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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Open Access
Abundance, survival, and breeding probabilities of the critically endangered waved albatross
(Colorado State University. Libraries, 2013) Street, Phillip A., author; Doherty, Paul F., advisor; Huyvaert, Kathryn P., advisor; Cafaro, Philip, committee member
To view the abstract, please see the full text of the document.
Open Access
Advancing the science and practice of conserving hihiwai: using ecology and traditional ecological knowledge to identify and overcome threats to an endemic Hawaiian gastropod
(Colorado State University. Libraries, 2021) Ka'awa-Gonzales, Kiloaulani E. C., author; Pejchar, Liba, advisor; Clements, William H., advisor; Niemiec, Rebecca, committee member
Aquatic gastropods are valuable indicators of stream health in tropical ecosystems globally. Sustaining gastropods on islands is particularly important because these species provide numerous ecosystem services such as water purification, nutrient cycling, mediating the transfer of carbon through food webs, and providing sustenance for people. Hihiwai (Neritina granosa) is an amphidromous snail that was used as a subsistence food source in ancient times by Native Hawaiians and is still harvested today. Yet, this species is of conservation concern and both the ecological factors associated with its density and distribution as well as the socio-cultural knowledge associated with this species are largely unknown. Bridging Traditional Ecological Knowledge (TEK) and western science, which requires valuing indigenous knowledge and leadership and incorporating these ways of knowing into conservation science and practice, is an effective strategy to address this paucity of information in local and Indigenous communities. TEK is particularly important on islands where indigenous communities steward their often imperiled cultural and natural heritage. Evaluating the factors contributing to hihiwai loss and recovery using a combination of western science and TEK could serve as a model for Indigenous and local communities at the marine/freshwater interface globally. To address these knowledge gaps, I surveyed four streams on the Hawaiian Islands of Molokai and Maui to 1) determine which characteristics of stream systems are associated with Hihiwai population density across age classes, and 2) evaluate the size distribution of adult hihiwai as a function of stream characteristics. Specifically, I used stratified random quadrat sampling to assess hihiwai densities along an elevational gradient in streams with (n = 2) and without (n = 2) diversions. I collected data on stream characteristics such as width, depth, velocity, discharge, temperature, shading, and substrate. I found that hihiwai recruits, juveniles and adults were more abundant in diverted streams, all size classes and adult length were positively associated with stream depth, adult hihiwai were more likely to occur at higher elevations, and there was an inverse relationship between adult size and density, with larger hihiwai more likely to occur where adults were least abundant. In parallel with the stream surveys, I conducted semi-structured interviews with 20 local community members on Molokai to examine how traditional ecological knowledge and local experience can be used to better understand the ecology and cultural value of hihiwai, and to engage local communities in the conservation of this species and its habitat. Three major takeaways were identified as relevant for understanding the drivers, impacts, and next steps for hihiwai conservation: 1) community members believe that hihiwai populations are decreasing due to a combination of direct (overharvesting, water diversions) and indirect (higher stream temperatures, invasive plants) anthropogenic effects; 2) The perceived decrease in hihiwai abundance on Molokai has resulted in fewer opportunities for local people to connect with each other and spend quality time (eating and picking hihiwai), a loss of historic knowledge of hihiwai and cultural identity, and has disrupted the transmission of cultural and ecological knowledge to the next generation; and (3) Community members emphasized the need for informed local conservation leaders who represent the interests of the local Molokai people to guide and enforce hihiwai and Hawaiian stream management. Although community perceptions of whether bottom-up or top-down management strategies would be more effective were mixed, there is a general consensus that a change in values toward hihiwai harvest and possible harvest limits are needed to ensure healthy hihiwai populations in the future. My findings from this cross disciplinary study highlight the overlap, as well as the novel information that can emerge from integrating ecological and social research. Bridging the gap between western ecological science and TEK through local community collaboration will be critical for developing effective management plans that ensure ecological and cultural sustainability of hihiwai in Hawaii.
Open Access
An experimental test of intra- and inter-specific competition between invasive western mosquitofish (Gambusia affinis) and native plains topminnow (Fundulus Sciadicus)
(Colorado State University. Libraries, 2022) Lewis, Samuel, author; Kanno, Yoichiro, advisor; Salerno, Jonathan D., committee member; Sanderson, John S., committee member; Preston, Daniel L., committee member
1. Invasive species are a major threat to freshwater conservation. Species coexistence in invaded habitats depends on the relative strength of intra- versus inter-specific competition, where inter-specific competition from invasive species to native species is often stronger than intra-specific competition, jeopardizing their coexistence.2. In this study, I conducted a laboratory experiment to test for the relative competitive strength between native plains topminnow (Fundulus Sciadicus) and invasive western mosquitofish (Gambusia affinis) at 16, 22, and 28 °C. Data were analyzed using the isodar theory, which assumes that animals are ideally distributed to maximize their fitness and thus their distributions measure the quality and quantity of habitat patches. This was supplemented by behavioral observations of intra- and inter-specific competition. 3. Contrary to my predictions, I did not find evidence that competition was asymmetrical from the invasive mosquitofish to the native plains topminnow. Instead, more individuals occupied their shared preferred habitat (a slow-moving pool) in sympatry compared to allopatry, and the isodar analysis demonstrated that intra-specific competition was significantly stronger than inter-specific competition at all temperature levels. This analysis of habitat selection was corroborated by behavioral observations that aggression was most frequent between plains topminnow in sympatry. 4. This study indicates that aggression might not always be the key mechanism of invasion, even for one of the most successful aquatic invasive species widely known for their aggressive behavior. In mosquitofish, other ecological traits such as fast reproductive cycle and tolerance to a wide range of environmental conditions might be responsible for their invasion success globally. This suggests that mosquitofish may not be a driver in native species declines, but rather an opportunistic invader in degrading ecosystems.
Open Access
Arctic Char Salvelinus alpinus can enhance fisheries in reservoirs with trophic constraints
(Colorado State University. Libraries, 2014) Olsen, Devin M., author; Johnson, Brett, advisor; Boone, Randall, committee member; Myrick, Christopher, committee member; Lepak, Jesse, committee member
The 20th century was a period of rapid reservoir construction in the western United States. Initially, many of these reservoirs hosted productive recreational fisheries for introduced salmonids, but then waned from oligotrophication, dam operations, and the effects of introduced opossum shrimp Mysis diluviana. Managers have sought alternative fish species that could withstand these trophic constraints. In 1990 the state of Colorado introduced Arctic Char Salvelinus alpinus into Dillon Reservoir hoping they would prey on Mysis and produce a valuable "boutique fishery". My study investigated the outcomes of this introduction. I found that the introduction resulted in a reproducing population, creating one of the only public fisheries for Arctic Char in the lower 48 states of the USA, and the southernmost population in the world. Arctic Char diet was composed primarily of Mysis shrimp, and their growth was among the fastest of lacustrine populations worldwide. While bioenergetics simulations showed that approximately 3-6 times as many Arctic Char would need to be stocked annually to effectively control Mysis shrimp, Arctic Char did channel energy formerly sequestered in Mysis into desirable recreational fish biomass. Despite this desirable ecosystem service, the stocking program is paradoxical. In an era when nonnative species comprise a primary threat to aquatic biodiversity, condoning new introductions is concerning. However, in many human-dominated environments such as reservoirs, exotic fishes already comprise the majority of species. Fishery managers are left with the problem of choosing relatively innocuous strategies that can still provide recreational benefits in systems plagued by a variety of anthropogenic stressors.
Open Access
Assessing the swimming and jumping performance of Wyoming fishes with implications for fishway design
(Colorado State University. Libraries, 2024) Garvey, Chase, author; Myrick, Christopher A., advisor; Kanno, Yoichiro, committee member; Wohl, Ellen, committee member
To successfully begin to solve the complex problems facing native fish conservation efforts, we need to seek a deeper understanding of the fish that inhabit the communities that we hope to conserve. With regards to the issue facing the fragmentation of our lotic ecosystems, and the effects that dams and similar structures can have on fish communities, fishways are a common tool used to restore the connectivity of streams by allowing the uninhibited passage of fish. In these experiments we studied the swimming and jumping abilities of Hornyhead Chub (Nocomis biguttatus), Bigmouth Shiner (Notropis dorsalis), Iowa Darter (Etheostoma exile), and Brook Stickleback (Culaea inconstans) in order to provide fisheries managers with criteria for fishway design that will allow the passage of desirable target species, and potentially block the spread of invasive Brook Stickleback. We did this by testing the jumping abilities of each species at various temperatures using artificial waterfalls. After testing groups of fish at various waterfall heights, we used logistic regression to predict the probability of individual fish passage under various conditions. To test the swimming ability of each species, we used swim tunnels to determine the maximum swimming velocity of each species, and estimate their endurance at various swimming velocities. Our results show that a vertical barrier greater than 15 cm will block the upstream movement of nearly all individual Hornyhead Chub. Heights greater than 8.4 cm will block the upstream passage of Bigmouth Shiner, and barriers taller than 6.0 cm will block the upstream passage of Iowa Darter and Brook Stickleback. Given this information, if vertical drops and pool designs were to be incorporated into fishways designed for these species, drops between fishway pools should remain within these thresholds if successful passage is to be achieved. The results of the swimming performance experiments show that each species' swimming abilities are unique relative to their raw maximum swimming abilities and overall endurance. The problem facing engineers and biologists is that many different species that make up these communities are unique, and have characteristics that pose specific challenges or advantages to assisting their movements. Additionally, fisheries scientists must remain cognizant that fishways that allow native fish movement will likely allow the movement of non-target species (including potential invasives) present in the same systems. Managers must balance the trade-offs between restoring native ecosystems and protecting areas that have not been invaded.
Open Access
Avian conservation and ecology in northern Vietnam
(Colorado State University. Libraries, 2009) Vu, Thinh Tien, author; Doherty, Paul F., Jr., advisor; Huyvaert, Kathryn, advisor
Due to the rapid rate of biodiversity loss in Vietnam conserving the avian biodiversity is a contemporary issue of concern and my dissertation was aimed at several issues focused on avian conservation. Recently, the number of non-native tree plantations has increased but the conservation potential of such plantations remains unknown. In Chapter 1, I estimated bird species richness to be highest in mature natural forest, lower in second-growth natural forest, and lowest in pine plantation. I suggest that natural forest types should receive priority for conservation in Vietnam. In Chapter 2, I compared bird movement over a paved road (6-8m wide) and within forest interior plots. The probabilities of approaching the playback for ground species at the road site were lower than those in the forest interior. The road seems to moderately affect the ability for ground-feeding bird species to cross gaps. Roads in the natural reserves should be designed to be as narrow as possible. In Chapter 3, to investigate the effects of logging on biodiversity, I modeled the recovery of avian communities following a variety of potential logging schemes. I found that, to conserve 80% of the species pool, logging schemes with either cycle length > 40 years or wood volume left after harvest > 55% should be implemented. Wildlife diseases are raising concerns with respect to human and domestic animal health, as well as the persistence of wildlife populations. Chapter 4 was aimed at characterizing the sample prevalence of avian malaria in wild land birds. The prevalence of avian malaria was 45.85%. However, higher parasite prevalence was observed in flocking species compared to solitary species and higher parasite prevalence was observed in adult birds compared to juvenile birds. In Chapter 5, I focused on surveillance for the presence of avian influenza virus nucleic acids and antibodies in wild land birds. Serum samples from four birds out of 197 birds sampled were antibody positive for the H5 subtype. Sample prevalence for avian influenza virus nucleic acids was 7.25%. This result suggests that attention should be given to land birds in AI surveillance and monitoring programs.
Open Access
Bacterial coldwater disease investigations
(Colorado State University. Libraries, 2021) Avila, Brian Walter, author; Winkelman, Dana L., advisor; Huyvaert, Kathryn P., committee member; Fetherman, Eric R., committee member; Hobbs, N. Thompson, committee member
To view the abstract, please see the full text of the document.
Open Access
Bats, elephants, and their food: a conservation perspective on trophic interactions in the Namib Desert
(Colorado State University. Libraries, 2019) Laverty, Theresa Marie, author; Berger, Joel, advisor; Crooks, Kevin, committee member; Wittemyer, George, committee member; Teel, Tara, committee member
To view the abstract, please see the full text of the document.
Open Access
Bayesian analysis of age-at-harvest data with focus on wildlife monitoring programs
(Colorado State University. Libraries, 2007) Conn, Paul Bayne, author; White, Gary C., advisor
State and federal agencies often collect hunter harvest data at check stations. When age- and sex-classes can be determined at the time of harvest, such data provide a wealth of information about population structure. For instance, such summaries are used extensively in quantitative fisheries stock assessment. However, statistically defensible approaches for using age-at-harvest data to monitor terrestrial wildlife populations have not appeared until quite recently, and are deficient in several respects. The primary focus of this dissertation is on developing better methods for analyzing wildlife age-at-harvest data, and on applying these methods to real and hypothetical populations. Chapter one starts by developing statistical methods necessary for fitting population dynamics models to age-at-harvest data. As an example, I analyze marking and harvest records from female black bears (Ursus americanus) in Pennsylvania. In chapter two, I describe numerical implementation issues, as well as results from several extensive rounds of simulation testing. I show that Markov chains will typically need to be quite long to accurately summarize the posterior distribution of model parameters. Nonetheless, estimators are shown to display little bias, to have satisfactory credible interval coverage, and to have a high degree of precision. I show that abundance estimators are quite robust to aging errors, although using data from marked animals twice may lead to overstated measures of precision. In chapter three, I conduct a power analysis to determine if it would be feasible to monitor black bear in Colorado with age-at-harvest and radio telemetry data. My focus in this chapter is on detecting and estimating population trend for varying levels of effort. I show that five year studies are typically too short for all anticipated levels of marking effort, but that ten year studies can yield meaningful estimates of population trend. In chapter four, I address methods that can be used to correct age-at-harvest data for misclassification errors. When the aging criterion is inexact, it is possible to correct for errors if additional information is available on error rates. I illustrate proposed methodology with a black bear dataset from Pennsylvania.
Open Access
Behavior and distribution of American marten (Martes americana) in relation to snow and forest cover on the Kenai Peninsula, Alaska
(Colorado State University. Libraries, 2009) Baltensperger, Andrew Philip, author; Andelt, William F. (William Frank), advisor; Crooks, Kevin R., committee member; Hiemstra, Chris, committee member; Morton, John M., committee member
Marten are sensitive to cold temperatures and normally rely on an insulating snow-pack and sufficient forest structure for thermal protection in winter. Low densities of marten on the western Kenai Peninsula, Alaska have commonly been attributed to shallow snow and habitat conditions that may not be conducive to supporting stable marten populations. This research examined the interactions between marten behavior in relation to available snow and habitat conditions at forest stand, home range, and landscape scales. Marten were radio-collared and back-tracked in three study areas in the Kenai Mountains and Kenai Lowlands to investigate habitat selection and the effects of snow conditions on the movement and resting behavior of marten. An aerial digital videography survey, supplemented by trapping, museum and Kenai National Wildlife Refuge (KENWR) records, was used to generate a minimum landscape distribution estimate of marten on the Kenai Peninsula. Videography detections were overlaid with Geographic Information Systems (GIS) layers for spruce-bark beetle damage and fire history on the Kenai Peninsula. We also tabulated the number of days marten were exposed to conditions in which the subnivean environment was not insulated from below freezing ambient temperatures. Trends in maximum snow depths were calculated by fitting regression lines to historic snow records at Kenai weather stations since 1931.Results demonstrated that marten chose rest sites in structures that would maximize thermodynamic efficiency given the availability of insulating snow cover and warm resting structures. While traveling, marten selected snow and habitat types largely in proportion to their availability at the home-range scale. Movement paths were more tortuous through habitat patches with higher than average canopy densities. Aerial videography surveys detected 32 locations of marten and indicated that the distribution of marten has expanded into the Kenai Lowlands where marten had previously not been reported in any abundance since the beginning of the 20th century. Detections occurred four times as frequently in a large post fire sere burned in 1947 in contrast to an area burned in 1969. Marten were detected in areas extensively damaged by spruce-bark beetles in just six instances and were twice as likely to be located outside of beetle-damaged areas. Average numbers of stress days were inversely related to elevation and the associated differences in snowfall associated with elevation. Analyses of regional maximum yearly snow depths indicated that maximum snow depths have been increasing by 0.29 cm/year in the Kenai Mountains, whereas trends have remained relatively constant in other regions of the Kenai Peninsula. Variations in available snow pack, forest maturity and the availability of resting structures may explain recent shifts in distribution at the landscape level.
Open Access
Behavioral response of mule deer to natural gas development in the Piceance Basin
(Colorado State University. Libraries, 2015) Northrup, Joseph M., author; Wittemyer, George, advisor; Anderson, Charles R., Jr., committee member; Hobbs, N. Thompson, committee member; Hooten, Mevin B., committee member
To view the abstract, please see the full text of the document.
Open Access
Bird and mammal response to large-scale habitat mitigation for game species in the oil and gas fields of northwest Colorado
(Colorado State University. Libraries, 2016) Gallo, H. Travis, author; Pejchar, Liba, advisor; Noon, Barry, committee member; Paschke, Mark, committee member; Wittemyer, George, committee member
To view the abstract, please see the full text of the document.
Open Access
Breeding waterfowl productivity in a flood-irrigated agricultural landscape
(Colorado State University. Libraries, 2023) Setash, Casey M., author; Koons, David N., advisor; Pejchar, Liba, committee member; Gammonley, James H., committee member; Sueltenfuss, Jeremy P., committee member
Similar to agricultural production, the sustainable management of waterfowl populations across the western United States inherently depends on limited water availability. Both endeavors are increasingly challenged by municipal demands for water, drought, and changes in the seasonality of precipitation. Healthy wetlands for wildlife can be sustained in conjunction with the needs of agricultural producers on working lands, but the multifaceted importance of water management is rarely quantified. Information pertaining to the multiple benefits of water management practices might bring to light the larger societal importance of sound water management. This may allow natural resource managers to allocate resources more efficiently and effectively by directing them towards the practices with demonstrated advantages for both wildlife and agricultural producers. The North Platte Basin in north-central Colorado (hereafter North Park) is a model system to evaluate benefits and trade-offs of hydrological manipulations that benefit both agricultural producers and fish and wildlife. Not only are waterfowl and water management already being conducted by federal and state agencies and NGOs like Ducks Unlimited, but North Park is also representative of many working lands throughout the Intermountain West. Agricultural producers in North Park flood irrigate rather than using center-pivot irrigation, which strongly affects on hydrological regimes, water tables, wetlands, and stream flows. Flood irrigation more closely resembles natural stream and river flood regimes and is thought to be more beneficial for wildlife, water table recharge, and evaporative cooling of return flow water. As water resources become diverted for urban municipal uses and the increasing frequency of drought reduces water availability in the semi-arid West, it is believed that the North Platte Basin may begin to play a significant role in the production of waterfowl on a statewide or even a flyway scale. As private land becomes an increasingly important component of waterfowl habitat and water resources become limiting, a strong foundational knowledge regarding how flood-irrigated systems impact wetland-dependent species will therefore be imperative to properly manage waterfowl populations in coordination with agricultural production. We first sought to evaluate the efficacy of flood-irrigated agricultural lands as nesting habitat for breeding waterfowl in the context of land-use intensity. The debate over the best agricultural practices for biological conservation typically focuses on land sharing and land sparing production strategies. One end of the spectrum posits that high-intensity agriculture and the smaller footprint associated with it allows for other land parcels to be spared for biodiversity and therefore provides more suitable habitat, whereas others argue that agricultural lands should be cultivated at a low intensity and interspersed with wildlife habitat, therefore sharing the land with wildlife. We evaluated the demographic consequences of land-sharing and land-sparing practices on breeding bird nest site selection and nest survival, focusing specifically on waterfowl in a flood-irrigated hay agricultural system. We specifically assessed the habitat features related to both shared and spared lands driving nest site selection at two scales and how those same features scaled up to impact nest survival. Nests were located disproportionately closer to uncut irrigated meadows and farther from harvested hay meadows relative to available points, but closer to irrigation ditches. Nests closer to irrigation ditches, uncut irrigated meadows, and open water also experienced higher nest survival. This system is representative of many agricultural systems around the globe and illustrates the ways agricultural practices can shape habitat selection have reproductive consequences for wildlife. After evaluating the importance of wetlands associated with flood irrigation for nesting, we focused our efforts on elucidating their contributions as foraging habitat. Food availability varies considerably over space and time in wetland systems, and consumers must be able to track those changes during energetically-expensive events like breeding. Resource tracking has been studied frequently among herbivores, but rarely receives attention among consumers of macroinvertebrates. We evaluated the change in resource energy density across habitat types and time, and the ability of waterfowl to track macroinvertebrate resources across wetland types and over the course of the breeding season in a high-elevation, flood-irrigated system. We also assessed whether the density of energy resulting from macroinvertebrates explained more of the variation in waterfowl abundance across habitats, or whether the consistency (i.e., temporal evenness) of the resource played a larger role using a pseudo-R2 metric. Energy density varied widely across wetland types, but was highest in basin wetlands (i.e., ponds) and was higher in wetlands with higher temperatures, specific conductivity, and lower dissolved oxygen. Both breeding pair abundance and duckling abundance were positively associated with energy density and resource consistency (R2 = 0.06 for pair abundance and 0.31 for duckling abundance), but energy density explained more of the variation in both waterfowl responses (R2 = 0.77 for pair abundance and 0.58 for duckling abundance). These results have the potential to not only elucidate mechanisms of habitat selection among waterfowl, but also indicate where and when water resources should be allocated as climate conditions become increasingly arid. The technological tools we used initially to evaluate waterfowl use of flood-irrigated habitats (i.e., Global Positioning System [GPS] tags) have become a common tool in ecological studies of animal behavior and demography despite previous research indicating negative impacts on vital rates across a variety of taxa. We therefore focused next on evaluating the impacts of GPS tags on our focal waterfowl species and others across the life-history spectrum. Researchers face tradeoffs when deciding whether they are an appropriate tool because GPS tags may impact vital rates, but they provide detailed data on movements and behavior that often cannot be obtained in other ways. Using band recovery data from hunter harvests, we evaluated the strength of effects induced by GPS tags on annual mortality of adult females across 13 waterfowl species, and whether species with a slower life-history strategy might be more resilient to GPS tag effects than their fast-lived counterparts. Hazard ratios, indicating the risk of death for individuals wearing GPS tags compared to those wearing only metal bands, ranged from 0.92 - 4.38 and the mean difference in survival between marker types across species was 0.31, but these results are averaged across the study period. The magnitude of tag effects remained constant across life-history tempo, indicating that slower-lived species were not able to buffer the effect of wearing GPS tags. When scaling effect sizes up to a currency of fitness, slower-lived species exhibited a similar handicap of wearing GPS tags compared to species with a faster life-history strategy, and the effects were notable. Our results highlight that even small impacts to important vital rates can affect inference pertaining to survival and mortality as well as fitness from birds affixed with GPS tags. The results of this study revealed considerable survival effects across species, although time trends illustrated decreasing effect sizes for most species over time. Results emphasize the importance of testing for such effects in future research as technology advances. Finally, we used components of each previous chapter to characterize the population of breeding ducks in this system and the demographic consequences of environmental conditions. Waterfowl populations in the Intermountain West rely upon water availability and are not as frequently studied as populations within North American core breeding areas like the Prairie Pothole Region. Different species experience different environmental conditions during peak nest initiation depending on their breeding phenology, especially in variable environments like those associated with high-elevation systems. We fit species-specific integrated population models to evaluate the demographic drivers of mallard and gadwall populations breeding in a high-elevation intermountain basin in Colorado representative of many Intermountain West habitats from 2018-2022. Each species initiated nests at opposite ends of the phenological spectrum, allowing us to assess the effects of environmental conditions on demography. Both mallard and gadwall annual after-hatch-year (AHY) female survival probabilities were comparable to estimates from other regions (hatch-year [HY] mallards = 0.48 [SD = 0.09] to 0.53 [SD = 0.07], AHY mallards = 0.53 [SD = 0.07] to 0.57 [SD = 0.05], HY gadwall = 0.44 [SD = 0.13] to 0.52 [SD = 0.14], AHY gadwall = 0.56 [SD = 0.11] to 0. 66 [SD = 0.12]). Annual recruitment, a metric of the number of females produced per breeding pair, was similar among gadwall (0.62 [SD = 0.80] to 1.04 [SD = 1.04]) and mallards (0.40 [SD = 0.48] to 1.59 [SD = 0.95]), but realized population growth rate (λ) did not vary as much for gadwall (0.93 [SD = 0.56] to 1.21 [SD = 0.59]) as it did for mallards (0.76 [SD = 0.24] to 1.55 [SD = 0.24]). Recruitment of both species exhibited quadratic relationships with spring growing degree days, indicating recruitment was higher during springs with intermediate temperatures, and spring snow-water equivalent metrics in the surrounding mountains positively impacted HY and AHY mallard survival in addition to HY gadwall survival. The results of this study emphasize the need for continued monitoring of waterfowl outside of traditional survey areas and provide insight into water management strategies to target important vital rates as climate and land use change.
Open Access
Calcium, telomere length, and parasitism in passerines nesting at high elevation
(Colorado State University. Libraries, 2020) Rodriguez, Marina D., author; Huyvaert, Kathryn P., advisor; Doherty, Paul F., Jr., advisor; Bailey, Susan M., committee member
Most organisms are exposed to numerous environmental stressors at various points throughout life, and, through natural selection, organisms' responses to such stressors have been optimized by natural selection for the best fitness outcomes. During the breeding season, wild vertebrates often make a trade-off between current reproduction and self-maintenance when dealing with environmental stressors. The total cost of reproduction is made up of all of the resources and energy that go into activities related to reproduction (e.g., nest building, finding a mate, foraging for food and nutrients related to offspring production, parental care) that do not go into self-maintenance. The cost of these activities can vary depending on resource availability, where limited resources can increase the cost associated with breeding due to increased energy associated with foraging and competing for the resource. In birds, calcium is a critical resource due to its importance in egg production and offspring development, and low calcium availability often leads to decreased reproductive success. In my first chapter, I used an experimental approach to assess the effects of supplemental calcium on reproductive parameters of Tree Swallows (Tachycineta bicolor) in a high elevation environment. Calcium-supplemented birds in my study area laid more, larger eggs, and had higher hatching success compared to control females. These results provide evidence that calcium availability is a constraint on breeding Tree Swallows at high elevation, perhaps due to the harsh conditions and concomitantly higher metabolic costs that force a costlier and more intense trade-off between foraging for food or for calcium. The increase in reproductive parameters for calcium supplemented nests in Chapter 1 highlights a cost associated with calcium foraging that constrains reproduction. For my second chapter, I aimed to better understand how calcium availability affects the cost of reproduction in mother Tree Swallows and offspring by using telomere shortening as a proxy of life stress and lifespan. Telomeres are terminal features of chromosomes consisting of repetitive DNA sequences that shorten with age and stress, and whose length is positively correlated with survival. I used telomere shortening as a proxy for the costs associated with reproduction to better understand life history trade-offs of Tree Swallows at high elevation sites. Similar to Chapter 1, I found that Tree Swallows supplemented with calcium had higher reproductive success, although I also found that supplemented nests had more telomere shortening compared to birds at control nests. These results provide evidence that Tree Swallows supplemented with calcium experience higher reproductive output at the cost of lower expected survival in the form of more telomere shortening. While investing resources in reproduction may lead to higher reproductive output for the current breeding season, this increase in reproductive success can come with a cost to survivorship. One way that resource allocation can shape survivorship is through investment in immune function. In many systems, however, more species-level and individual-level research is needed on host-parasite relationships before trade-offs between immune function and reproduction can be assessed. For my third chapter, I conducted a survey of avian Haemosporida: blood parasites that include those that cause avian malaria. I surveyed an avian community for haemosporidian parasites in the Colorado Rocky Mountains in order to estimate prevalence and diversity of blood parasites and to find species-level and individual-level characteristics that influence infection prevalence. I found that open cup nesters have higher blood parasite prevalence than cavity or open cup nesters. Additionally, male Ruby-crowned Kinglets, White-crowned Sparrows, and Wilson's Warblers had a higher prevalence of haemosporidian parasites compared to the other species analyzed, as did Red-breasted Nuthatches, which, like Ruby-crowned Kinglets, have a high body condition index. This chapter presents baseline knowledge of avian blood parasite presence, prevalence, and diversity across avian species in the Colorado Rocky Mountains and adds to our knowledge of host-parasite relationships of blood parasites and their avian hosts.
Open Access
Can copper-based substrates be used to protect hatcheries from invasion by the New Zealand mudsnail?
(Colorado State University. Libraries, 2011) Hoyer, Scott, author; Myrick, Christopher A., advisor; Clements, William H. (William Henry), 1954-, committee member; Kondratieff, B. C. (Boris C.), committee member
Aquaculture facilities throughout North America are at risk of invasion by the New Zealand mudsnail (Potamopyrgus antipodarum). Mudsnails can enter facilities in several ways including by crawling through effluent pipes. There is evidence to suggest that lining the insides of these pipes with copper-based substrates to create a contact deterrent could reduce the risk of mudsnail invasion. However, before copper-based deterrents can be recommended for wide-scale use, it is important that we understand how these materials perform across the range of physicochemical conditions common to hatcheries. The goal of this project was to evaluate the relative ability of four types of copper-based materials (copper sheet; SC (0.323 mm, 99.9% pure), copper mesh; MC (6.3 opening/cm, 99% pure), copper-based ablative anti-fouling paint; AP (Vivid Anti-fouling Paint, 25% cuprous thiocyanate as the active ingredient), and copper-based non-ablative anti-fouling paint; NP (Sealife 1000, 39% cuprous oxide as the active ingredient)) to serve as effective mudsnail contact deterrents across a range of water temperatures (8, 12, 18, and 24° C), hardness (75, 125, 175, and 300 mg/L as CaCO3), pH (6, 7, and 8.5), fouling (0, 6, and 10 weeks of exposure), and water velocities (0, 9, and 33 cm/s). Each of these factors was evaluated in a sequential set of separate experiments conducted at the Colorado State University Foothills Fisheries Laboratory during 2009-10. Mean crawling distance (MCD) of the mudsnails in the temperature, hardness, and pH experiments was significantly lower on the SC and MC surface treatment compared to the NP treatment (p < 0.05). Additionally, maximum observed crawling distance (CDmax) was also consistently lower on the SC (1139 mm), MC (672 mm), and AP (1509 mm) treatments versus the NP (1969 mm) treatment. The NP treatment was the only surface where MCD was significantly affected by all three physicochemical parameters (p > 0.05). In the fouling experiment, MCD increased significantly on the AP surface treatment after exposure to fouling from 353 ± 83 mm (mean ± SE) at week 0 to 1207 ± 196 at week 6; no significant increase in this parameter was found on either solid copper surface. Finally, in the water velocity experiment, overall MCD on the copper surfaces was significantly lower in the 0 cm/s velocity treatment (30 ± 6.3 mm) compared to either 9 cm/s (302 ± 47.4 mm) or 33 cm/s (278 ± 50.2 mm). Under flowing water conditions, MC was the most effective treatment for limiting the MCD and CDmax of the mudsnails. Finally, there was no evidence to suggest that at the levels tested, velocity alone could serve as a deterrent to mudsnails. Overall, MC and SC were the most effective surfaces in terms of limiting the locomotor activity of the mudsnail. We recommend that barriers constructed of either of these materials be a minimum of 250 cm to provide a satisfactory level of protection against mudsnail invasion. Additional considerations including design and integration with other types of barriers are discussed.
Open Access
Cinnamon teal breeding ecology in the San Luis Valley of Colorado
(Colorado State University. Libraries, 2018) Setash, Casey M., author; Kendall, William L., advisor; Doherty, Paul F, Jr.., committee member; Aldridge, Cameron L., committee member; Olson, David, committee member
The foundation of effective waterfowl management is an abundant and resilient waterfowl population, which begins with an understanding of what drives population size and growth. Population growth rate is the product of a number of vital rates, all of which remain relatively unknown for the cinnamon teal (Spatula cyanoptera). I investigated the interactions between biotic and abiotic factors influencing the basic demographic rates of cinnamon teal during the breeding season in the San Luis Valley of Colorado. Specifically, I assessed the relationship between the habitat around a selected nest site and cinnamon teal nesting success. Additionally, I evaluated whether a relatively novel approach to surveying social groupings of waterfowl can act as an effective index of breeding effort and success for cinnamon teal, the intraspecific variation in nest attendance patterns during incubation and how it affects nest survival, and the rates at which breeding females and ducklings survive the breeding season. This research has the potential to enhance the understanding of the basic population ecology of this overlooked species and provide information about vital rates that can be used in future analyses and management of the population on a larger scale. I found that cinnamon teal select nest sites with habitat characteristics that are also associated with a higher probability of nest survival (Chapter 2, this thesis). Specifically, I observed cinnamon teal selecting nest sites characterized by a lower proportion of forbs relative to what was available, which were also associated with higher nest survival among the nests I observed. I established that weekly transect surveys assessing the social groupings of cinnamon teal throughout the breeding season have the potential to act as an index of reproductive success if done on a larger scale (both temporally and geographically; Chapter 3, this thesis). I also found differences in the nest attendance patterns during early incubation compared to late incubation, which were also impacted by time of day and temperature (Chapter 4, this thesis). Finally, I estimated breeding season duckling and hen survival rates that were comparable to other waterfowl species and provided suggestions for future cinnamon teal researchers (Chapter 5, this thesis).
Open Access
Cold summer stream temperatures reduce recruitment of native cutthroat trout populations
(Colorado State University. Libraries, 2007) Coleman, Mark Anthony, author; Fausch, Kurt D., advisor
Translocation is a key strategy for conserving subspecies of native cutthroat trout Oncorhynchus clarkii, which have declined markedly throughout their native ranges in North America. Previous research showed that translocation success in high-elevation southern Rocky Mountain streams was more likely in warmer streams, and suggested that cold temperatures could limit juvenile trout recruitment and explain translocation failures. However, the effects of cold temperature on recruitment had not been previously investigated. I studied these effects using an integrated laboratory and field approach. In the lab, age-0 Colorado River cutthroat trout O. c. pleuriticus were subjected to one of three natural temperature regimes during two years, which averaged 7°C, 8.5°C and 10.0°C during the warmest summer month. From hatching to swimup, mean survival was high during both years, ranging from 97% (warm regime) to 85% (cold). After swimup, warm regime fry had much greater survival and grew more than 60% larger, on average, than cold regime fry by the onset of winter in the 2003 experiment. The pattern of lower survival in colder temperature regimes held through mid-winter, with 76% survival (warm regime), 62% (intermediate), and 29% (cold). Likewise, during the 2004 experiment, survival to early winter ranged from 44% (warm regime) to 10% (cold). Most mortality in all treatments occurred during a recruitment bottleneck encompassing a 4- to 6-week period following swimup. A response surface analysis of percent dry weight data indicated that the energy content of fry at swimup was lower in colder regimes, and declined during the recruitment bottleneck in all regimes. In the field, I monitored temperatures and conducted surveys to estimate densities of age-0 fry at peak emergence in six headwater streams that varied in thermal characteristics. Density and growth increased with Celsius degree days during the growing season. My results indicate a strong recruitment bottleneck after swimup, when temperature-related energy deficits probably cause significant mortality. Fisheries managers in the southern Rocky Mountains may increase translocation success of native cutthroat trout by selecting sites with ≥800-900 degree days during the growing season, and fry grow to ≥30-35 mm by the end of the growing season.
Open Access
Comparative winter nutrition of elk in the Jemez Mountains, New Mexico
(Colorado State University. Libraries, 1981) Rowland, Mary M., author; Alldrege, A. William, advisor; White, Gary C., committee member; Bailey, J. A., committee member
Diet quality and nutritional status of elk {Cervus elaphus nelsoni) were studied in the Jemez Mountains, New Mexico, during January-April 1980. A recently burned montane area, including portions of Bandelier National Monument, and an unburned upper montane area in the Valle San Antonio were selected for winter range comparisons. Botanical composition of elk diets, determined by microhistological analysis of feces, was markedly different between the 2 areas, passes dominated diets in the burned area (x =90%), but were consumed in nearly equal proportions with browse in the unburned area (x = 52%, grasses; x = 41%, browse). Forbs were minor dietary components in both areas. Diet botanical com-position did not vary during the winter and early spring. Grasses were more digestible than was browse, but crude protein content was similar between forage classes. Temporal increases in quality of grasses were significant, whereas browse forages remained relatively constant in quality. Comparisons of forage protein and IVDOM (in vitro digestible organic matter) revealed no differences between locations. Dietary protein ranged from 3.5-7.2% in Bandelier and from 4.7-7.5% in the Valle San Antonio, and was consistently superior in the unburned area. Increases in diet IVDOM in Bandelier (35% to 48%) surpassed those in the Valle San Antonio (33% to 39%) and were more rapid in Bandelier. Increases in diet quality were highly correlated with changes in quality of grasses consumed by elk. Observed disparities in diet quality between areas were caused primarily by differences in diet compositions and the differing qualities of grasses vs. browse. Forage quality was more variable than was diet quality, indicating the ability of elk to maintain relatively constant diet quality when confronted with large fluctuations in forage quality. A simulation model of ruminant energy and nitrogen balance was used to predict potential effects of diet quality on elk nutritional status. Greater energy deficits were predicted for elk in the unburned area, effecting greater losses of fat and lean body. Superior dietary nitrogen in the unburned area was insufficient to compensate for these losses.
Open Access
Demographic consequences of agricultural practices on a long-lived avian predator
(Colorado State University. Libraries, 2022) Vennum, Christopher Ryan, author; Koons, David N., advisor; Pejchar, Liba, committee member; Kendall, Bill, committee member; Boone, Randall, committee member
To view the abstract, please see the full text of the document.
Open Access
Density, demography, and seasonal movement of snowshoe hares in central Colorado
(Colorado State University. Libraries, 2011) Ivan, Jacob Scott, author; White, Gary C., advisor; Shenk, Tanya M., committee member; Wilson, Kenneth R., committee member; Doherty, Paul F., committee member; Romme, William H., committee member
To view the abstract, please see the full text of the document.