Rapid development of wind energy facilities in the Great Plains of North America has raised concerns regarding their potential negative impact on the nesting ecology of Greater Prairie-Chickens (Tympanuchus cupido pinnatus). We investigated the effects of a pre-existing, 36-turbine wind energy facility on nest site selection and nest survival of Greater Prairie-Chickens in the unfragmented grasslands of the Nebraska Sandhills, USA. In 2013 and 2014, we monitored 91 nests along a 24-km disturbance gradient leading away from the wind energy facility. We found little evidence of an effect of the wind energy facility on Greater Prairie-Chicken nest site selection and nest survival. Instead, we found that the primary drivers of nest site selection and nest survival were related to landscape and habitat factors. Greater Prairie-Chickens avoided nesting near roads, with 74% of Greater Prairie-Chickens selecting nest sites .700 m from roads. Greater Prairie-Chickens selected nest sites with more than twice the visual obstruction and residual standing dead vegetation of random points. Our results suggest that small wind energy facilities, such as the facility in our study, may have little effect on Greater Prairie-Chicken nest site selection and nest survival. We suggest that livestock grazing and other grassland management practices still have the most important regional effects on Great Prairie-Chickens, but we caution future planners of wind energy facilities to account for the potential negative effect of roads on nest site selection.

Biologists and conservation planners are frequently asked to evaluate the spatial effects of anthropogenic disturbance on species of conservation concern. The linear response of a demographic parameter, such as survival or abundance, to the distance-from-disturbance is often used to inform spatial restrictions on development. The linear response, we argue, does not model the most common biological mechanisms that cause changes to demographic parameters, nor does it provide an estimate of a threshold that planners could use to protect species of concern. In the Great Plains of North America, biologists are increasingly concerned about the impact of energy development on populations of four species of grouse. To address this gap in our ability to properly assess distance thresholds, we developed a framework of four response patterns (null, linear, stair step, ramped) to describe the potential effects of a disturbance on biological processes relevant to nesting grouse located along a gradient from the disturbance. We simulated position and survival of grouse nests along a 25-km disturbance gradient to mimic the response to disturbances. We evaluated the relative support for a set of linear and nonlinear models in a known fate analysis of nest survival. Each of the underlying response patterns was detected with an appropriate model in a model selection framework (wAIC  0.61-0.75) when the sample size of nests was high (n  500), and thresholds were identified when present. In a low sample size scenario (n  50 nests) that may be typical of shortterm empirical sampling schemes, the stair step threshold was detected, but the more complex, ramped threshold was not detected. We provide recommendations regarding study design and inference for ecological and policy thresholds, and we encourage researchers to be cautious about the manner in which threshold responses are assessed and described.

Abstract. Recent expansion of the wind energy industry has raised concerns about the potential effects of wind energy facilities on prairie grouse. For example, efforts have been made to evaluate indirect effects on prairie grouse survival, but it is also critical to investigate the underlying mechanisms to direct conservation strategies. The objective of this study was to investigate the indirect effects of a wind energy facility on the survival of female Greater Prairie-Chickens (Tympanuchus cupido pinnatus) and on the occupancy of avian and mammalian predators. Between March and July of 2013 and 2014, we investigated spatial variation in predation risk by sampling occupancy of mammalian and avian predators within 10 km of a wind energy facility constructed in 2005 in Brown County, Nebraska, USA. During the same period, we assessed spatial variation in daily survival of radio-marked females within the same area. We found little evidence that probability of site occupancy (Ψ) of avian predators was lower near the wind energy facility (within 2 km: Ψ = 0.70, 95% CI = 0.22-0.95; beyond 2 km: Ψ = 0.93, 95% CI = 0.02-1.00), suggesting that avian predators did not display local-scale avoidance behavior around wind turbines. Mammalian predators were documented at all of our sample locations, but the capture index for all mammals was lower at sample sites near the wind turbines (P = 0.004). Occupancy of coyotes (Canis latrans), the likely main mammalian predator of adult prairie-chickens in the area, did not vary significantly throughout our study site (within 0.5 km of wind energy facility: Ψ = 0.65, 95% CI = 0.07-0.98; beyond 0.5 km: Ψ = 0.96, 95% CI = 0.04-1.00), although trends were in the direction expected if coyotes were avoiding the wind energy facility. Distance to wind turbine had no effect on daily survival (S D ) of female prairie-chickens (S D = 0.9948, SE = 0.0015). The potential for predators to avoid wind energy facilities, and thus affect predation risk, underscores the complexity of planning to address potential impacts of wind energy as variation in predation risk may have consequences for the population viability of a wide range of species at risk from wind energy development.

Over the last century, increasing human populations and conversion of grassland to agriculture have had severe consequences for numbers of Greater Prairie-Chicken (Tympanuchus cupido). Understanding Greater Prairie-Chicken response to human disturbance, including the effects of anthropogenic noise and landscape modification, is vital for conserving remaining populations because these disturbances are becoming more common in grassland systems. Here, we evaluate the effect of low-frequency noise emitted from a wind energy facility on habitat selection. We used the Normalized Difference Soundscape Index, a ratio of human-generated and biological acoustic components, to determine the impact of the dominant acoustic characteristics of habitat relative to physical landscape features known to influence within–home range habitat selection. Female Greater Prairie-Chickens avoided wooded areas and row crops but showed no selection or avoidance of wind turbines based on the availability of these features across their home range. Although the acoustic environment near the wind energy facility was dominated by anthropogenic noise, our results show that acoustic habitat selection is not evident for this species. In contrast, our work highlights the need to reduce the presence of trees, which have been historically absent from the region, as well as decrease the conversion of grassland to row-crop agriculture. Our findings suggest physical landscape changes surpass altered acoustic environments in mediating Greater Prairie-Chicken habitat selection.