Effectiveness of Wyoming's Sage-Grouse Core Areas: Influences on Energy Development and Male Lek Attendance

Composite estimation to combine spatially overlapping environmental monitoring surveys

Long-term environmental monitoring surveys are designed to achieve a desired precision (measured by variance) of resource conditions based on natural variability information. Over time, increases in resource variability and in data use to address issues focused on small areas with limited sample sizes require bolstering of attainable precision. It is often prohibitive to do this by increasing sampling effort. In cases with spatially overlapping monitoring surveys, composite estimation offers a statistical way to obtain a precision-weighted combination of survey estimates to provide improved population estimates (more accurate) with improved precisions (lower variances). We present a composite estimator for overlapping surveys, a summary of compositing procedures, and a case study to illustrate the procedures and benefits of composite estimation. The study uses the two terrestrial monitoring surveys administered by the Bureau of Land Management (BLM) that entirely overlap. Using 2015-18 data and 13 land-health indicators, we obtained and compared survey and composite indicator estimates of percent area meeting land-health standards for sagebrush communities in Wyoming's Greater Sage-Grouse (Centrocercus urophasianus) Core and NonCore conservation areas on BLM-managed lands. We statistically assessed differences in indicator estimates between the conservation areas using composite estimates and estimates of the two surveys individually. We found composite variance to be about six to 24 units lower than 37% of the survey variances and composite estimates to differ by about six to 10 percentage points from six survey estimates. The composite improvements resulted in finding 11 indicators to statistically differ (p <0.05) between the conservation areas compared to only six and seven indicators for the individual surveys. Overall, we found composite estimation to be an efficient and useful option for improving environmental monitoring information where two surveys entirely overlap and suggest how this estimation method could be beneficial where environmental surveys partially overlap and in small area applications.

Separating Proactive Conservation from Species Listing Decisions

Proactive Conservation is a paradigm of natural resource management in the United States that encourages voluntary, collaborative efforts to restore species before they need to be protected through government regulations. This paradigm is widely used to conserve at-risk species today, and when used in conjunction with the Policy for Evaluation of Conservation Efforts (PECE), it allows for successful conservation actions to preclude listing of species under the Endangered Species Act (ESA). Despite the popularity of this paradigm, and recent flagship examples of its use (e.g., greater sage grouse, Centrocercus urophasianus), critical assessments of the outcomes of Proactive Conservation are lacking from the standpoint of species status and recovery metrics. Here, we provide such an evaluation, using the New England cottontail (Sylvilagus transitionalis), heralded as a success of Proactive Conservation efforts in the northeastern United States, as a case study. We review the history and current status of the species, based on the state of the science, in the context of the Conservation Initiative, and the 2015 PECE decision not to the list the species under the ESA. In addition to the impacts of the PECE decision on the New England cottontail conservation specifically, our review also evaluates the benefits and limits of the Proactive Conservation paradigm more broadly, and we make recommendations for its role in relation to ESA implementation for the future of at-risk species management. We find that the status and assurances for recovery under the PECE policy, presented at the time of the New England cottontail listing decision, were overly optimistic, and the status of the species has worsened in subsequent years. We suggest that use of PECE to avoid listing may occur because of the perception of the ESA as a punitive law and a misconception that it is a failure, although very few listed species have gone extinct. Redefining recovery to decouple it from delisting and instead link it to probability of persistence under recommended conservation measures would remove some of the stigma of listing, and it would strengthen the role of Species Status Assessments in endangered species conservation.

Quantifying habitat loss and modification from recent expansion of energy infrastructure in an isolated, peripheral greater sage-grouse population

New technologies and increasing energy demand have contributed to rapid expansion of unconventional oil and gas development in the U.S. in the past two decades. Quantifying the effects of energy infrastructure on land cover and wildlife habitat is essential for informing land-use policy, developing wildlife conservation strategies, and projecting impacts of future development. The greater sage-grouse (Centrocercus urophasianus; GrSG) is a species of concern in sagebrush ecosystems of the western U.S. and Canada and the focus of widespread conservation and management efforts. Increasing energy development within GrSG range has prompted the need to quantify and predict impacts of energy infrastructure on their habitat and populations. We mapped the annual distribution, surface type, and activity level of energy and non-energy infrastructure in the Parachute-Piceance-Roan (PPR), a small, peripheral greater sage-grouse population in Colorado with expanding oil and gas development, from 2005 to 2015. During that time, the footprint of energy infrastructure more than doubled to 3,275 ha (+108.6%), including 195 new well pads, 930 ha of new pipelines, and 230 km of new roads. In contrast, non-energy infrastructure decreased to 532 ha (-8.3%). The majority of energy infrastructure present each year (77-84%) was supporting infrastructure (i.e. facilities, roads, pipelines) rather than well pads, with an average of 2.24 ± 0.52 SE ha of supporting infrastructure per ha of well pad. Pipelines comprised 74-80% of reclaimed surface and roads comprised 54-69% of disturbed surface across years. By 2015, anthropogenic infrastructure covered 2.70% of occupied range and 2.93% of GrSG habitat, and energy infrastructure covered 2.50% and 10.79% of two priority habitat management area zones in the PPR. Three land cover classes most affected by energy infrastructure were also those strongly selected by GrSG. Topographic constraints appear to concentrate energy infrastructure in areas with gentler topography that also have the highest GrSG use. Together, these patterns suggest that future energy development will cause substantial additional loss and modification of GrSG habitat in the PPR. Our findings are valuable for assessing surface disturbance caps for land-use management and projections of energy infrastructure effects on wildlife habitat in this and other expanding oil and gas fields.

Local and population-level responses of Greater sage-grouse to oil and gas development and climatic variation in Wyoming

BACKGROUND

Spatial scale is important when studying ecological processes. The Greater sage-grouse (Centrocercus urophasianus) is a large sexually dimorphic tetraonid that is endemic to the sagebrush biome of western North America. The impacts of oil and gas (OAG) development at individual leks has been well-documented. However, no previous studies have quantified the population-level response.

METHODS

Hierarchical models were used to estimate the effects of the areal disturbance due to well pads as well as climatic variation on individual lek counts and Greater sage-grouse populations (management units) over 32 years. The lek counts were analyzed using generalized linear mixed models while the management units were analyzed using Gompertz population dynamic models. The models were fitted using frequentist and Bayesian methods. An information-theoretic approach was used to identify the most important spatial scale and time lags. The relative importance of OAG and climate at the local and population-level scales was assessed using information-theoretic (Akaike's weights) and estimation (effect size) statistics.

RESULTS

At the local scale, OAG was an important negative predictor of the lek count. At the population scale, there was only weak support for OAG as a predictor of density changes but the estimated impacts on the long-term carrying capacity were consistent with summation of the local impacts. Regional climatic variation, as indexed by the Pacific Decadal Oscillation, was an important positive predictor of density changes at both the local and population level (particularly in the most recent part of the time series).

CONCLUSIONS

Additional studies to reduce the uncertainty in the range of possible effects of OAG at the population scale are required. Wildlife agencies need to account for the effects of regional climatic variation when managing sage-grouse populations.

Probability of lek collapse is lower inside sage-grouse Core Areas: Effectiveness of conservation policy for a landscape species

Greater sage-grouse (Centrocercus urophasianus) occupy sagebrush (Artemisia spp.) habitats in 11 western states and 2 Canadian provinces. In September 2015, the U.S. Fish and Wildlife Service announced the listing status for sage-grouse had changed from warranted but precluded to not warranted. The primary reason cited for this change of status was that the enactment of new regulatory mechanisms was sufficient to protect sage-grouse populations. One such plan is the 2008, Wyoming Sage Grouse Executive Order (SGEO), enacted by Governor Freudenthal. The SGEO identifies “Core Areas” that are to be protected by keeping them relatively free from further energy development and limiting other forms of anthropogenic disturbances near active sage-grouse leks. Using the Wyoming Game and Fish Department’s sage-grouse lek count database and the Wyoming Oil and Gas Conservation Commission database of oil and gas well locations, we investigated the effectiveness of Wyoming’s Core Areas, specifically: 1) how well Core Areas encompass the distribution of sage-grouse in Wyoming, 2) whether Core Area leks have a reduced probability of lek collapse, and 3) what, if any, edge effects intensification of oil and gas development adjacent to Core Areas may be having on Core Area populations.

Core Areas contained 77% of male sage-grouse attending leks and 64% of active leks. Using Bayesian binomial probability analysis, we found an average 10.9% probability of lek collapse in Core Areas and an average 20.4% probability of lek collapse outside Core Areas. Using linear regression, we found development density outside Core Areas was related to the probability of lek collapse inside Core Areas. Specifically, probability of collapse among leks >4.83 km from inside Core Area boundaries was significantly related to well density within 1.61 km (1-mi) and 4.83 km (3-mi) outside of Core Area boundaries. Collectively, these data suggest that the Wyoming Core Area Strategy has benefited sage-grouse and sage-grouse habitat conservation; however, additional guidelines limiting development densities adjacent to Core Areas may be necessary to effectively protect Core Area populations.