• Dissertation Defense
• 07/17/2025

The Pallid Sturgeon (Scaphirhynchus albus), a long-lived, benthic fish that has inhabited the Mississippi–Missouri River system for over 70 million years, plays a vital ecological role. However, extensive habitat degradation and limited natural recruitment have pushed the species to the brink of extinction, prompting large-scale conservation efforts centered on hatchery propagation. Despite these interventions, hatchery-reared Pallid Sturgeon often exhibits reduced post-release survival and frequent disease outbreaks, raising concerns about their long-term viability. These issues have drawn attention to gut microbiome as a key factor in host health, disease resistance, and environmental adaptability.

Using 16S rRNA gene sequencing, I found that hatchery-reared sturgeon harbored substantially lower microbial diversity (147 ASVs across 44 fecal samples) compared to wild counterparts (369 ASVs from 20 individuals), alongside marked shifts in taxonomic structure. Seasonal patterns also emerged as significant drivers of microbial composition, indicating that timing of stocking could be optimized to favor beneficial microbial colonization.

I conducted a six-month probiotic intervention in hatchery fish to address microbiome restoration. Probiotic exposure promoted the enrichment of beneficial taxa such as Cetobacterium, Clostridiaceae, Peptostreptococcaceae, and Lachnospiraceae, which are linked to nutrient metabolism, mucosal integrity, and pathogen resistance. Probiotic-treated fish also demonstrated improved thermal tolerance. A pilot study on Flathead Catfish revealed that microbial shifts could begin within just 30 days of captivity, even in the absence of major changes in diversity or abundance.

Altogether, these findings emphasize the ecological importance of the gut microbiome and support the integration of microbial strategies-such as seasonally informed stocking and probiotic supplementation into conservation aquaculture. Incorporating microbiome science offers a novel and effective tool for improving the health and adaptability of endangered fish in recovery programs.

• Dissertation Defense
• 06/27/2025

Biofuel and bioenergy systems are critical components of most proposed climate stabilization strategies aimed at reducing greenhouse gas (GHG) emissions and limiting global warming. In the United States, corn (Zea mays) is the dominant feedstock for bioenergy production. However, the reliance on large-scale monoculture agriculture has contributed to the degradation of natural resources and the disruption of key ecological processes. One of the most severe consequences of agricultural expansion for bioenergy is the widespread loss of native grassland habitats, a largely unprotected ecosystem, across the Great Plains. This habitat loss has been a major factor in the decline of many grassland bird species, more than any other avian group. To meet renewable fuel targets while also addressing biodiversity loss, particularly among declining grassland bird populations, alternative bioenergy crops must be considered. Switchgrass (Panicum virgatum), a native C4 perennial grass, has emerged as a promising candidate. It offers the dual benefit of producing substantial biomass for bioenergy while supporting biodiversity and enhancing ecological function. Understanding how the integration of bioenergy-dedicated grasslands into agricultural landscapes affects grassland bird communities is essential for informed land management decisions. This study aimed to assess how low-diversity perennial grasslands, similar to grasslands suitable for bioenergy production, influence focal grassland bird species across multiple spatial scales. We employed both innovative technologies, including autonomous acoustic monitoring, and conventional methods such as point count surveys, to gain comprehensive insights into avian responses to bioenergy-driven land-use changes. Along with ecological research, we also employed qualitative interviews with landowners in the region to explore Nebraska landowners' perspectives on land use in the Great Plains. The results of this study enabled a direct comparison of the effects of perennial grassland and cropland habitats on avian populations at multiple scales as well as informed recommendations for the successful integration of switchgrass fields into agricultural landscapes.

• Dissertation Defense
• 06/13/2025

Long ago, in a time forgotten, a wet climate threw the dunes of the Nebraska Sandhills out of balance. Grasslands proliferated, stabilizing dune complexes as upwelling groundwater birthed a horde of shallow lakes. In a land where temperatures can exceed 100 degrees Fahrenheit and plummet well-below freezing, change is afoot. The cold is returning, and in the frozen wastes of the Nebraska Sandhills, ice is amassing across lakes. Yet, summer grassland wildfires abound; initiating novel environmental circumstances for Sandhills lakes. At the center of these events lies climate change, a disturbance as harsh and unyielding as the windswept and sun-bleached Sandhills. Sweeping from a harsh land of cold to a summertime of scorching heat, A Study of Ice and Fire tells a tale of nitrogen, phosphorous and algae, who come together in the unrelenting maelstrom of biogeochemical cycles and environmental change. Here, groundwater inputs and evaporation form complex and nutrient-rich brines; lake color reveals cryptic ecological dynamics; seasonal and interannual variability carries limnologists off into madness; algal biomass proliferates; lake ice cover waxes and wanes in accordance with atmospheric temperatures; dissolved oxygen is consumed entirely under ice cover, ferrying fish beyond the Wall; wildfire ash blunts the advance of light into aquatic environments; and nitrogen-limited lakes remain unspoiled by the hot tongue of fire. Amid sinking watercraft and labyrinths of undocumented R code, treacherous lab and field work, cruel budget cuts and victorious grant applications, high-stakes committee meetings and conspiratorial coffee breaks, allies and crafty PhD advisors, the story of the Sandhills lakes unfolds, as an intrepid limnologists endeavors to survive that deadliest of conflicts: graduate school.

• Thesis Defense
• 04/28/2025

Spatial ecology and predator-prey interactions are central to ecology and conservation. We used GPS telemetry data to evaluate mountain lion ( Puma con color) home range size, predator-prey interactions, and resource selection in California’s San Francisco North Bay, USA. In Chapter 1, we evaluated home range size, prey composition, and black-tailed deer ( Odocoileus hemionus columbianus ) kill rates across an urban-rural gradient to investigate how human disturbance influences these aspects of mountain lion ecology. We found sex-specific differences in home range size as both males and females increased their home range size at low to moderate levels of development but at higher levels, female home ranges stabilized while male home ranges decreased, possibly due to constrained movement. Feeding time, prey composition, and deer kill rates did not vary relative to human infrastructure or natural landscape features relevant to predation (e.g., cover, productivity). However, the rate at which mountain lions killed deer in the North Bay was generally comparable to estimates reported in both natural and disturbed systems. In Chapter 2, we investigated scale-dependent strategies by mountain lions relative to their primary limiting factors along a gradient of human disturbance. Mountain lions appear to adopt flexible, scale-dependent strategies in human- dominated landscapes, allowing them to select home ranges in more developed and natural portions of the urban-wildland interface. Our results also highlight that ecological theories conceptualized in relatively undisturbed landscapes do not necessarily predict large carnivore behavior in landscapes heavily modified by humans. In Chapter 3, we evaluated resource selection by mountain lions at locations where they consumed black-tailed deer. Mountain lions selected vegetative cover more strongly than productivity, suggesting they prioritize structural habitat features that promote successfully killing prey, rather than productive areas that maximize encounters with prey. However, selection of productivity increased as a function of cover, indicating that mountain lions exhibited the strongest selection of areas with vegetative features in which prey were likely both abundant and vulnerable. Collectively, our results offer valuable insight into predator-prey interactions in human-dominated landscapes, a key knowledge gap in ecology and conservation, by quantifying these interactions, evaluating multi-scale responses to prey availability and human disturbance, and identifying features that mountain lions selected and avoided when feeding on their primary prey, black-tailed deer.

• Dissertation Defense
• 04/21/2025

Urban forests are valued as green infrastructure for the variety of benefits they provide across ecological, social, public health, and economic domains. To understand the distribution of trees, maps are required. Many methods of mapping tree cover use expensive and data-intensive datasets such as hyperspectral and LiDAR imagery, making these methods inaccessible to municipal forest managers. Variations in the modelling approaches of existing, freely available methods are not addressed in sufficient enough detail to understand the trade-offs implicit in these variations. Further, characteristics of urban tree canopy mapping (high spatial resolution imagery, heterogeneous urban environments, the importance of the tree class) make it unclear to what extent results derived from other contexts apply. This dissertation addresses uncertainties related to feature selection methods, spatial variability of accuracy assessments, trade-offs involved in the use of different training sampling schemes and sample sizes, sources of classification error, and error in the reference map. Further, this dissertation proposes an optical method for change detection in urban tree canopy maps and compares estimates of tree cover derived from simple image differencing, a correspondence change detection method, and change detection performed with a reference method that incorporates LiDAR data. Random forest-based feature importance was found to be a more effective feature selection method than Kruskal-Wallis test of independence and correlation-based feature selection. The accuracy assessment varies spatially due to low inter-class variability, which can be characterized by unsupervised clustering. Sampling schemes should be determined considering the relative cost of error. Simple random sampling minimized commission error, stratified even sampling minimized omission error, and disproportionate stratified random sampling balanced commission and omission errors. Stratified even sampling was able to produce accurate maps with fewer samples. Maps produced with optical methods had overall agreement between 84.0-87.4% with optical + LiDAR maps when reference errors were corrected. Simple image differencing produced similar estimates of stable tree cover and tree canopy gain, but not tree canopy loss. The correspondence method visually improved parallax-induced errors and yielded high user’s accuracy for the stable tree class at the cost of greater omission error.

• Thesis Defense
• 04/16/2025

Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively bigheaded carp) have invaded tributaries to the Missouri River and Platte River in Nebraska, USA. Information pertaining to efficient sampling protocols for assessing bigheaded carp populations as well as benefiting removal efforts is needed. Herding is a method used to increase the capture efficiency and detection probability of adult bigheaded carp by simultaneously using active and passive sampling gears. During June-July 2023, four herding techniques were assessed regarding their ability to elicit directional movement past an enclosure gate. The combination of sound and electrofishing resulted in the highest mean number of bigheaded carp successfully herded, followed by electrofishing, sound, boat and motor only, and the control. Mean depth was shown to influence herding effectiveness and exhibited a positive relationship. During the summer of 2024, boat electrofishing and herding with gill nets were conducted on three tributaries of the Missouri River and one tributary of the Platte River and compared based on capture efficiency and cost-effectiveness. A total of 6,205 bigheaded carp were collected, with herding resulting in the capture of 2.8 times more bigheaded carp than electrofishing. Herding (437.3 fish/hr) had a higher mean catch-per-unit-effort (CPUE) than electrofishing (155.0 fish/hr) when accounting for gear effort (i.e., run time). However, electrofishing (39.0 fish/person-hr) had a greater CPUE than herding (20.1 fish/person-hr) with the inclusion of overall effort (i.e., labor hours and crew size). In achieving an equivalent weekly catch, electrofishing was more cost effective than herding. The results of this study will provide managers, researchers, and stakeholders knowledge regarding efficient and cost-effective sampling strategies for invasive bigheaded carp that enable assessments of presence and population status as well as provide control options for population reduction and potential removal.

• Dissertation Defense
• 01/06/2025

Walleye Sander vitreus and Sauger Sander canadensis are both socioeconomically important sportfish species in Lewis and Clark Lake, an interjurisdictionally-managed mainstem Missouri River reservoir fishery. Since 2011, adult catch per unit effort (CPUE) of both Walleye and Sauger has remained at approximately 50% of pre-2011 levels. A presumed reason for the suppressed CPUE of adult Walleye and Sauger is substantial entrainment of larval and adult fish resulting from the reservoir’s high turnover rate (7.2 d). Acoustic telemetry was used to quantify adult movement and entrainment and ichthyoplankton trawls were used to assess larval entrainment. Relative importance of factors driving larval entrainment through Gavins Point Dam (GPD), abundance of age-0 fish in the reservoir, and adult movement patterns were assessed using an information theoretic approach. The models with the most support for explaining variation in larval entrainment were week of year and air temperature for Fort Randall Dam (FRD) and water temperature, day of year, and cumulative days of sustained high discharge for GPD. Age-0 Walleye abundance was most supported by mean outflow through GPD, mean annual precipitation, and delta April gage height. Age-0 Sauger abundance was most supported by adult conspecific abundance, April heating degree days, and annual precipitation. Mean weekly adult Walleye movement was most supported by reservoir elevation, season, and mean weekly air temperature. Mean weekly adult Sauger movement was most supported by discharge through FRD and season. We observed that annual larval entrainment (both total including all species and Walleye and Sauger entrainment) through GPD is greater than larval entrainment through FRD during 2021-2024. Further, entrainment and exploitation are considerable sources of loss for adult Walleye and Sauger. Our findings suggest flow is a driving factor affecting abundances of larval Walleye and Sauger and flow is affecting abundances and movement patterns of adult Walleye and Sauger in the reservoir.      

• Thesis Defense
• 12/03/2024

American bison (Bison bison) are a keystone species that impact grassland productivity, plant diversity, and landscape heterogeneity. We used GPS telemetry and a replicate herbivore grazing experiment on Vermejo Park Ranch in northeastern New Mexico to advance understanding of bison spatial ecology and grazing dynamics. First, we evaluated the potentially disparate influences of forage productivity and site fidelity on the size and selection of home ranges of bison. Home range size was strongly negatively influenced by forage productivity. However, home range selection was influenced more strongly by site fidelity than spatial variation in forage, as bison selected home ranges with lower forage productivity relative to what was available across Vermejo. Second, we investigated whether collective grazing by bison in lower elevations modified plant growth to produce high-quality forage that released them from the need to migrate to higher elevations. Although forage productivity and graminoid quality were greater in higher elevations, bison in lower elevations maintained a diet of similar quality to bison translocated to higher elevations. Vegetation responded to ungulate grazing (mainly bison and elk) with equal or enhanced productivity in both years of our study, indicating that grazing levels likely improved (rather than degraded) ecosystem productivity. Third, we evaluated movement-based resource selection by bison during migratory-like travel. During these long-distance movements (mean = 19.0 km, range = 11.0 – 23.3 km), bison alternated between stationary, meandering, and directed movement states. Bison selected higher forage productivity in stationary and meandering states, whereas they avoided higher elevations and steeper slopes during directed movement. These results suggest an expanded perspective of stopover ecology that includes short-term shifts between directed travel and periods of foraging and rest whereby animals can alternatively prioritize optimal foraging and efficient travel during migration. Our work advances understanding of energetic tradeoffs between site fidelity and migration, the influence of grazing by large ungulates on ecosystem productivity, and behavioral strategies used by animals to fuel migration.

• Thesis Defense
• 11/22/2024

Consideration of spatial patterns and processes is fundamental to developing research studies, implementing management actions, and planning restoration efforts. The Red River of the North basin spans a broad geographic area, where jurisdictional oversight is divided among several entities (Manitoba, CAN; North Dakota, USA; Minnesota, USA; South Dakota, USA), creating a mosaic of regulatory and functional process zones. In this disjointed landscape, understanding the spatial ecology of freshwater fish is essential to address diverse life history requirements and the movement constraints imposed by anthropogenic structures. Long-term acoustic telemetry revealed that large bodied ichthyofauna employ a diverse range of movement strategies throughout the basin. Lake Whitefish showed the highest likelihood of migratory behavior, averaging the longest linear distance between migratory ranges (196.5 km, SD = 23.9), and a strong fidelity to spawning and overwinter locations. Lake Sturgeon, Bigmouth Buffalo, Freshwater Drum, and Walleye displayed the capacity to make annual displacements exceeding 350 km. Lake Sturgeon were the most rigid in their annual movement strategy, forming distinct groups with consistent movement patterns. Bigmouth Buffalo crossed over anthropogenic structures and across the international border more frequently than all species. Burbot and Channel Catfish movements were more restricted, typically remaining in the region in which they were tagged. Examination of demographic rates of Freshwater Drum found no differences in mortality, growth coefficient, or asymptotic length among sampling reaches in the United States, potentially owing to this species’ capacity for broad-scale movement. Our growth estimates (K, Brody growth coefficient) align with studies conducted as far south as Alabama, while mortality rates (4–10%) and longevity (up to 62 years) reflect established latitudinal trends. Recruitment variability (recruitment variability index = 0.53) was associated with thermal and hydrologic factors, including a positive relationship with growing season degree days and negative associations with cold-season discharge and rise rate. These insights into both movement and population dynamics provide further understanding of species ecology, which can be used to improve management practices and direct future conservation actions.    

• Thesis Defense
• 11/21/2024

Pallid Sturgeon (Scaphirhynchus albus) are centenarian, potamodromous, rheophiles that historically occupied the Missouri River and Mississippi River basins. Listed on the U.S. Endangered Species Act in 1990, population declines are attributed to habitat fragmentation and degradation, as well as overharvest, and hybridization. A knowledge gap exists regarding the extent to which tributaries facilitate key life stages for Pallid Sturgeon. This study evaluated the capacity of acoustic telemetry to monitor the movements of Pallid Sturgeon in a shallow, braided tributary to the Missouri River. The specific objectives were to (1) evaluate the environmental variables influencing the performance of acoustic telemetry, and to (2) quantify movement, residency, and seasonal space use of adult and sub-adult Pallid Sturgeon in the lower Platte River, Nebraska. Rigorous range testing protocols were employed, revealing relatively low detection ranges (<200 m) compared to other rivers throughout the region. Long-term reference tags revealed high variability in detection range, influenced primarily by line-of-sight, discharge, and water depth. Viewshed analyses were also employed to quantify detection range and may be a cost-effective alternative to formal range testing in systems where line-of-sight limits detection. A total of 80 Pallid Sturgeon were detected through active and passive telemetry, including sub-adults, reproductive adults, and non-reproductive adults. Space use models were created for 72 adults and 6 sub-adults. Pallid Sturgeon movements predominantly occurred at night, with a higher degree of residency in the Platte River compared to the Missouri River. Further, adult Pallid Sturgeon exhibited greater space use areas compared to subadults. Distinct migration strategies were documented, including one-step and two-step migrations, with overwintering occurring throughout the lower Platte River basin. Results confirmed that, despite low performance of acoustic telemetry in shallow, sand-braided rivers, species-specific designs can yield valuable movement information. The study emphasized that the lower Platte River basin provides important resources for the survival and persistence of multiple life-stages of Pallid Sturgeon.

• Thesis Defense
• 11/18/2024

Fish species' occurrence is influenced by environmental conditions across multiple spatial and temporal scales. Alteration to stream systems has the potential to affect occurrence patterns of fish species. Stream systems of the North America Great Plains face threats originating from climate change and anthropogenic activities resulting in negative implications for many fish species. The Sandhills Ecoregion, Nebraska is considered one of the largest intact grasslands in North America, and thus may experience fewer threats than surrounding areas. Stream systems of the Sandhills Ecoregion are home to 12 fish species of greatest conservation need (SGCN). Little context exists regarding the environmental associations of fish SGCN and, to our knowledge, no studies have focused evaluations on how fish assemblages have changed through time in the Sandhills Ecoregion. Therefore, this study sought to 1) identify the multiscale environmental associations of fish SGCN inhabiting Sandhills Ecoregion streams using occupancy models and 2) assess how fish assemblages have changed since statewide sampling in 1939-1941 using retrospective analyses. We sampled 95 sites for fish assemblages and environmental data throughout the Niobrara River and Elkhorn River drainages of the Sandhills Ecoregion. We also built a database of historical fish occurrence since 1939 for the Niobrara River and Elkhorn River drainages of the Sandhills Ecoregion. Occupancy models constructed using contemporary survey data highlighted that fish SGCN occurrence is low. We also identified that fish SGCN occurrence is mediated by hierarchical multiscale environmental factors. Common variables included in top-ranked models were depth-to-groundwater, index of watershed integrity, stream slope, and proportion of predators. We also identified that assemblages of the Sandhills Ecoregion have exhibited shifts in the relative frequencies of some fish species, but have experienced limited shifts in relative frequencies at the functional trait level. Results from this study provide managers with a rigorous baseline of fish species occurrence in the Sandhills Ecoregion from which to compare to future assessments and may be useful when determining conservation actions.

• Dissertation Defense
• 07/26/2024

Mountain lions (Puma concolor) have been studied extensively throughout their wide geographic distribution in the Western Hemisphere, but most research has been conducted at relatively small spatial scales. We used GPS telemetry data contributed by researchers in 16 study areas throughout California to advance understanding of mountain lion spatial ecology. First, we investigated multi-scale resource selection of mountain lions relative to spatially varying risk of intentional human-caused mortality associated with livestock depredation management. We show that individuals that proactively avoided mortality risk when selecting home ranges were able to relax their avoidance of risk when making resource selection decisions within their home ranges. Our analysis also demonstrates that functional responses in resource selection provide a quantitative link between coarse and fine-scale resource selection decisions made by individual animals. Second, we evaluated movement-based resource selection of subadult mountain lions during dispersal, which is the primary mechanism that maintains gene flow between populations. Our results support the hypothesis that anthropogenic landscape features act as barriers to movement that limit demographic and genetic connectivity between populations, elucidating behavioral mechanisms underlying the observed genetic structure between California mountain lion populations. However, our results also suggest that preservation of even relatively small patches of natural habitat and implementing road-crossing infrastructure should enhance connectivity. Third, we investigated intrinsic, ecological, and anthropogenic factors influencing home range size of mountain lions along a statewide gradient of landscape productivity and human disturbance. Our results indicate that home range size is influenced by the abundance and distribution of prey in relatively undisturbed landscapes, whereas anthropogenic features create fragmentation and barrier effects that influence home range size in developed regions. Our work advances understanding of responses of mountain lions to mortality risk from the leading mortality cause in California, behavioral mechanisms of reduced connectivity between populations, and the influence of natural and anthropogenic factors on space use. Management and conservation informed by empirical research will contribute to promoting long-term viability of mountain lions in southern California and along the central coast, which face challenges similar to those of large carnivores around the globe associated with human-wildlife conflict, habitat loss, and fragmentation.

• Thesis Defense
• 07/26/2024

Invasive Carp species: Silver Carp Hypopthalmicthys molitrix, Bighead Carp Hypopthalmicthys nobilis, Grass Carp Ctenopharyngodon idella, and Black Carp Mylopharyngodon piceus have both potential and realized abilities to negatively impact native species. Specifically, Bighead Carp and Silver Carp as filter-feeders have been theorized to be detrimental not only to adult filter-feeding species, but to many fish which rely on plankton and algae in their early-life stages. The impact of Invasive Carp on the overall fish community remains underexplored. The fish communities below Gavins Point Dam (Invasive Carp present) and Fort Randall Dam (Invasive Carp absent) afford the opportunity to directly compare recent sampling with historic sampling done in these same reaches. This study set out to determine if there is a difference between the contemporary Gavins Point Dam and Fort Randall Dam fish communities, and whether that difference is attributed to Invasive Carp presence. Differences in the fish communities below Gavins Point Dam and Fort Randall Dam could not be directly tied to Invasive Carp presence, but decreased condition of Bigmouth Buffalo Ictiobus cyprinellus in the presence of Invasive Carp indicates that Silver Carp and Bighead Carp may be negatively impacting native species. This study also found no evidence of young-of-year and few age-1 Invasive Carp in the tailrace of Gavins Point Dam. This may allow a unique opportunity to implement barriers to Invasive Carp immigration to the tailrace, thereby decreasing their presence at the furthest upriver point of their invasion.

• Thesis Defense
• 07/23/2024

As species respond to changing climate, distributions and abundances may shift and alter species interactions. Hybridization, a relatively widespread phenomenon becoming more common with climate change, can have detrimental effects on population growth rates and genetic integrity. Beneficial effects due to the introduction of advantageous alleles and increased genetic diversity may result from hybridization as well. Species may also accrue fitness costs associated with changing climates if mismatches occur between environmental variables and phenotypes. The gray-headed chickadee, Poecile cinctus lathami, is an extremely rare songbird that has experienced marked declines in recent decades within its restricted distribution in Alaska and northwestern Canada. The widespread boreal chickadee, Poecile hudsonicus, has conversely become more locally abundant. We investigated two hypotheses of mechanisms – hybridization and environmental change – that may have contributed to the apparent rapid decline of the gray-headed chickadee and influx of boreal chickadee using mitochondrial and reduced representation nuclear DNA sequence data. We analyze historical specimens of both species and contemporary boreal chickadees to investigate the occurrence of hybridization and trends of abundance and interspecific gene flow. We also test for gene-environment associations using historical, present, and future climate data sets to explore the trajectory of boreal chickadee adaptation to their local environment. We detect evidence of hybrids backcrossing to boreal chickadee populations prior to recent declines, and signatures of later-generation hybrids among both historical and contemporary boreal chickadees. We find that boreal chickadee genetic isolation-by-environment exceeds isolation-by-distance. Further, we identify temperature and precipitation bioclimatic variables which have strong associations with allelic composition, and predict areas with the highest risk of environmental-genetic mismatch due to climate change. This study identifies hybridization as playing a role in gray-headed chickadee declines despite the inability to sample any individuals today, and provides evidence that environment-genetic mismatches may occur for boreal chickadees as a result of climate change across areas of sympatry and allopatry.

• Thesis Defense
• 07/17/2024

The Nebraska Sandhills are home to Nebraska’s top agriculture industry, beef cattle production, and various wildlife and plant species. The overlap of agriculture and natural resources in this area makes it challenging to maintain a profitable agriculture operation while minimizing negative impacts on the area’s natural resources. However, with the development of precision livestock management technology, new conservation methods are becoming accessible to ranchers that can aid in optimizing rangeland profitability and habitat conservation. Our study occurred during the 2023 summer grazing season at the University of Nebraska Lincoln’s Gudmundsen Sandhills Research Laboratory. Two research studies were conducted to explore the effects of virtual fencing on beef cattle stress and examine how the Sandhills topography may influence wildlife species richness and abundance. Livestock producers who consider adopting new precision management technology, such as virtual fencing, hold animal welfare as a top priority. The first study examines how virtual fencing influences heart rate (HR) changes in cattle fitted with virtual fencing collars. The results indicated that cattle did not experience any significant increases in HR due to audio or shock cues, and the virtual fence did not appear to cause acute stress on the cattle. The second study aimed to identify critical wildlife habitats in rangeland landscapes and the factors that influence wildlife habitat selection. We explicitly focused on three main topographical areas spread throughout the ranch: dry valleys, dune tops, and wetlands/sub-irrigated meadows. The results showed no significant difference in species richness. However, there was a significant difference in overall species abundance amongst the three topographic areas, with abundance being greater in the sub-irrigated meadows. By integrating precision technology into livestock management and conservation practices, ranchers can create a sustainable and prosperous future for their livestock and the local ecosystem for future generations.

• Thesis Defense
• 07/15/2024

The grasslands of the Northern Great Plains are social-ecological systems that have undergone many changes since the start of European settlement. The sacred social-ecological relationships Indigenous people nurtured with the land were harmed as colonialism displaced and persecuted their communities, which degraded social-ecological resilience and shifted grasslands to a new state. The cultural and natural burning that evolved with migratory grazers on grasslands was also disrupted through sedentary agriculture, Western land tenure, fire suppression, and Indigenous exclusion. These changes further harmed social-ecological resilience in grasslands and exposed them to woody encroachment, invasive species, and increasing wildfires. For those reasons, my graduate research focused on assessing, restoring, and centering evolutionary and Indigenous social-ecological relationships for advancing social-ecological resilience in the Northern Great Plains grasslands. Since the mid-20th century, there has been an increase in Western studies focused on improving the social-ecological resilience of grasslands by restoring social-ecological relationships. Patch-burn grazing is being employed to mimic the ancestral coupling of fire and grazing that shaped grasslands, but additional information is still needed to understand how to best apply it. I performed a study in the Sandhills of Nebraska to assess the potential of Patch-burn grazing for restoring grassland social-ecological relationships and resilience by comparing it to that of Rotational grazing. Through vegetation and bird surveys, my research examined the impacts of these practices on vegetation structure, biodiversity, and heterogeneity and bird diversity and functional groups. The results indicate that each treatment contributes to grassland resilience in different manners. Patch-burn grazing caused higher forb and vegetation diversity, which should support more niches and ecological functions. While standing biomass did not vary by treatment, Rotational grazing had higher vegetation, indicating its potential for production, and the practice had more plot-level heterogeneity while both treatments contributed to patch-level variability, which has potential for supporting biodiversity, wildfire mitigation, and resilience. Rotational grazing also increased invertivore birds and burning increased ground nesters while grazing reduced omnivore birds and grassland obligate birds that are two functional groups of concern for grassland resilience. Grazing and burning also decreased functional diversity while natural heterogeneity supported it. The overall impacts of Patch-burn grazing indicate that it caused similar production levels as Rotational grazing while supporting heterogeneity and more diversity. Because both practices contributed to grassland resilience but with differing impacts, the decision to use one or the other is dependent on management goals and priorities. Furthermore, while Indigenous social-ecological relationships shaped the social-ecological resilience of grasslands and are also essential for restoring them, there has been a historical lack of Western research focused on understanding and supporting Indigenous priorities and resilience. I collaborated with Indigenous leaders to assess and center social-ecological relationships, resilience, and priorities of Indigenous people in Eastern Nebraska. Guided by Indigenous and Western sciences, I conducted semi-structured interviews with Indigenous leaders to center their social-ecological relationships and identify the changes that could support and restore the social-ecological resilience of their communities. Responses indicated that it is important to challenge ongoing settler colonialism that continues to harm Indigenous people and grasslands through oppression, pollution, and exploitation. Participants prioritize improving social-ecological resilience for all people by restoring their ancestral relationships with their communities, cultures, and grasslands. Overall, this interdisciplinary study has potential to inform efforts to advance resilience in grasslands in the Northern Great Plains. It highlights the complex impacts of grassland management practices on biodiversity and heterogeneity while showing the potential of Patch-burn grazing for maintaining production and advancing resilience. The study also centers how the leadership of Indigenous people is important for improving grassland social-ecological resilience as their cultures hold ancestral knowledge for restoring evolutionary social-ecological relationships and supporting equitable decision-making that benefits all communities in the Northern Great Plains.

• Thesis Defense
• 04/16/2024

Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively bigheaded carp) have invaded tributaries to the Missouri River and Platte River in Nebraska, USA. Information pertaining to efficient sampling protocols for assessing bigheaded carp populations as well as benefiting removal efforts is needed. Herding is a method used to increase the capture efficiency and detection probability of adult bigheaded carp by simultaneously using active and passive sampling gears. During June-July 2023, four herding techniques were assessed regarding their ability to elicit directional movement past an enclosure gate. The combination of sound and electrofishing resulted in the highest mean number of bigheaded carp successfully herded, followed by electrofishing, sound, boat and motor only, and the control. Mean depth was shown to influence herding effectiveness and exhibited a positive relationship. During the summer of 2024, boat electrofishing and herding with gill nets were conducted on three tributaries of the Missouri River and one tributary of the Platte River and compared based on capture efficiency and cost-effectiveness. A total of 6,205 bigheaded carp were collected, with herding resulting in the capture of 2.8 times more bigheaded carp than electrofishing. Herding (437.3 fish/hr) had a higher mean catch-per-unit-effort (CPUE) than electrofishing (155.0 fish/hr) when accounting for gear effort (i.e., run time). However, electrofishing (39.0 fish/person-hr) had a greater CPUE than herding (20.1 fish/person-hr) with the inclusion of overall effort (i.e., labor hours and crew size). In achieving an equivalent weekly catch, electrofishing was more cost effective than herding. The results of this study will provide managers, researchers, and stakeholders knowledge regarding efficient and cost-effective sampling strategies for invasive bigheaded carp that enable assessments of presence and population status as well as provide control options for population reduction and potential removal.