1,482 research outputs found

    Comparison of Conservation Policy Benefits for an Umbrella and Related Sagebrush-Obligate Species

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    Many conservation strategies promote the potential of multiple species benefitting from protection of large areas necessary for the continued viability of 1 species. One prominent strategy in western North America is Wyoming’s Sage-grouse Core Area Policy, which was designed to conserve greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) breeding habitat, but may also serve as an umbrella to conserve other sagebrush (Artemisia spp.)-obligate wildlife, including songbirds. Sagebrush-obligate songbirds and sage-grouse have undergone population declines throughout the western United States attributed to similar habitat issues. We compared trends of sagebrush-obligate songbirds from the Breeding Bird Survey and sage-grouse lek counts in 2 sage-grouse populations in Wyoming (Powder River Basin and Wyoming Basins), USA from 1996–2013. Our evaluation was focused on similarities among population performance of the umbrella species and the species under that umbrella. Sagebrush-obligate songbird and both sage-grouse populations occupied habitat within and outside of protected core areas. Trends of sagebrush-obligate songbirds were not parallel or consistently similar in trajectory to sage-grouse in either core or non-core areas. Our results indicated core areas were successful at maintaining higher sage-grouse trends compared to areas not protected under the core area policy. However, sagebrush-obligate songbird trends did not follow the same pattern. This suggests that protection of only the best sage-grouse habitat may not be a sufficient conservation strategy for other sagebrush-obligate birds

    Rancière and the poetics of the social sciences

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    This article reviews the significance of Jacques Rancière’s work for methodological debates in the social sciences, and education specifically. It explores the implications of framing methodology as an aesthetic endeavour, rather than as the applied technique of research. What is at stake in this distinction is the means by which research intervenes in social order and how it assumes political significance, with Rancière arguing against a notion of science as the other of ideology. Rancière’s argument for a democratic research practice organised around a ‘method of equality’ is situated in relation to openly ideological’ feminist ethnography. The implications of Rancière’s work for investigating affect in academic discourse and subjectification in education are reviewed in the conclusion

    Robust Stochastic Design of Linear Controlled Systems for Performance Optimization

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    This study discusses a robust controller synthesis methodology for linear, time invariant systems, under probabilistic parameter uncertainty. Optimization of probabilistic performance robustness for [script H]_2 and multi-objective [script H]_2 measures is investigated, as well as for performance measures based on first-passage system reliability. The control optimization approaches proposed here exploit recent advances in stochastic simulation techniques. The approach is illustrated for vibration response suppression of a civil structure. The results illustrate that, for problems with probabilistic uncertainty, the explicit optimization of probabilistic performance robustness can result in markedly different optimal feedback laws, as well as enhanced performance robustness, when compared to traditional “worst-case” notions of robust optimal control

    Framing Contemporary U.S. Wild Horse and Burro Management Processes in a Dynamic Ecological, Sociological, and Political Environment

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    The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all “unbranded or unclaimed” equids on U.S. public lands as “living symbols of the historic and pioneer spirit of the West.” Today, \u3e72,000 feral horses (Equus ferus caballus) and burros (E . asinus ; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management’s maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007–2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat and livestock grazing. Thus, public land management agencies must manage WHB under the multiple-use context. This becomes more problematic when WHB populations go largely unmanaged and excessive equid grazing negatively impacts rangeland vegetation, native wildlife, and livestock forage. In addition, approximately 46,000 WHBs exist in off -range holding facilities, further straining federal budgets. Contemporary management actions are being constrained by: (1) litigation that has stymied federal government WFRHBA enforcement eff orts, (2) public emotional concerns that lack reconciliation with the current situation, and (3) increasing complexity in the laws and subsequent amendments shaping WHB management policy. Collectively, these factors impede the implementation of concrete solutions to restore AML. Consequently, stakeholders are increasing polarized over how WHBs are or should be managed. While the ecological and animal health and welfare implications of unmanaged WHB populations are somewhat understood, publicly acceptable strategies to maintain healthy populations, healthy and functioning rangelands, and multiple uses that sustain wildlife and local communities remain unresolved

    Spatial Ecology Observations From Feral Horses Equipped With Global Positioning System Transmitters

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    Our understanding of the spatial ecology of feral horses (Equus ferus caballus ) and burros (E . asinus ) in the United States is limited. Robust location data are needed to better understand the permeability of Bureau of Land Management Herd Management Area boundaries, relative to feral horse movement patterns and home ranges. To increase our understanding of feral horse movement, in February to March 2017, we deployed global positioning system (GPS) collars on 14 females ≥5 years old that were captured in the Adobe Town Herd Management Area (ATHMA) of southcentral Wyoming, USA. Herein, we report initial results from movement data collected during summer (May 15 to September 15) 2017 for 9 horses. We limited our focus to these 9 horses because we received at least 2 months of continuous GPS location data from them during summer 2017. Feral horse daily movement distances averaged 9.0 km (SE = 0.3), and mean summer total home range size was 40.4 km2 (SE = 6.7). Of GPS location fixes obtained, 44.9% were outside ATHMA and 10.8% were on private land. Our results highlight the types of data that GPS collars can provide and illustrate the difficulties of managing free-roaming species such as horses and burros on landscapes with heterogeneous sociopolitical patterns. Expanded use of such technology on feral horses and burros in the United States will yield greater insight on spatial complexities constraining management

    U.S. Public Opinion of Reproductive Control Options for Free-roaming Horses on Western Public Lands

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    Free-roaming horses (Equus ferus caballus; horses) inhabit public rangelands located primarily in 10 western U.S. states. Recent horse population increases are impacting rangeland ecosystems, native wildlife species and their habitats, and exacerbating conflicts with domestic livestock grazing. While contraceptives and physical sterilization are promising options to manage horse herd levels, public opinion concerning the use of fertility control is not well understood. To better inform policymakers, we completed a rigorous study of a random sample of public land stakeholders across the United States (n = 3,500) in 2020 using a Likert scale online survey to assess their level of agreement with the general use of reproductive controls and their preferences regarding 4 available reproductive control options. We used chi-square likelihood ratio tests to determine the associations between the knowledge of horse origins in North America and horse management in the United States, and public support of contraception and sterilization methods to control horse populations. We also assessed the associations between survey responses and respondent demographics. Most respondents either “somewhat agreed” or “strongly agreed” with the use of contraceptives to control horse birth rates (36.6% and 26.9%, respectively) when no specific type of contraceptive was described. Respondents who believed horses were native to North America “strongly agreed” with the statement regarding the use of contraceptives less often (22.2%) than respondents who recognized that European explorers introduced horses (36.6%) or believed horses arrived by crossing a land bridge (35.8%); however, this association exhibited very low power to predict the response (λ \u3c 0.1). Similarly, while there were some associations indicated by chi-square analyses between demographic variables and support for contraceptives, these associations exhibited very low power to explain the responses. When asked to rank 4 generalized population control options, more respondents ranked physical sterilization as their preferred option (37.1%). There was an association between age and ranking order of sterilization. For ages 18–53, the range was 40.6–45.3%, significantly more than older ages, 54 to ≥73, where the range was 31.1–33.8%. Knowledge did not influence the preference for control options. Our results suggest that our respondents were more supportive of the use of contraceptives or sterilization, when described in generalities, to control the birth rates in free-roaming horses. Our research provides policymakers with objective, novel insights into public knowledge and perceptions concerning the population control of free-roaming horses on designated western rangelands. We encourage the federal, state, and tribal agencies charged with the management of free-roaming horses to develop and deliver outreach programs to better educate public land stakeholders about the ecological and economic impacts of free-roaming horses on western landscapes and efficacy of available population management options to mitigate impact and sustain herds

    Potential and Pitfalls of Prescribed Burning Big Sagebrush Habitat to Enhance Nesting and Early Brood-Rearing Habitats for Greater Sage-Grouse

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    We describe short-term (≤10 yrs) and long-term (\u3e10 yrs) responses of prescribed burning to enhance nesting and early brood-rearing habitat for greater sage-grouse (Centrocercus urophasianus). Our primary objective was to provide a literature synthesis to identify short- and long-term responses of prescribed burning to important components of sage-grouse nesting and early brood-rearing habitats in mountain (Artemisia tridentata vaseyana) and Wyoming (A. t. wyomingensis) big sagebrush. In our synthesis, we evaluated ecological status (bare ground and litter), food availability (forbs and insects), and vegetation structure (grass and sagebrush cover). We used six criteria to identify n = 12 papers providing meaningful and rigorous results. Of these papers, six reported the effects of burning in mountain big sagebrush; seven in Wyoming big sagebrush; and one provided information for mountain and Wyoming big sagebrush. Our findings point to some potential for short-term enhancement of forbs and grasses in mountain big sagebrush, but no long-term enhancement of herbs in mountain big sagebrush or short- or long-term enhancement of herbs in Wyoming big sagebrush. In particular, prescribed burning leads to a pronounced negative response in sagebrush cover that lasts for at least a few decades. Based on our findings, we cannot recommend burning Wyoming big sagebrush to enhance sage-grouse nesting or early brood-rearing habitat and we suggest prescribed burning has limited short-term value in enhancing forbs and grasses for sage-grouse inhabiting Mountain big sagebrush

    Increased Abundance of the Common Raven Within the Ranges of Greater and Gunnison Sage-grouse: Influence of Anthropogenic Subsidies and Fire

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    The common raven (Corvus corax; raven) is native to North America and has increased in abundance, especially throughout western North America, during the last century. Human subsidies have facilitated raven dispersal into less suitable habitats and enabled these populations to maintain higher annual survival and reproduction. Concomitantly, overabundant raven populations are impacting other native at-risk species such as the greater sage-grouse (Centrocercus urophasianus) and potentially the Gunnison sage-grouse (C. minimus). Using Breeding Bird Survey data from 1995–2014, we evaluated raven count data to quantitatively describe changes in abundance and expansion into sagebrush (Artemisia spp.) ecosystems, specifically sage-grouse habitat. We focused our analyses on the 7 sage-grouse management zones (MZs) delineated across 11 western U.S. states and 2 Canadian provinces. We assessed the effects of land cover and anthropogenic disturbance on instantaneous growth rate (r) or carrying capacity (K) of ravens. Abundance of ravens in western and southeastern MZs was greater than northeastern MZs within the greater sage-grouse range. While raven abundance was lower in MZ I and II (Alberta, Canada; Dakotas, Montana, and northwestern Colorado, USA; Saskatchewan, Canada; and Wyoming, USA), raven expansion and percent increase were equivalent or greater than all other MZs. High abundance in MZ VII indicated Gunnison sage-grouse have been exposed to increased raven populations for several decades. Areas with greater electric power transmission line density had higher r; higher K was positively related to proportion of urban land cover within 25 km and burned area within 3 km and negatively related to greater distance from landfills and proportion of forest land cover within 15 km. Ravens have capitalized on human subsidies to increase abundance and expand into sagebrush ecosystems that did not historically support high raven populations. As such, managers are now faced with a new dilemma of reducing populations of a native species to benefit other native sagebrush obligate species

    Greater Sage-Grouse (Centrocercus Urophasianus) Select Nest Sites and Brood Sites Away From Avian Predators

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    Greater Sage-Grouse (Centrocercus urophasianus) have declined in distribution and abundance in western North America over the past century. Depredation of nests and predation of chicks can be two of the most influential factors limiting their productivity. Prey species utilize antipredation behaviors, such as predator avoidance, to reduce the risk of predation. Birds in general balance the dual necessity of selecting cover to hide from visual and olfactory predators to enhance prospects of survival and reproductive success, which may also be achieved by selecting habitat with relatively fewer predators. We compared avian predator densities at Greater Sage-Grouse nests and brood locations with those at random locations within available sage-grouse habitat in Wyoming. This comparison allowed us to assess the species\u27 ability to avoid avian predators during nesting and early brood rearing. During 2008–2010, we conducted 10-min point-count surveys at 218 nests, 249 brood locations from 83 broods, and 496 random locations. We found that random locations had higher densities of avian predators compared with nest and brood locations. Greater Sage-Grouse nested in areas where there were lower densities of Common Ravens (Corvus corax), Black-billed Magpies (Pica hudsonia), Golden Eagles (Aquila chrysaetos), and hawks (Buteo spp.) compared with random locations. Additionally, they selected brood-rearing locations with lower densities of those same avian predators and of American Kestrels (Falco sparverius), compared with random locations. By selecting nest and brood-rearing locations with lower avian predator densities, Greater Sage-Grouse may reduce the risk of nest depredation and predation on eggs, chicks, and hens
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