Theses and Dissertations

Permanent URI for this collection

https://hdl.handle.net/10217/100425

Of special note are theses cited in James R. Meiman's Little South Poudre Watershed and Pingree Park Campus (Colorado State University, College of Forestry and Natural Resources, 1971).

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Now showing 1 - 9 of 9

Open Access
Effects of invasive species on native herpetofauna and pond communities in urban environments
(Colorado State University. Libraries, 2022) Crone, Erin Renee, author; Preston, Daniel L., advisor; Angeloni, Lisa, committee member; Bailey, Larissa, committee member; Herrick, Bradley, committee member
Urban environments can provide high quality habitat for native species, yet these environments are also prone to species invasions via numerous introduction pathways. Invasive species may affect communities through multiple mechanisms including ecosystem engineering, predator-prey interactions, and resource competition, so isolating individual effects can be challenging. Further, urban environments commonly host multiple invasive species, which may interact with one another and amplify effects on native species. Despite their potential effects, however, the roles of invasive species in urban communities are often poorly understood. For example, the city of Madison, Wisconsin, USA is home to multiple invasive species, including jumping worms (Amynthas spp.), goldfish (Carassius auratus), and Chinese mystery snails (Cipangopaludina (=Bellamya) chinensis), but little is known about the community effects of these species. Jumping worms are non-native invasive earthworms that may act as ecosystem engineers in leaf litter habitat and potentially provide an abundant novel prey resource to native predators. Invasive goldfish and mystery snails have been widely introduced through aquarium trading and are known to co-occur in urban ponds. In the first study, we used a mesocosm experiment, laboratory feeding trials, and nonlethal stomach contents surveys to assess effects of invasive jumping worms on microhabitat and trophic interactions of native herpetofauna predators. We found that jumping worms reduced leaf litter biomass but did not influence soil conditions or survival of American toad (Anaxyrus americanus) metamorphs. Our results revealed that jumping worms are viable prey for native herpetofauna, especially common garter snakes (Thamnophis sirtalis), but may be challenging to capture due to defensive behaviors. In the second study, we used a mesocosm experiment to test for facilitative or antagonistic interactions between goldfish and mystery snails, and to examine individual and combined effects of goldfish and mystery snails in urban pond communities. We found evidence that goldfish facilitate invasive mystery snails, and that goldfish drive shifts in community composition and food web structure through trophic cascades. Comparatively, mystery snails had limited effects in the experimental community. Overall, our studies emphasize the diversity of roles invasive species can play in communities as ecosystem engineers, prey, predators, or competitors, and that their effects on native species are dependent on these roles. Broadly, our findings highlight the value of understanding invasive species effects in urban environments to direct management and support native species conservation.
Open Access
Habitat use and conservation implications for Akikiki (Oreomystis bairdi) and Akekee (Loxops caeruleirostris), two endangered Hawaiian honeycreepers
(Colorado State University. Libraries, 2014) Behnke, Lucas Alan Hallman, author; Goldstein, Liba, advisor; Crampton, Lisa, committee member; Angeloni, Lisa, committee member; Theobald, David, committee member
Limited resources for biodiversity conservation warrant strategic science-based recovery efforts, particularly on islands, which are global hotspots of both endemism and extinction. The diverse assemblages and the extreme isolation of the islands of the Hawaiian archipelago make them a unique laboratory for development of a coherent strategy for recovery of rare species and for large-scale systems conservation efforts. The Akikiki (Oreomystis bairdi) and the Akekee (Loxops caeruleirostris) are critically endangered honeycreepers endemic to the Hawaiian island of Kauai. Recent declines and range contraction spurred this study, the first systematic scientific investigation of these little known species. I conducted occupancy sampling for Akikiki and Akekee and vegetation surveys at plots within five study areas on the Alakai plateau of Kauai to assess range-wide occupancy and habitat use. Occupancy rates for both species increased from west to east along the plateau (Akikiki: Ψ = 0.02 ± 0.07 to 0.55 ± 0.21 Akekee: Ψ = 0.03 ± 0.10 to 0.53 ± 0.33), but were low throughout the ranges of both species. Canopy height was correlated with occupancy for both species, which suggests the damage done by hurricanes in 1982 and 1992 may be restricting these birds to the most intact forest remaining. Vegetation surveys revealed several key differences in forest composition and structure between areas, indicative of broader changes occurring across the plateau. Invasive plants such as Himalayan ginger (Hedychium gardnerianium) were dominant in the western portion of the plateau, where there was a corresponding decline in native plant cover. Conversely, ground disturbance by feral ungulates was higher in more eastern native-dominated plots. These results highlight the need to control ungulates and limit habitat degradation in the regions with the highest occupancy of Akikiki and Akekee. Without significant investment to address these threats and protect and restore suitable habitat for these species, it is unclear how long these birds will persist.
Open Access
Home range estimates, habitat selection, and nesting behavior of Ferruginous Hawks (Buteo regalis) in western Wyoming
(Colorado State University. Libraries, 2024) Ramirez, Sarah Kathleen, author; Pejchar, Liba, advisor; Koons, David, committee member; Angeloni, Lisa, committee member
Oil and gas development has the potential to negatively impact wildlife, but the consequences for some raptor species are less well understood. Ferruginous Hawks could be particularly susceptible to negative effects due to their large habitat requirements and sensitivity to anthropogenic disturbance. Given the rapid expansion of oil and gas development in many parts of the range of Ferruginous Hawks, it is critical to evaluate habitat use in both a pre-construction and post-construction environment. Understanding selection of habitat resources and nest sites, as well as the factors that contribute to home range estimates, nest success and nest productivity could help inform efforts to mitigate against potential negative effects of land use change. In my first chapter, I aimed to investigate factors associated with breeding Ferruginous Hawk home range estimates and habitat selection in a landscape slated for energy development. In a sagebrush-steppe study site in western Wyoming, I captured breeding hawks and used radio and satellite-telemetry to collect location data, estimate home range estimates, and model habitat selection. Home range estimates were smaller for females and hawks with egg-laying breeding status, and larger with increasing numbers of producing wells. Ferruginous Hawks selected habitat with high terrain ruggedness, low shrub cover, and areas closer to primary prey, and avoided areas with high density of wells. The relationship between lagomorph density and distance to development was dependent on scale. My findings show that home range estimates are smaller in my study relative to other parts of the species' range, and that future energy development is likely to reduce habitat quality and availability for Ferruginous Hawks. In my second chapter, I investigated the factors associated with nest site selection, success, and productivity in the same study site in western Wyoming. I used an existing dataset on nest site locations, nest success, and productivity, and collected new data on these response variables between 2019 and 2023. I used a resource selection function model (RSF) to evaluate nest site selection and used generalized linear mixed models (GLMMs) to evaluate nest success and productivity. Ferruginous Hawks selected nest sites in developed-open space landcover (e.g., areas cleared of vegetation with little or no infrastructure), higher topographic position index (TPI), and in closer proximity to producing wells (km). In contrast, breeding hawks avoided nest sites in areas with higher densities of producing wells (per km2) and more shrub cover (%). Nest success and productivity of egg-laying pairs was positively associated with artificial nesting platforms (ANPs) and negatively associated with anthropogenic structures and rocky outcrops, developed-open space landcover, TPI and year. These findings suggest that Ferruginous Hawks may be subject to an ecological trap when they nest on anthropogenic structures, but that ANPs are a potentially viable tool for mitigation.
Open Access
How does rock-ramp fishway surface texture affect the passage success of small-bodied Great Plains fishes?
(Colorado State University. Libraries, 2021) Brittain, Cole, author; Myrick, Christopher A., advisor; Kanno, Yoichiro, committee member; Angeloni, Lisa, committee member
The waterways of the North American Great Plains have experienced extensive fragmentation from instream structures and intermittency caused by excessive dewatering. The modifications to these waterways include numerous barriers that prevent the upstream movement of fish. State and federal resource management agencies have turned to fish passage structures to restore connectivity. However, the passage efficiency of current structures may be limited for native small-bodied fish species by a lack of information on how fish swimming behavior and performance are affected by the key fishway design parameters of slope, length, and texture. Recent research has provided more information on fishway slope and length, and identified texture of the surface between the larger roughness elements as an area needing more investigation. We evaluated the effects of four surface textures (smooth; 1 – 2 mm diameter coarse sand; 6 – 10 mm diameter pea gravel, and; 19 – 31 mm diameter small cobble) on the passage success of three native small-bodied fish species, Arkansas Darter (Etheostoma cragini), Flathead Chub (Platygobio gracilis), and Stonecat (Noturus flavus) using a 6.1-m long experimental rock ramp fishway set at a 6% slope. Our results demonstrated that passage success for the Arkansas Darter increased from 0% on the smooth substrate to 32.2% for the small cobble substrate. A similar pattern was observed for the Stonecats, with an increase in passage success from 31.1% on the smooth substrate to 86.7% on the small cobble substrate. Flathead Chub passage success was independent of substrate treatment and exceeded 90% in all cases. Our study suggests that the use of more highly textured substrates is a viable option for increasing the passage success of small-bodied fishes that otherwise do not perform well on rock ramp fishways.
Open Access
Intraspecific variation in reproductive ecology and success of a keystone stream fish, bluehead chub
(Colorado State University. Libraries, 2019) Kim, Seoghyun, author; Kanno, Yoichiro, advisor; Angeloni, Lisa, committee member; Bestgen, Kevin R., committee member; Winkelman, Dana L., committee member
To view the abstract, please see the full text of the document.
Open Access
Introduction and management of Myxobolus cerebralis-resistant rainbow trout in Colorado
(Colorado State University. Libraries, 2013) Fetherman, Eric R., author; Winkelman, Dana, advisor; Bailey, Larissa, committee member; Huyvaert, Kathryn, committee member; Angeloni, Lisa, committee member
To view the abstract, please see the full text of the document.
Open Access
Measuring the effects of ammonia and dissolved oxygen on juvenile burbot (Lota lota) growth and survival
(Colorado State University. Libraries, 2021) Vaage, Ben, author; Myrick, Christopher, advisor; Angeloni, Lisa, committee member; Clements, Will, committee member
Burbot, Lota lota are a candidate species for commercial aquaculture because of their palatability and optimal growth at temperatures similar to those used in freshwater trout aquaculture. However, data on burbot environmental tolerances and requirements are sparse, especially with reference to water quality parameters relevant to aquaculture, such as un-ionized ammonia (UIA) and dissolved oxygen concentrations. First, we used a two-phased approach to evaluate the effects of un-ionized ammonia on the growth and survival of burbot. We measured the acute toxicity of ammonia to juvenile burbot (mean SL: 144 ± 6 mm; mean wet weight: 27.3 ± 3.4 g) and calculated a 96-hr LC50 of 0.58 mg·L-1 UIA. We then measured the 60-d growth, food consumption rate, and performance of burbot (mean initial SL: 190 ± 6.9 mm; mean initial weight: 67.0 ± 4.5 g) reared in 0.00, 0.03, 0.06, 0.12, or 0.19 mg·L-1 UIA using a 20-tank flow-through system under optimal temperature (14.7°C) and dissolved oxygen (DO > 80% saturation) conditions. Elevated ammonia concentration significantly reduced daily food consumption and subsequent growth. Fish exposed to 0.03 and 0.06 mg·L-1 UIA showed temporal acclimation to UIA, achieving food consumption and growth rates on par with control fish after 30 days of exposure. The estimated effective UIA concentrations for 10 and 20 percent reductions in growth (EC10 and EC20) based on our data are: EC10 = 0.03 ± 0.006 mg·L-1 and EC20 = 0.050 ± 0.004 mg·L-1. We recommend rearing burbot under conditions that keep UIA levels ≤ 0.03 mg·L-1 based on our finding that above 0.03 mg·L-1 cause measurable reductions in growth rate. Following the ammonia studies, we exposed juvenile burbot (19.5 ± 2.2 g) to five dissolved oxygen concentrations (5.0, 5.8, 6.6, 7.4, and 8.3 (control) mg·L-1) for 9 weeks at 15°C. Variability was high in all treatments, and food consumption and growth rates did not differ among DO levels, although fish at 8.3 mg·L-1 grew ca. 29% larger than those at 5.0 mg·L-1. We also measured short-term hypoxia tolerance and resting routine oxygen consumption rates (MO2) of burbot that had been chronically acclimated to the same DO concentrations. Burbot acclimated to 8.3 mg·L-1 lost equilibrium (LOEcrit) at a significantly higher concentration (1.85 ± 0.33 mg·L-1) than that of the 7.4 and 6.6 mg·L-1 acclimated fish (1.50 ± 0.37 and 1.49 ± 0.27; respectively), while all other groups were intermediate (1.67 ± 0.28). The MO2s were not statistically distinguishable among acclimation groups (p-value = 0.25), but MO2 trended lower with decreasing DO concentrations typifying an oxyconforming species. In summary, juvenile burbot are quite tolerant to DO concentrations down to 5.0 mg·L-1. We recommend rearing burbot at DO concentrations > 7.0 mg·L-1 and that minimum short-term DO concentrations be kept > 4.0 mg·L-1in culture environments where multiple stressors may be present.
Open Access
Triploid walleye: a new frontier for nonnative predator management in the West
(Colorado State University. Libraries, 2022) Farrell, Collin J., author; Johnson, Brett, advisor; Myrick, Christopher, advisor; Hansen, Adam, committee member; Angeloni, Lisa, committee member
To view the abstract, please see the full text of the document.
Open Access
Understanding and mitigating coyote predation on black-footed ferrets
(Colorado State University. Libraries, 2019) Windell, Rebecca Much, author; Breck, Stewart, advisor; Angeloni, Lisa, committee member; Bailey, Larissa, committee member; Eads, David, committee member
Coyotes (Canis latrans) kill more livestock than any other mammal in the U.S. and can be important predators of vulnerable native fauna. In prairie ecosystems, coyotes are the primary predator of endangered black-footed ferrets (Mustela nigripes; hereafter, ferret), where coyote predation can significantly hamper ferret recovery efforts. To better understand coyote predation on ferrets we used remote wildlife cameras, occupancy models, and overlap of circadian activity patterns to investigate multiple abiotic, biotic, and temporal factors hypothesized to influence coyote use of prairie dog colonies, and by proxy coyote-ferret interactions. We first assessed coyote preferences between prairie dog colonies and surrounding available grasslands and found coyotes used prairie dog colonies nearly twice as much as surrounding grasslands. Next, we investigated biotic and abiotic factors that may influence coyote use and frequency of use on prairie dog colonies. We found high coyote use across our study area, but frequency of use varied across prairie dog colonies and was higher in areas of high badger occurrence. Badgers and coyotes are known to form hunting associations and high overlap between coyote and badger activity patterns in our study further supported spatial use patterns revealed by our occupancy analysis. Strong interspecific competition and patterns of resource selection between badgers and ferrets have been documented in previous studies, and as a result, our study suggests that coyote attraction to badgers may be the principal influence on coyote-ferret interactions. To mitigate coyote predation on ferrets we excluded coyotes from ferret occupied areas with a new non- lethal tool, coyote fladry (hereafter; fladry), and rigorously assessed fladry's effectiveness for future use in both ecological and agricultural scenarios. Again using wildlife camera data, we evaluated coyote fladry with multi-season occupancy models, where we estimated probabilities of use (i.e., occupancy), avoidance (i.e., extinction), attraction (i.e., colonization), and activity (i.e., detection) in response to fladry. Our results indicate fladry reduced coyote use and activity within protected areas for at least 60 days; however, coyotes also increased activity around, and were attracted to, the periphery of fladry exclosures, suggesting fladry may function in a way that is counterintuitive to management expectations. Occupancy models permit robust evaluation of nonlethal tools beyond binary terms of success and failure and provide valuable additional information, such as the behavioral responses of carnivores to these tools. Coyote fladry does not deter badger use of protected areas, and given the importance of badgers in predicting coyote use of colonies, future efforts to reduce coyote predation on ferrets should compare the effectiveness of tools that exclude both badgers and coyotes to our study's results.

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Browsing Theses and Dissertations by Author "Angeloni, Lisa, committee member"

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