (natural regeneration, seeding, planting), treatment durations, and treatment area sizes. In all scenarios, sagebrush cover was generally insufficient to meet sage-grouse needs for at least a decade post-fire, and the best habitat classes declined or remained at low proportions of landscapes for >50 years post-fire. Under current fire patterns, the pace of habitat restoration is likely to lag behind losses from wildfires. Our results indicate additional efforts beyond sagebrush revegetation actions (e.g., fire suppression, invasive grass treatment) will likely be necessary to maintain and restore areas to meet sage-grouse habitat needs in burned landscapes. Our results also underscore the need for broad-scale habitat restoration strategies that expand the ability to reestablish sagebrush in large, burned areas, as well as strategies for defining which areas should be prioritized for revegetation within the biome. Our landscape models and resulting vegetation maps can be integrated with other restoration prioritization or wildlife monitoring tools that support land manager decision-making. By gauging potential benefits of restoration decisions, our approach can provide information to aid choices on where to invest time, money, and effort and how best to mitigate losses and plan long-term restoration and recovery for landscapes across the sagebrush biome. [Display omitted] [ABSTRACT FROM AUTHOR]

Escalated wildfire activity within the western U.S. has widespread societal impacts and long-term consequences for the imperiled sagebrush (Artemisia spp.) biome. Shifts from historical fire regimes and the interplay between frequent disturbance and invasive annual grasses may initiate permanent state transitions as wildfire frequency outpaces sagebrush communities' innate capacity to recover. Therefore, wildfire management is at the core of conservation plans for sagebrush ecosystems, especially critical habitat for species of conservation concern such as the greater sage-grouse (Centrocercus urophasianus ; hereafter sage-grouse). Fuel breaks help facilitate wildfire suppression by modifying behavior through fuels modification and allowing safe access points for containment by firefighters. The Bureau of Land Management has proposed to roughly double the existing fuel break network in the western U.S., centered on the Great Basin. To our knowledge, no broad-scale examination of fuel break effectiveness or the environmental conditions under which fuel breaks are expected to be most effective has been conducted. We performed a retrospective assessment of probability of fuel break contributing to wildfire containment on recorded wildfire and fuel break interactions from 1985 to 2018 within the western U.S. We characterized environmental, fuels, and weather conditions within 500 m of wildfire contact, and within 5 km of the approaching wildfire. We used a binomial mixed model within a Bayesian framework to identify relationships between these variables and fuel break success. Fuel breaks were least successful in areas classified as having low resilience to disturbance and low resistance to invasion, in areas composed of primarily woody fuels, and when operating in high temperature and low precipitation conditions. Fuel breaks were most effective in areas where fine fuels dominated and in areas that were readily accessible. Maintenance history and fuel break type also contributed to the probability of containment. Overall results indicate a complex and sometimes paradoxical relationship between landscape characteristics that promote wildfire spread and those that impact fuel break effectiveness. Finally, we developed predictive maps of fuel break effectiveness by fuel break type to further elucidate these complex relationships and to inform urgently needed fuel break placement and maintenance priorities across the sagebrush biome. [Display omitted] • We examined fuel break success from 1985 to 2018 across the western U.S. • Increased temperature, shrub cover, and slope decreased fuel break success. • Fuel breaks were less successful in areas less resilient to disturbance. • Ease of access to fuel breaks improved their probability of success. • We developed predictive maps of fuel break effectiveness by type and soil class. [ABSTRACT FROM AUTHOR]