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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer

Bergman, Eric James 11 October 2013 (has links)
<p>The management and research of mule deer (<i>Odocoileus hemionus </i>) in Colorado and throughout the Rocky Mountain West is an exciting arena for wildlife professionals as the prevailing view among biologists, managers, researchers, hunters, wildlife viewers and general wildlife enthusiasts is that they would like to see more deer on the landscape. </p><p> In Chapter 1, I used 4 years of data and 8 study units to evaluate the effect of habitat management on the overwinter survival of mule deer fawns. Habitat management consisted of different levels of habitat management efforts: reference study units received no habitat management, traditional habitat treatment units received mechanical disturbance and advanced habitat treatment units were comprised of both mechanical disturbances as well as follow-up chemical control of weeds and reseeding with desirable browse species. Mule deer fawns that overwintered on areas that received both a traditional treatment as well as follow-up treatments experienced an improvement in survival (<i> &Scirc;</i> = 0.768, SE = 0.085) over deer on winter range without habitat treatments (<i>&Scirc;</i> = 0.675, SE = 0.112). When partitioned into different levels of treatment intensity, mule deer inhabiting winter range that advanced treatments (i.e., both traditional treatments and follow-up treatments) experienced higher survival (<i>&Scirc;</i> = 0.768, SE = 0.0849) than deer on areas that experienced only traditional treatments (<i>&Scirc;</i> = 0.687, SE = 0.108), which in turn experienced higher survival than in areas that had received no treatments (<i>&Scirc; </i> = 0.669, SE = 0.113). </p><p> In my second chapter, I relied on recent advancements in abundance estimation methodologies to determine if habitat management strategies increased mule deer density. In order to estimate mule deer density, I conducted annual helicopter mark-resight surveys across the 8 study units that were utilized in chapter 1. Resighting probabilities (range 0.070&ndash;0.567) were best modeled as an interactive function of study unit and year, although sampling method was also important. A consistent pattern of higher deer density on advanced treatment study units was not observed despite its being the primary hypothesis of the study. Total deer densities did vary by latitude with 20&ndash;84 deer/km&sup2; in southern study units and 4&ndash;12 deer/km&sup2; in northern study units. I conclude that if population density is to be used as a population response variable, it only be used in tandem with other, possibly more sensitive parameters, such as overwinter survival of mule deer fawns. </p><p> In my third chapter, I investigate the relationships between habitat, body condition, and life history characteristics. With the increased availability of portable ultrasound machines and the refinement of hormonal assays, assessment of ungulate body condition has become a more accessible monitoring strategy. I employed body condition scoring, estimation of % ingesta-free body fat (%IFBF) and assessment of thyroid hormones (FT4 and FT3) as metrics to determine if landscape-level habitat manipulation affected body condition of adult (&ge;1.5 years old) female mule deer. </p><p> For my final chapter, I assimilate the knowledge and information gained from my first 3 chapters with the existing knowledge base surrounding mule deer population dynamics and population limitation within Colorado. Such reviews have been conducted periodically (e.g., 1960s and late 1990s) and have been precipitated by mule deer population declines. A dramatic decline in mule deer populations was detected during the final years of my field research but the underlying cause of this decline is yet to be determined. (Abstract shortened by UMI.)</p>
2

Genetic determination of phragmites and small mammals use of remnant patches along the Central Platte River, Nebraska

Frisch, Jennifer Dawn 11 June 2015 (has links)
<p> Invasive phragmites (<i>Phragmites australis</i>) has encroached on the central Platte River in recent years potentially out-competing native stands of phragmites. Invasive stands are thought to have an overall negative impact on ecosystems, but do provide ecological benefits to some species as food or shelter. Little research has been conducted on its impacts on small mammals. The goals of this project were to identify potential native and invasive stands along the central Platte River and determine small mammals use of invasive phragmites. I examined 35 phragmites samples along the central Platte River using restriction fragment length polymorphism. I used molecular sequencing and morphological features to identify stands. All samples were determined to be invasive. Four study sites along the Platte River were selected to evaluate phragmites use and potential impacts on small mammals. Each study site was in a wooded grassland area and consisted of three patches of invasive phragmites and three patches of wooded grassland vegetation. Study sites were sampled using Sherman live traps from April to October 2014. I found no significant difference in overall small mammal use between vegetation types and no seasonal difference between use of phragmites and wooded grassland stands. I did, however, catch fewer individuals in both habitat types during August. Deer mice (<i> Peromyscus maniculatus</i>) selected native vegetation whereas the white-footed mouse (<i>Peromyscus leucopus</i>), meadow vole (<i>Microtus pennsylvanicus</i>) hispid cotton rat (<i>Sigmodon hispidus</i>) and meadow jumping mouse (<i>Zapus hudsonius</i>) selected phragmites. Capture of hispid cotton rat was the first documentation of this species in Dawson County, Nebraska. Differences in selection by these species could be attributed to their different life histories or habitat preferences. The focus of management for invasive phragmites may not need to focus on total eradication. Additional sampling would be required to document the spatial extent of native phragmites stands along the central Platte River.</p>
3

Social and Scientific Factors Impacting Mule Deer Habitat Conservation in the Intermountain West

Trulove, Nicholas F. 31 July 2013 (has links)
<p> For mule deer (<i>Odocoileus hemionus</i>) in the Intermountain West, alterations to habitat are outpacing strategies to mitigate human disturbance on critical seasonal ranges and migration routes. </p><p> Conserving mule deer habitat requires cooperation between a diverse group of stakeholders, state wildlife agencies, and federal land management agencies. The first chapter of this thesis explores the current and historical relationship between state wildlife agencies, citizen stakeholders, and federal agencies in order to highlight opportunities to improve cooperative habitat conservation in the United States. Conservation is a result of social, political, and economic action, but relies upon science to inform policy. The second chapter explores the seasonal habitat use of mule deer in southwestern Wyoming. In response to low fawn recruitment, the Wyoming Game and Fish Department deployed 15 GPS collars on adult female mule deer in an effort to enhance knowledge of mule deer population dynamics, migrations, and habitat use. The study captured two winter climate regimes, with greater winter severity during the 2010-11 winter compared to the winter of 2011-12. Deer migrated an average of 23.9 km (SE = 2.2) between seasonal ranges, and completed spring migrations nearly one month earlier following the milder winter of 2011-12 (<i>t</i>19 = 5.53, df = 19, <i>P</i> &le; 0.001). Pooled, the average area of winter ranges (1057 ha, SE = 103, <i>n</i> = 26) was larger than summer ranges (423 ha, SE = 51 ha, <i>n</i> = 25) (<i>t</i> = &minus;5.44, df = 49, <i>P</i> &amp;le; 0.001), with no increase or decrease in size of seasonal ranges detected between years (<i>P</i> = 0.243) according to a post-hoc Tukey HSD test. Between years, deer were observed to shift the geographic center of winter ranges (2.9 km, SE = 1.1, <i> n</i> = 12) to a larger degree than summer ranges (0.4 km, SE = 0.1, <i> n</i> = 12) (<i>t</i> = &minus;2.20, df = 22, <i>P</i> = 0.040). Survival and pregnancy rates (86% and 96%, respectively) correlated closely with other mule deer studies, and neither factor appears to negatively impact population growth. </p><p> Identifying seasonal ranges and migration routes, and quantifying seasonal habitat use, will assist Wyoming Game and Fish Department efforts to protect mule deer seasonal habitats and migration routes, and direct vegetation manipulations intended to improve the nutritional quality of habitats. On average, winter ranges included a later percentage of shrub-dominated habitat (83.8%, SE = 0.3, <i>n</i> = 26) than summer ranges (57.5%, SE = 2.0, <i> n</i> = 25) (<i>t</i> = &minus;4.42, df = 49, <i>P</i> &le; 0.001). Summer ranges averaged a greater proportion of agricultural lands (2.8%, SE = 1.1, <i>n</i> = 25) and aspen (<i>Populus tremuloides </i>) habitats (9.0%, SE = 2.2, <i>n</i> = 25) than winter ranges (0.1%, SE = 0.1, <i>n</i> = 26 and 0.2%, SE = 0.0, <i> n</i> = 26, respectively) (<i>t</i> = 3.03, df = 49, <i>P</i> = 0.004 and <i>t</i>= 3.86, df = 49, <i> P</i> &le; 0.001, respectively). Mule deer ranges are primarily located on Bureau of Land Management (73%, SE = 2.8, <i>n</i> = 51) and privately owned (17.3%, SE = 2.9, <i>n</i> = 51) lands, highlighting opportunities for cooperative partnerships for mule deer habitat conservation. </p>
4

Survival, habitat use, and spatiotemporal use of wildlife management areas by female mallards in Mississippi's Alluvial Valley

Lancaster, Joseph David 17 January 2014 (has links)
<p>The Mississippi Alluvial Valley (MAV) is an important region for wintering mallards (Anas platyrhynchos) in North America, yet little is known about their spatiotemporal habitat use and related survival in Mississippi. I tracked 126 radio-marked female mallards to quantify survival, habitat use, and use of wildlife management areas (WMAs) with experimental hunt regimes in the south MAV of Mississippi during winters 2010-2012. Daily survival was greatest in agricultural (0.997) and moist-soil (0.999) habitats in winters 2010-2011 and 2011-2012, respectively. Overall interval survival across both winters was 0.60 (SE = 0.02). Forested (40-54%) and moist-soil wetlands (41-59%) received greatest use diurnally and nocturnally, respectively. Mallards used WMAs similarly (P > 0.22) whether they were hunted 2- or 4-days/week. My data suggest that complexes of flooded cropland, forest, and moist-soil habitats are suitable habitats for mallards in the MAV, WMAs can be hunted 4-days/week, and sanctuaries should be revised at two WMAs.
5

Essays on regulation policy, wildlife quality, and excess demand

Olanie, Aaron Z. 28 November 2013 (has links)
<p> The second chapter examines how both domestic and foreign tobacco regulations affect the flow of tobacco trade. I develop a gravity equation incorporating a comprehensive set of domestic and foreign tobacco regulations into a country's tobacco import demand and estimate their bilateral effects. The results suggest a country's tobacco imports are significantly affected by their trading partner's tobacco regulations. There are two important results: spatial regulations reduce tobacco trade regardless of trade direction and marketing regulations in importing countries may actually increase tobacco imports. These results highlight the importance of understand regulations in an increasingly multilateral economy. </p><p> The third chapter investigates the effects of varying levels of access and excludability on a common pool resource with intrinsic quality characteristics. I analyze the case of deer hunting on leased properties by hunting clubs and estimate the lease size elasticity of both harvest and antler quality. The results suggest lease size has a small but significant effect. For all clubs with smaller than average hunting leases, a simulated increase to the average size results in approximately a 4.5 percent increase in the average antler quality of deer harvested. Although I analyze properties leased by hunting clubs, the results are applicable to various other management scenarios. </p><p> The fourth chapter develops the relationship between excess demand and purchase options. I illustrate a mechanism allowing firms to smooth sales across periods with uncertain quality and increase expected profit over the market clearing strategy. By "underpricing" high quality goods and offering a purchase option guaranteeing a single price regardless of quality, firms create excess demand and increase consumer willingness to pay for their purchase option. The firm maximizes profit by choosing a guaranteed price low enough to create sufficient excess demand and consumer willingness to pay for the purchase option that markets clear when quality is low. Using a numeric example, I demonstrate a case where this behavior increases profit over the market clearing strategy.</p>
6

Applying a social-ecological systems approach to human-bear encounters across the Pacific Rim| Advancing resilient human-wildlife management strategies

Jochum, Kim A. 22 November 2014 (has links)
<p> Wildlife management is challenged with addressing human resource needs while simultaneously conserving wildlife populations. Conflicts between humans and wildlife have increased across Northern countries with the expansion of human communities and environmental changes. Lack of information exists about reasons for such occurrences. This study explores adaptive capacity and resilience in coupled human-wildlife systems through the analysis of social and ecological factors contributing to perceptions of negative and positive human-bear (<i> Ursus</i> spp.) encounters. I first developed a theory to evaluate human perceptions and behaviors during human-wildlife encounters. Secondly I adopted an interdisciplinary framework to analyze human-bear encounters in urbanizing regions of south Sakhalin Island, Russian Far-East, and southcentral Alaska, USA. These case studies facilitate an analysis of perception development across spatial and social scales while incorporating approaches of both social and ecological sciences. Hunting, tourism and overall anthropogenic impacts are central to bear management, whereas cultural and social interests are perceived to not be considered in bear management decision-making across study regions. In Alaska, political interests are prevalent in bear management, whereas on Sakhalin, economic interests, including illegal animal trade and poaching prevail. Across study regions the perception of an encounter with a bear was dependent on the socio-economic situation of the individual having the encounter. The higher a person's socio-economic status was, the higher was their probability to perceive bear encounters as positive. Further, spatial and social scales across which perceptions vary are identified. Scales include urban-non-urban areas, wildland-urban interfaces, and a recreation-subsistence interest divide. Outside of urban areas, people's interests in recreation versus subsistence affect their perceptions toward bear encounters. Subsistence collectors of fish, game or plants are more likely to have negative encounters. Within urban areas, increased experience with encountering bears and length of residency are associated with positive encounters, whereas closeness to residences while not in sheltered environments increases negative encounters. These findings constitute spatial and social barriers and benefits to individualistic perception formation during human-bear encounters. Their identification advances resilience in researched human-wildlife systems and helps us to understand the adaptive capacities within these communities. The successful spatially-explicit integration of social and ecological variables promotes the opportunities for integrating human dimensions in wildlife management.</p>
7

Tidally-induced limits to California clapper rail ecology in San Francisco bay salt marshes

Overton, Cory Tyler 03 May 2014 (has links)
<p> The state and federally endangered California clapper rail (<i> Rallus longirostris obsoletus</i>) has declined in abundance and been reduced in range and now occupies fragmented intertidal saltmarsh only within San Francisco Bay. Historically extensive salt marsh habitats existed in San Francisco Bay and today, remnants are largely restricted to the water's edge with dikes and levees separating marshland from modified habitats unsuitable for clapper rails. Clapper rail population abundance has roughly tracked a series of positive and negative impacts including market hunting at the turn of the 20th century, widespread habitat reduction and fragmentation, and invasive species introduction and eradication programs. Despite these changes, rail populations have been subject to the ebb and flow of the tides, which regularly inundate salt marsh habitats. The influence that tides have on vertebrate species living in intertidal saltmarsh should be substantial, but the relationship between tide and California clapper rails is poorly understood. This research identified important ways in which tides influenced demographic processes, space use, and resource selection in California clapper rails. Tidal inundation in San Francisco Bay saltmarshes creates zonation in plant communities, typically with tall monocots in the low marsh (<i>Spartina </i> sp.), short pickleweed (<i>Sarcocornia pacifica</i>) in mid-elevation ranges, and gumplant (<i>Grindela humilis</i>) in the high marsh. Invasive Spartina (<i>Spartina foliosa x alterniflora </i>) grows taller and thicker than native Pacific cordgrass (<i> Spartina foliosa</i>). Invasive Spartina also grows lower onto mudflats, further up into pickleweed areas, and provided both nesting habitat and tidal refuge for clapper rails. In Chapter 1, I examined survival rates of California clapper rails. Specifically, I investigated whether seasonal patterns observed in the early 1990s were still evident and assessed the influence that Invasive Spartina and the degree of tidal inundation on weekly survival rates in four South San Francisco Bay salt marshes. Between January 2007 and March 2010, California clapper rail annual survival was 73% greater in Spartina-dominated marshes (&Scirc; = 0.482) than in a control marsh dominated by native vegetation (&Scirc; = 0.278). Lower survival also occurred during periods when tide height was greatest and during the winter. Survival patterns were consistent with Invasive Spartina providing increased refuge cover from predators during tidal extremes which flood native vegetation, particularly during the winter when the vegetation senesces. Tide heights also strongly influenced selection for artificial habitats provided adjacent to one marsh during the winters of 2010-2011 and 2011-2012. Ten floating islands equipped with canopies providing cover were monitored using time-lapse cameras for evidence of clapper rail use. Clapper rails regularly used artificial islands once tides reached heights equal to the average surface elevation of the marsh. When tides had inundated the marsh plan, observed use of the artificial islands was more than 300 times expected use based on the surface area provided. Probability of use varied among the islands and low levels of use were observed at night. Endemic saltmarsh species are increasingly at risk from habitat change resulting from sea-level rise and development of adjacent uplands. Escape cover during tidal inundation may therefore need to be supplemented if species are to survive. I developed a new method to estimate space use accounting for individual movement phases within non-stationary relocation datasets using simulated radio-telemetry data. To define movement phases I used a nonparametric, multivariate test to detect change points in the mean or variance of a sequence of x,y coordinates. Once all phases (change points) were identified, Gaussian kernel density analysis was used to estimate space use during each phase, which I termed change-point utilization distributions (CPUDs). One advantage of this technique is that the location of change points can subsequently be tested for relationships with conditions that might trigger a change in how individuals use space. Change points in clapper rail movement were associated with a variety of environmental and biotic variables including high tides, nesting activity, intrusion by neighboring clapper rails, and transient movements outside the home range. Change points occurred more than twice as frequently during the highest observed tides relative to all other tide heights. Another use of CPUDs is that space use patterns of adjacent individuals can be evaluated for joint overlap only during specific time periods when overlap occurs. I used CPUDs developed for California clapper rails and identified the point within overlapping space-use estimates where each individual had priority access to the resources within its utilization distribution (i.e. the lowest kernel density isopleth that was common to two overlapping individuals). This provided an estimate of the spatial region at which individuals exhibited territoriality. During the breeding season, space use distributions overlapped less and average territory size increased relative to the non-breeding seasons. Population density implied by these territory sizes (1.38 birds/ha) is comparable to density estimates during the 1970s and 1980s. Together these findings show the great degree to which clapper rail behavior and demography can be influenced by the tides that populations experience. It is my hope that conservation efforts for this species, particularly in the arena of habitat restoration may benefit from this research.</p>
8

DNA-based Population Estimation, Harvest Vulnerability, and Home Range Dynamics of Black Bears in Western Maryland

Jones, Michael D. 02 May 2013 (has links)
<p> After nearly being extirpated from the state, black bears in Maryland have rebounded to a point where recreational harvest has now become an important management tool. Having a better understanding of bear population parameters, movements, and harvest vulnerability allows managers to implement hunting more effectively and responsibly. To estimate demographics of the Maryland bear population, we implemented noninvasive genetic sampling of bear hair during summer 2011. We used a model-based sampling design that allowed us to collect samples more efficiently. We used presence-only maximum entropy (Maxent) modeling to classify the study area based on predicted probability of bear occurrence, and allocated the majority of our hair snares to areas with high or medium probabilities. Using microsatellite analysis and mark-recapture methods, we estimated the bear population at 701 individuals. This represents a nearly doubling of the population since the previous estimate in 2005. Our density estimate (0.25 bears/km<sup>2</sup>) is comparable to other estimates from southeastern and mid-Atlantic states. Our sampling approach did lead to more efficient sample collection, with more hair samples collected at snares located in areas with predicted high or medium probability of bear occurrence than those in low probability areas. However, in the eastern portion of our study area, where bear occurrence is presumed to be much lower, our sampling effort seemed insufficient to collect enough samples for reliable abundance estimation. As a first step toward quantifying harvest vulnerability, we used Global Positioning System (GPS) units to record movements and spatial behaviors of 108 bear hunters during the 2005&ndash;2007 Maryland bear hunting seasons. Median values showed that hunters traveled 2.9 km per hunting event, but only 0.6 km from their starting point. Hunters did not seem to show any preferential use of areas based on the landscape metrics we examined (e.g., elevation, distance from nearest road) except cover type, where 81% of locations were in deciduous forests. We found few differences between spatial behaviors of groups of hunters based on harvest success, residency, and previous bear hunting experience, as classified using post-hunt mail surveys. One notable difference is that successful hunters used steeper slopes than unsuccessful hunters. We also found that hunter perceptions of total distance traveled and distance from nearest roads were often highly inaccurate, showing that hunter surveys are not a useful tool for collecting those data. For Garrett County, Maryland, we used the hunter locations to create a Maxent model of the spatial distribution of harvest pressure. We also created a model using fall telemetry locations of female bears and compared the models to identify areas of high (i.e., high hunter and high bear occurrence) and low (i.e., low hunter and high bear occurrence) harvest vulnerability. Both models showed higher probability of occurrence on public lands. Both high and low vulnerability areas comprised small portions of the county. The low vulnerability areas included 9 larger blocks (>1 km<sup> 2</sup>), which were 2.3 times steeper, 2.0 times farther from roads, and 1.5 times farther from streams than the medians for the study area. Those characteristics may limit hunter access to and use of the areas. Our predicted high vulnerability areas did not correspond to most previous bear harvest locations, indicating that our definition of harvest vulnerability often does not translate to actual harvest. Finally, we used GPS collars to track female bear locations in Garrett County and examine home range dynamics. Fixed kernel estimates for annual, spring, summer, and fall home ranges were 10.40 km<sup> 2</sup>, 8.93 km<sup>2</sup>, 16.08 km<sup>2</sup>, and 19.35 km<sup> 2</sup>, respectively. Fall and summer home ranges were larger than spring home ranges, but summer and fall ranges were similar. Solitary females had mean spring home ranges 6.9 times larger than females with cubs-of-the-year, but ranges did not differ during other seasons. Bears exhibited high levels of home range fidelity, with home range centroids shifting little among seasons or years. Intraspecific overlap of home ranges occurred during all 3 seasons, but was most common in summer. The results of this study provide Maryland bear biologists and managers with essential information about the state&rsquo;s bear population. Home range estimates represent important baseline information to determine appropriate spatial scales of management. The abundance estimates will be used to set proper harvest quotas with the goal of slowing the bear population growth. The hunter movement analysis and harvest vulnerability modeling may be used by managers to adjust harvest regulations to increase the efficacy of the hunting seasons.</p>
9

Is spot mapping missing important aspects of golden-winged warbler (Vermivora chrysoptera) breeding habitat?

Frantz, Mack Wilson 30 May 2013 (has links)
<p> The Golden-winged Warbler (<i>Vermivora chrysoptera</i>) is an imperiled migratory songbird that nests in young forest habitats of eastern North America. As such, this species has recently been the focus of an intensive multi-year, range-wide, breeding ecology study. A major focus of this research involved spot-mapping color banded males to examine relationships between nesting success and territory-scale habitat variables. I compared differences in space and habitat use of individual male Golden-winged Warblers that were monitored using both spot mapping and radio telemetry. An individual's telemetry delineated use area was on average 3.6 times larger than its spot-mapped territory. Almost half (46%) of all telemetry locations were located outside their respective male's spot-mapped territory. Number of saplings was higher in telemetry use areas (22.49 &plusmn; 2.14) than spot-mapped territories (11.80 &plusmn; 1.86). Although the exact motive for extra-territorial movements is unknown, foraging and/or suggestive observations of extra-pair copulation are likely motivating factors. The results of my study suggest Golden-winged Warblers are seeking resources outside their spot-mapped delineated territories. Furthermore, Golden-winged Warblers were found to have more telemetry locations in mature forest than found through spot-mapping. Ultimately, spot mapping alone does not accurately reflect Golden-winged Warbler space use and habitat needs.</p>
10

Common raven density and greater sage-grouse nesting success in southern Wyoming| Potential conservation and management implications

Dinkins, Jonathan B. 05 September 2013 (has links)
<p> My research was focused on greater sage-grouse (<i> Centrocercus urophasianus</i>; hereafter "sage-grouse") nest-site selection, nest success, and hen survival in relation to avian predators. The trade-off between using habitat and avoiding predators is a common decision for prey species including sage-grouse. In Chapter 2, I compared avian predator densities at sage-grouse nest and brood locations to random locations. Sage-grouse were located where densities of small, medium, and large avian predators were 65-68% less than random locations. </p><p> The effects of anthropogenic and landscape features on habitat use of sage-grouse hens have not been evaluated relative to avian predator densities. In Chapter 3, I compared anthropogenic and landscape features and avian predator densities among sage-grouse locations (nest, early-brood, late-brood) and random locations. I found sage-grouse hens chose locations with lower avian predator densities compared to random locations, and selected locations farther away from anthropogenic and landscape features. </p><p> Depredation of sage-grouse nests can be an influential factor limiting their productivity. Predator removal has been simultaneously proposed and criticized as a potential mitigation measure for low reproductive rates of sage-grouse. In Chapter 4, I hypothesized that sage-grouse nest success would be greater in areas where Wildlife Services lowered common raven (<i> Corvus corax</i>: hereafter "raven") density. I found that Wildlife Services decreased raven density by 61% during 2008&ndash;2011 but I did not detect a direct improvement to sage-grouse nest success. However, sage-grouse nest success was 22% when ravens were detected within 550 m of a sage-grouse nest and 41% when no raven was detected within 550 m. In Chapter 5, I assessed interactive effects of corvid densities relative to anthropogenic and landscape features on sage-grouse nest success. I found that sage-grouse nest success was positively correlated with rugged habitat. </p><p> Survival of breeding-age birds is the most important demographic parameter driving sage-grouse abundance. In Chapter 6, I evaluated the effect of raptor densities, proximity to anthropogenic and landscape features, and hen behavior on survival of sage-grouse hens. I found that sage-grouse hen survival was negatively correlated with golden eagle (<i>Aquila chrysaeto</i>s) density, proximity to anthropogenic and landscape features, and hen parental investment (nesting and brood-rearing).</p>

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