Active Leks Research Articles

A regionally varying habitat model to inform management for greater sage-grouse persistence across their range

Identifying habitat needs for species with large distributions is challenging because species-habitat associations may vary across scales and regions (spatial nonstationarity). Furthermore, management efforts often cross jurisdictional boundaries, complicating the development of cohesive conservation strategies among management entities. The greater sage-grouse (Centrocercus urophasianus) is a rapidly declining species that spans 11 U.S. states and responds to habitat conditions across a wide range of spatial scales and regions. Allowing for regional variance in species-habitat associations and suitability predictions could systematically identify important habitats at levels relevant to management. We collaboratively developed a model with Bureau of Land Management (BLM) biologists that: (1) evaluated the scale of effect for different environmental covariates; (2) accounted for regional differences in population-level responses; and (3) predicted probabilities of persistence across the U.S. occupied range. We modeled range-wide lek persistence data (6615 communal breeding sites classified as active or inactive) as a function of environmental covariates. Environmental covariates included sagebrush cover, pinyon-juniper cover, topography, precipitation, point and line disturbance densities, and landscape configuration metrics. Our model treated habitat assessment areas – regionally delineated by BLM biologists – as random intercepts and slopes that allowed for geographic variation in species-habitat associations and predicted probabilities of lek persistence. Our final model indicated support for 12 environmental covariates predicting lek persistence at scales extending between 1- to 15-km radii from lek centers, and a covariate measuring distance to the occupied range boundary. Five of these covariates showed significant regionally varying responses: sagebrush clumpiness (a measure of habitat aggregation), pinyon-juniper cover, point disturbance of anthropogenic features such as energy infrastructure and communication towers, elevation, and a topographic index associated with mesic habitats. This spatial nonstationarity indicates unitary range-wide recommendations, or rules-of-thumb with respect to their effects on lek persistence, may be problematic for these environmental conditions. For covariates that did not include random slopes, and which were potentially amenable to management actions, we found that leks were predicted to become extirpated when sagebrush cover fell below 9.6 % (summarized at the 3.2-km radius extent), and the proportion of classified sagebrush habitat fell below 0.7 (1-km). We produced a continuous predictive probability surface of lek persistence which we binned based on model sensitivity thresholds to produce habitat quality categories. The highest quality habitat (capturing 50 % of active leks) covered 25.5 % of the occupied range, while the combined lowest through highest quality habitats (capturing 95 % of active leks) covered 65.0 %. Accommodating regional environmental differences in models that are relevant to habitat management planning will help ensure their applicability to targeted goals. Continuous collaboration between modelers and land managers early in the modeling process increases the likelihood of this outcome.

Comparing Methods of Defining Priority Areas for Greater Sage-Grouse

Wildlife managers delineate priority areas for species to define critical habitat and to prioritize management efforts. Each method used to identify priority areas involves data that can be unavailable or expensive to obtain. Therefore, it is of interest to compare spatial efficiency between methods used for defining priority areas. We compared priority areas created using different methods and data types. We used resource selection function (RSF) models to predict areas of high use and generated a map depicting ≥ 90% predicted use in three seasons; it was 1,143 km2, encompassed 91% of nests, 68% of summer locations, and 71% of winter locations. We compared the RSF priority area to priority areas developed using two alternative methods: (1) modified conservation buffer, and (2) utilization distribution (UD) models. The modified conservation buffer method was used by South Dakota Game, Fish and Parks in 2014 to delineate a priority area by buffering active lek sites by 6.4 km, including connectivity corridors defined via expert opinion, and known high use areas. The priority area generated by the modified conservation buffer method was 3,977 km2, encompassed 95% of nest locations, 92% of spring/summer locations, and 99% of winter locations. Lastly, we developed a priority area using combined UDs from radio-tracking data gathered during spring/summer, and winter and included a lek buffer encompassing 90% of known nest-sites. This priority area was 3,498 km2, encompassed 99% of nests, 98% of spring/summer locations, and 97% of winter locations. The priority area generated by RSF models was the smallest and encompassed the least number of nests and spring/summer and winter locations but was considered the most spatially efficient; it had the most nests, spring/summer locations, and winter locations per 100 km2. The UD and modified conservation buffer methods created priority areas that were similar in size and spatial efficiency. The modified conservation buffer method encompassed >90% of known sage-grouse locations and nests, indicating that in the absence of detailed movement data and more sophisticated modeling, the method can be sufficient in developing an adequate priority area.

Changes in hunting season regulations (1870s-2019) reduce harvest exposure on greater and Gunnison sage-grouse.

Hunter harvest is a potential factor contributing to population declines of sage-grouse (Centrocercus spp.). As a result, wildlife agencies throughout western North America have set increasingly more conservative harvest regulations over the past 25 years to reduce or eliminate hunter success and concomitant numbers of harvested greater (C. urophasianus) and Gunnison (C. minimus) sage-grouse. Sage-grouse hunting has varied widely over time and space, which has made a comprehensive summary of hunting management challenging. We compiled data on harvest regulations among 11 western U.S. states and 2 Canadian provinces from 1870–2019 to create a timeline representative of hunting regulations. We compared annual harvest boundaries and area-weighted average hunting regulations, 1995–2018, relative to administrative boundaries and areas of high probability of sage-grouse occupation. We also summarized estimated numbers of birds harvested and hunters afield, 1995–2018, across both species’ ranges. From 1995–2018, there was a 30% reduction in administrative harvest boundaries across the greater sage-grouse range compared to a 16.6% reduction in area open to harvest within 8 km from active leks. Temporary closures occurred in response to wildfires, disease outbreaks, low population numbers, and two research projects; whereas, permanent closures primarily occurred in small populations and areas on the periphery of the species distribution. Similarly, area-weighted possession limits and season length for greater sage-grouse decreased 52.6% and 61.0%, respectively, while season start date stayed relatively stable (mean start date ~259 [mid-September]). In contrast, hunting of the now federally-threatened Gunnison sage-grouse ended after 1999. While restrictions in harvest regulations were large in area, closures near areas of high greater sage-grouse occupancy were relatively smaller with the same trend for Gunnison sage-grouse until hunting ceased. For greater sage-grouse, most states reduced bag and possession limits and appeared to adhere to recommendations for later and shorter hunting seasons, reducing potential for additive mortality.

Male Aggregation in Dwarf Tyrant-Manakins and What It Tells Us about the Origin of Leks.

Despite considerable research on lek-breeding birds, many aspects of the evolution of the lek social system, including the origin of male aggregation, remain unresolved. Originally, clusters may have formed passively as a by-product of independent but concurrent responses by males to some external stimulus (e.g., a concentration of display sites, prominent food source, or a travel corridor commonly used by females) that drew them at a particular time to a site where they might increase their probabilities of encountering females. In contrast, male aggregation may have been active, with a male purposely seeking to associate with another male (or males) because proximity to that male allowed him to enhance his own reproductive success by improving his ability to attract females (i.e., learning from his associate) or to intercept females attracted to that male. To identify factors important in the formation of male aggregations, I studied these alternatives in the Dwarf Tyrant-Manakin (Tyranneutes stolzmanni), a species in which some breeding males occupy solitary courts where they attempt to attract females for reproduction, whereas other males occupy courts clustered into leks, where they interact to attract females. I compared habitat characteristics and resource availability at courts of grouped and solitary males as well as certain traits of the males in an attempt to distinguish between passive or active lek formation in this species. Little evidence suggests that Dwarf Tyrant-Manakins are passively clustered as a result of common attraction to or use of a limited or unevenly distributed resource. Several observations suggest the contrary. Evidence for the active aggregation of males is more promising, suggesting that males may associate with other males on the basis of their vocal behavior. The issue is confounded, however, by the observation that male call behavior appears to change with a change in social status. A definitive answer for T. stolzmanni will require additional analyses of vocal behavior as well as of the characteristics of the vocalizations themselves. Finally, the behavior and social organization of this species may reflect characteristics of the ancestral manakin line that gave rise to both the Tyrant and Core clades of modern manakins.

Aural and Visual Detection of Greater Sage‐Grouse Leks: Implications for Population Trend Estimates

ABSTRACTCounts of greater sage‐grouse (Centrocercus urophasianus) at leks have been used in harvest management, Endangered Species Act listing decisions, and land management policies for over half a century. Lek count sampling methods focus on counting male sage‐grouse at known leks, primarily those observed visually from roads or vantage points, but leks are likely missed that are unknown prior to the survey and are difficult to detect while driving between known lek sites. One way to ameliorate this shortfall may be to conduct short point‐count surveys at multiple stops along lek‐survey routes or while driving between lek counts, thereby detecting newly established or unknown leks. To evaluate the feasibility of this approach, we estimated aural and visual detection probability of active sage‐grouse leks during 1‐minute point‐count surveys at known distances and examined the effects of environmental factors on aural lek detection in southern Idaho, USA, 2016–2017. Our results demonstrate that field observers can aurally detect sage‐grouse leks at approximately 3 times greater distances compared to detecting leks visually. The probability of hearing an active lek was highest near the peak of male and female attendance (8 Apr), within an hour of sunrise, on relatively calm and cold days, when the observer was at a higher elevation relative to the lek, and during conditions with no background noise. Detection probability declined with distance and the probability of aural detection was 0.59 at 1 km from a lek when other variables were held at their means. Hence, conducting ≥3 1‐minute surveys along a lek route would be expected to detect ≥93% of all leks within 1.5 km of each survey under the average environmental conditions in our study. Our results suggest that surveys could greatly improve detection of unknown or newly established leks and can facilitate a more accurate assessment of sage‐grouse population trends through lek counts. Moreover, our results demonstrate how environmental factors influence the detection of leks during surveys, and therefore which variables should be considered for inclusion in any future revisions of lek count protocols or in analyses of lek count data. © 2021 The Wildlife Society.

Free-roaming horses disrupt greater sage-grouse lekking activity in the Great Basin

Greater Sage-Grouse (Centrocercus urophasianus; hereafter, sage-grouse) and free-roaming horses (Equus caballus) co-occur within large portions of sagebrush ecosystems within the Great Basin of western North America. In recent decades, sage-grouse populations have declined substantially while concomitant free-roaming horse populations have increased drastically. Although multiple studies have reported free-roaming horses adversely impacting native ungulate species, direct interactions between free-roaming horses and sage-grouse have not been documented previously. We compiled sage-grouse lek count data and associated ungulate observations during spring of 2010 and 2013–2018. We used Bayesian multinomial logistic models to examine the response of breeding male sage-grouse to the presence of native (i.e. mule deer, pronghorn) and non-native (i.e. cattle, free-roaming horses) ungulates on active sage-grouse leks (traditional breeding grounds). We found sage-grouse were approximately five times more likely to be present on active leks concurrent with native ungulates compared to non-native ungulates. Of the four different ungulate species, sage-grouse were least likely to be at active leks when free-roaming horses were present. Our results indicate that free-roaming horse presence at lek sites negatively influences sage-grouse lekking activity. Because sage-grouse population growth is sensitive to breeding success, disruption of leks by free-roaming horses could reduce breeding opportunities and limit breeding areas within sage-grouse habitat.

The effects of electric power lines on the breeding ecology of greater sage-grouse.

Anthropogenic infrastructure can negatively affect wildlife through direct mortality and/or displacement behaviors. Some tetranoids (grouse spp.) species are particularly vulnerable to tall anthropogenic structures because they evolved in ecosystems void of vertical structures. In western North America, electric power transmission and distribution lines (power lines) occur in sagebrush (Artemisia spp.) landscapes within the range of the greater sage-grouse (Centrocercus urophasianus; sage-grouse). The U.S. Fish and Wildlife Service recommended using buffer zones near leks to mitigate the potential impacts of power lines on sage-grouse. However, recommended buffer distances are inconsistent across state and federal agencies because data are lacking. To address this, we evaluated the effects of power lines on sage-grouse breeding ecology within Utah, portions of southeastern Idaho, and southwestern Wyoming from 1998–2013. Overall, power lines negatively affected lek trends up to a distance of 2.7 and 2.8 km, respectively. Power lines died not affect lek persistence. Female sage-grouse avoided transmission lines during the nesting and brooding seasons at distances up to 1.1 and 0.8 km, respectively. Nest and brood success were negatively affected by transmission lines up to distances of 2.6 and 1.1 km, respectively. Distribution lines did not appear to affect sage-grouse habitat selection or reproductive fitness. Our analyses demonstrated the value of sagebrush cover in mitigating potential power line impacts. Managers can minimize the effects of new transmission power lines by placing them in existing anthropogenic corridors and/or incorporating buffers at least 2.8 km from active leks. Given the uncertainty we observed in our analyses regarding sage-grouse response to distribution lines coupled with their role in providing electric power service directly to individual consumers, we recommend that buffers for these power lines be considered on a case-by-case basis. Micrositing to avoid important habitats and habitat reclamation may reduce the potential impacts of new power line construction.

Are Lek Disturbance Buffers Equitable for All Gunnison Sage-Grouse Populations?

Abstract Lek disturbance buffers can be used to identify areas that provide important seasonal habitat for Gunnison sage grouse Centrocercus minimus (hereafter GUSG), a species with declining or vulnerable populations across their range. Lek disturbance buffers define areas around leks where anthropogenic disturbance is not permitted and have been considered for potential conservation strategies across GUSG habitat. Currently there is minimal information available on the effectiveness of the size of defined lek disturbance buffers. This study focused on two GUSG populations, the smaller Crawford population and a segment of the larger Gunnison Basin population. We utilized global positioning system location data on GUSG to evaluate seasonal use within three lek disturbance buffers, then compared and contrasted results between the two populations. The Crawford GUSG population showed increased movements from breeding season to late brood-rearing season and in winter returned to a usage pattern similar to the breeding season. Comparatively, the western Gunnison Basin GUSG population showed considerable movement throughout the entire year. In addition to these differences, we noted remarkable differences in distance between active leks, home range size, and total daily distance traveled between Crawford and western Gunnison Basin populations. Lek disturbance buffers created using the standard protocol provided varying protection depending on the distance between leks and number of leks. In small populations, the disturbance buffers overlapped each other, thus producing a smaller total lek disturbance buffer area. In addition to adding to the general body of knowledge of a little-studied species, our study had two important findings: 1) the use of empirical cumulative distribution demonstrated considerable differences in lek disturbance buffer use between the Crawford and the western Gunnison Basin populations, and 2) lek disturbance buffers did not provide equal protection for all populations on the basis of their current definition and derivation. We anticipate that land managers will find our results useful and informative when developing land management plans for the conservation of GUSG. Our analysis showed that the variability between populations and species is important for managers to consider when developing conservation strategies, especially for small populations.

Modelling Capercaillie (Tetrao urogallus) lek sites distribution and their limiting factors in a central Norwegian managed forest landscape

Forest management has substantially altered Fennoscandian forests through clear-cutting practices started during the 1950s. Impacts on the natural biodiversity in mature boreal forest have been inevitable. The Capercaillie (Tetrao urogallus) is often regarded as an indicator species for natural old growth forest, displaying on traditional lek sites during spring. In a heterogeneous forest landscape of two adjoining municipalities in central Norway we studied whether forest management or other environmental factors can have influenced the lek distribution. We identified 15 active leks and 12 recently abandoned leks. The maximum entropy distribution modelling (MaxEnt) was used to investigate factors associated with lek distribution at two different scales, where the scale reflecting the lek site areas gave the most adequate result. Active leks were predominantly associated with mature stands of forest. In 65% of the study area the habitat suitability for lekking was most influenced by forest management. Furthermore, the recently abandoned leks were found less frequently in low productive and mature forests than the still active ones, implying that previous leks in productive forest stands may have been lost through logging. Based on our data we have developed models for the predicted distribution and the current limiting factors, showing that altered forest management could improve lek site suitability in large parts of this boreal forest.

Dual‐frame lek surveys for estimating greater sage‐grouse populations

ABSTRACTEffective monitoring programs are important for ensuring proper management of wildlife populations, but they require substantial resources, effort, and funding. For this reason, managers often use indices of animal abundance. However, indices typically rely on untested assumptions and may be unreliable for estimating population size, status, and trend. Therefore, it is important to test the assumptions underlying indices and to evaluate more rigorous methods of population estimation. Counts of males at leks are used as an index to monitor populations of greater sage‐grouse (Centrocercus urophasianus), a species of conservation concern, throughout its range in the western United States and Canada. However, not all leks are known, and wildlife managers typically have no rigorous, quantitative estimates of the number of leks and males in any given population. Therefore, it remains unclear what proportion of leks and males are included in, or excluded from, lek‐based population status assessments, trend analyses, and management decisions. We used dual‐frame surveys, in combination with occupancy analysis to adjust for imperfect detection, to estimate the number of active leks, the number of lekking males, and the proportion of active leks and lekking males counted on annual lek surveys over 3 consecutive breeding seasons in a small, low‐density greater sage‐grouse population in northwestern Colorado, USA. We estimated that annual lek surveys captured an average of 45–74% of active leks and 43–78% of lekking males each year. Our results suggest that many active leks remain unknown and annual counts fail to account for a substantial, but variable, proportion of the number of active leks and lekking males in the population in any given year. Managers need to recognize this potential source of bias in lek‐count data and, if possible, account for it in trend analyses and management efforts. Increased cost likely precludes annual use of dual‐frame lek surveys. However, we recommend using analytical methods that account for imperfect detection, mapping potential lek habitat to improve survey efficiency, and conducting dual‐frame surveys over multiple years to better understand temporal variation in the proportion of active greater sage‐grouse leks and lekking males being counted in specific populations of interest. © 2018 The Wildlife Society.

Weather conditions and date influence male Sage Grouse attendance rates at leks

For lek‐breeding birds, lek attendance can be correlated with mating success. Variability in lek attendance could confound interpretation of male reproductive effort and complicate the use of lek counts as an index to monitor abundance. We assessed the daily probability of male Sage Grouse Centrocercus urophasianus lek attendance and explored implications of attendance on lek counts. We fitted 145 males with global positioning system (GPS) transmitters over 4 years in Carbon County, Wyoming. We evaluated influences of lek size and topography, date, weather, and bird characteristics such as age on daily morning lek attendance. The daily probability of attendance ranged considerably each year, from 0.120 (, 95% CI 0.051–0.259) in 2012 to 0.917 (95% CI 0.844–0.957) in 2013 with peak attendance dates ranging from 8 April (2012) to 11 May (2011). Attendance decreased with increasing precipitation on the observation day. Only 44–79% of lek counts occurred on days without precipitation and with high attendance (i.e. within 0.1 probability of peak predicted attendance). Although lek counts and population abundance, predicted using attendance rates, followed a similar trend, the relationship was not significantly correlated. We provide empirical evidence supporting current lek‐count protocols: managers should avoid counting leks on days with precipitation because attendance is reduced. Although managers sometimes only complete one to two lek counts per year on active leks, completing at least three lek counts as recommended in protocols increases chances for higher male counts and improves the relationship between counts and abundance. Attendance varies annually, making it challenging to use lek counts to assess regional population trends over short time periods unless attendance is accounted for.

Understanding biological effectiveness before scaling up range‐wide restoration investments for Gunnison sage‐grouse

AbstractImperiled species recovery is a high‐stakes endeavor where uncertainty surrounding effectiveness of conservation actions can be an impediment to implementation at necessary scales, especially where habitat restoration is required. Gunnison sage‐grouse (Centrocercus minimus) represents one such species in need of large‐scale habitat restoration. It is a federally threatened sagebrush (Artemisia spp.) obligate bird with a limited range in Colorado and Utah. Threats to recovery of Gunnison sage‐grouse include conifer expansion into sagebrush along with additional habitat loss and degradation attributed to human development and agricultural conversion. Recovery of Gunnison sage‐grouse and other sensitive species can be aided by spatial tools that forecast plausible outcomes of conservation actions. We illustrate this by using a novel framework for predicting outcomes of proactive tree removal and subsequent sagebrush restoration for the Gunnison sage‐grouse. To assess threats on Gunnison sage‐grouse lek presence, we developed a spatially explicit breeding habitat model to compare active lek and random pseudo‐absence locations from 2015. Models identified land cover, climatic, and abiotic variables at landscape‐level scales (0.56 and 4 km) most important for predicting breeding habitat. Our model correctly differentiated between lek and pseudo‐absence locations 94% of the time. All but one of the active leks (n = 94) were in areas with >0.65 probability of lek occurrence. Using this probability value as a threshold, we predicted 15% of the current grouse range as high‐quality breeding habitat. Simulated removal of trees in areas with ≤30% tree canopy cover (0.56‐km scale) increased extent of high‐quality habitat fourfold (59%). Hypothetical restoration of sagebrush cover in the same areas increased habitat quality an additional 11%. Our breeding habitat model indicated that targeted tree removal and sagebrush restoration have potential to improve Gunnison sage‐grouse breeding habitat. While our habitat treatment scenarios were not meant to be prescriptive, they highlight that considerable uplift in Gunnison sage‐grouse breeding habitat may be possible across much of its range with cooperation from multiple stakeholders and illustrates the utility of this approach for predicting biological return on investment.

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.

A generalized integrated population model to estimate greater sage‐grouse population dynamics

AbstractFor species of conservation concern, assessing population dynamics consistently across different populations is of paramount importance to effective conservation and restoration planning. This effort presents a challenge for wide‐ranging species with considerable variation in both abundance and demographic rates. Raw counts of individuals are typically used to assess population trends at broad scales, but the demographic rates that explain changes in population size can only feasibly be measured at local scales. We developed a generalized integrated population model, which combines the strengths of these two data types, for the greater sage‐grouse (Centrocercus urophasianus). We used N‐mixture models to estimate annual abundance from counts of males at breeding leks and constructed a two‐sex, demographic matrix model using published vital rate estimates for male and female sage‐grouse from across their range. We applied the model to 13 years of statewide lek counts for Montana, USA. Then, we applied the model to local, annually varying vital rate estimates and lek count data from a population in the Powder River Basin in Montana and Wyoming. We demonstrate potential for this modeling approach to improve our understanding of sage‐grouse population dynamics in a consistent and robust framework, especially as data quality and quantity increases. We use our results to highlight the need for better data on sex and age ratios, female population size, and the proportion of active leks being monitored each year. While our model was focused on the greater sage‐grouse, this approach could be applied to a variety of sensitive species to compare population dynamics across a species’ range.

Factors affecting female space use in ten populations of prairie chickens

Conservation of wildlife depends on an understanding of the interactions between animal movements and key landscape factors. Habitat requirements of wide‐ranging species often vary spatially, but quantitative assessment of variation among replicated studies at multiple sites is rare. We investigated patterns of space use for 10 populations of two closely related species of prairie grouse: Greater Prairie‐Chickens (Tympanuchus cupido) and Lesser Prairie‐Chickens (T. pallidicinctus). Prairie chickens require large, intact tracts of native grasslands, and are umbrella species for conservation of prairie ecosystems in North America. We used resource utilization functions to investigate space use by female prairie chickens during the 6‐month breeding season from March through August in relation to lek sites, habitat conditions, and anthropogenic development. Our analysis included data from 382 radio‐marked individuals across a major portion of the extant range. Our project is a unique opportunity to study comparative space use of prairie chickens, and we employed standardized methods that facilitated direct comparisons across an ecological gradient of study sites. Median home range size of females varied ~10‐fold across 10 sites (3.6–36.7 km2), and home ranges tended to be larger at sites with higher annual precipitation. Proximity to lek sites was a strong and consistent predictor of space use for female prairie chickens at all 10 sites. The relative importance of other predictors of space use varied among sites, indicating that generalized habitat management guidelines may not be appropriate for these two species. Prairie chickens actively selected for prairie habitats, even at sites where ~90% of the land cover within the study area was prairie. A majority of the females monitored in our study (>95%) had activity centers within 5 km of leks, suggesting that conservation efforts can be effectively concentrated near active lek sites. Our data on female space use suggest that lek surveys of male prairie chickens can indirectly assess habitat suitability for females during the breeding season. Lek monitoring and surveys for new leks provide information on population trends, but can also guide management actions aimed at improving nesting and brood‐rearing habitats.

Rapid decline of an isolated population of the black grouse Tetrao tetrix: the crisis at the southern limit of the range

Over the last century, the numbers and range of black grouse Tetrao tetrix have declined dramatically over most of Europe. The Central-European population is at present divided into small, isolated subpopulations, and Orawa (Carpathians, Poland-Slovakia) was considered until recently to be the most abundant one in the region. In 2002, it was estimated at 146–152 males. Surveys conducted in 2011–2014 showed that only 30–40 males were still present in this region. The total disappearance of leks (13 of 24 known leks have been abandoned) and the decline in overall numbers of males at existing leks (some leks were used by single males only) were recorded. In consequences, the number of lekking males decline by 76 % between 2002 and 2014. The nearest neighbour distance between active leks did not change, but the contraction of the total area used by the population (from 187.3 km2 in 2002 to 71.5 km2 in 2014) was recorded. The disappearance of leks was related to the size of the nearest peat bog; leks located close to small peat bogs were abandoned, while those located close to the larger ones remained active. Along with the decline in the numbers of lekking birds and the shrinkage of the range, a decrease in the size of wintering flocks was noted. This rapid fall over a short period of time in the number of black grouse and in the area used by the region’s largest population is indicative of a real threat of extinction of isolated populations. Rapid extinction risk should be taken into consideration when planning conservation measures applicable to its entire range of distribution.

Diurnal space use and seasonal movement patterns of greater sage-grouse in Northeastern California

Greater sage-grouse (Centrocercus urophasianus) populations have declined throughout their geographic range, are considered a candidate species under the U.S. Endangered Species Act, and are regarded as a species of special concern in California, USA. Demographic parameters have been well-documented for this species, but populations occupying the western periphery of their range have largely remained unstudied. We examined diurnal space use and seasonal movement patterns of greater sage-grouse in northeastern California. We collected 3,072 diurnal locations from 132 greater sage-grouse radiomarked between 2007 and 2009. Greater sage-grouse in our study used large areas and exhibited wide-ranging seasonal movements. Female greater sage-grouse sought suitable nesting habitat within 5 km of a lek; however, of the 27% (n = 20/74) of females nesting >5 km from an occupied lek site, 53% (n = 10/19) nested successfully. This suggests the proportion of nesting females located >5 km from an active lek is important for population viability in northeastern California. Moreover, the annual range of movements indicates that conserving greater sage-grouse habitat within 5 km of active lek sites is insufficient to maintain long-term population persistence. Larger areas of habitat are needed to conserve greater sage-grouse in northeastern California to accommodate seasonal movements, annual variation in habitat requirements, and to maintain connectivity between lek complexes. © 2014 The Wildlife Society.

Comparison of Patterns of Genetic Variation and Demographic History in the Greater Sage-Grouse (Centrocercus urophasianus): Relevance for Conservation

The greater sage-grouse (Centrocercus urophasianus) was once widespread in western North America but its range has contracted by an uncertain degree owing to anthropogenic and natural causes. Concern over population declines has led to its proposed listing as threatened under the U.S. Endangered Species Act. Detailed genetic and demographic analyses of this species throughout its range are available but heretofore have not been compared. Reduced genetic variability is often taken as a proxy for declining populations, but rarely are there quantitative population estimates with which to compare. I compared published mitochondrial DNA (mtDNA) control region sequences, microsatellite allele frequencies at seven loci, and estimates of numbers of males per lek, number of active leks, percent decline in the best population models, and the probability (P) of Ne < 50 in 30 years and P(Ne < 500) in 100 years, at two spatial scales, 45 local population samples and 16 larger aggregates of samples. When excluding the populations from the Columbia Basin, which show little genetic diversity and are statistical outliers, there were no consistent relationships between estimates of genetic variation and demographic trends across the remainder of the range at either spatial scale. A measure of inbreeding derived from microsatellite data was also not related to population trends. Thus, despite habitat reduction and range fragmentation, the greater sage-grouse does not exhibit expected genetic signatures of declining populations. Possibly, the mtDNA and microsatellite data are insufficiently sensitive to detect population declines that have occurred over the span of a half century. Alternatively, only when populations are reduced to the levels seen in the Columbia Basin will genetic effects be seen, suggesting that the bulk of the range of the greater sage-grouse is not currently in genetic peril.

Saving sage-grouse from the trees: A proactive solution to reducing a key threat to a candidate species

Conservation investment in management of at-risk species can be less costly than a delay-and-repair approach implemented after species receive legal protection. The United States Endangered Species Act candidate species designation represents an opportunity to implement proactive management to avoid future listing. Such efforts require substantial investments, and the challenge becomes one of optimization of limited conservation funds to maximize return. Focusing on conifer encroachment threats to greater sage-grouse (Centrocercus urophasianus), we demonstrated an approach that links species demographics with attributes of conservation threats to inform targeting of investments. We mapped conifer stand characteristics using spatial wavelet analysis, and modeled lek activity as a function of conifer-related and additional lek site covariates using random forests. We applied modeling results to identify leks of high management potential and to estimate management costs. Results suggest sage-grouse incur population-level impacts at very low levels of encroachment, and leks were less likely to be active where smaller trees were dispersed. We estimated costs of prevention (treating active leks in jeopardy) and restoration (treating inactive leks with recolonization potential) management across the study area (2.5 millionha) at a total of US$17.5 million, which is within the scope of landscape-level conservation already implemented. An annual investment of US$8.75 million can potentially address encroachment issues near all known Oregon leks within the next decade. Investments in proactive conservation with public and private landowners can increase ecosystem health to benefit species conservation and sustainable land uses, replace top-down regulatory approaches, and prevent conservation reliance of at-risk species.

Combined Effects of Energy Development and Disease on Greater Sage-Grouse

Species of conservation concern are increasingly threatened by multiple, anthropogenic stressors which are outside their evolutionary experience. Greater sage-grouse are highly susceptible to the impacts of two such stressors: oil and gas (energy) development and West Nile virus (WNv). However, the combined effects of these stressors and their potential interactions have not been quantified. We used lek (breeding ground) counts across a landscape encompassing extensive local and regional variation in the intensity of energy development to quantify the effects of energy development on lek counts, in years with widespread WNv outbreaks and in years without widespread outbreaks. We then predicted the effects of well density and WNv outbreak years on sage-grouse in northeast Wyoming. Absent an outbreak year, drilling an undeveloped landscape to a high permitting level (3.1 wells/km2) resulted in a 61% reduction in the total number of males counted in northeast Wyoming (total count). This was similar in magnitude to the 55% total count reduction that resulted from an outbreak year alone. However, energy-associated reductions in the total count resulted from a decrease in the mean count at active leks, whereas outbreak-associated reductions resulted from a near doubling of the lek inactivity rate (proportion of leks with a last count = 0). Lek inactivity quadrupled when 3.1 wells/km2 was combined with an outbreak year, compared to no energy development and no outbreak. Conservation measures should maintain sagebrush landscapes large and intact enough so that leks are not chronically reduced in size due to energy development, and therefore vulnerable to becoming inactive due to additional stressors.