Theses and Dissertations at Montana State University (MSU)
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Item Reproductive and juvenile ecology of mountain whitefish in the upper Green River, Wyoming(Montana State University - Bozeman, College of Letters & Science, 2022) Brown, Colter Davis; Chairperson, Graduate Committee: Christopher S. GuyMountain Whitefish Prosopium williamsoni are a salmonid native to the northern Rocky Mountains that has experienced declines in population abundance in rivers throughout Idaho, Colorado, Wyoming, and Montana. Problems with recruitment are suspected, but often the specific mechanisms causing population declines are unknown. Our approach to better understand the mechanisms that influence Mountain Whitefish population dynamics was to compare population characteristics between the Green River, Wyoming and the Madison River, Montana populations. Boyer et al. (2017a) conducted an extensive study on the movement and reproductive ecology of Mountain Whitefish in the Madison River, and we used this study as a template to make direct comparisons between the populations. Our primary research questions were 1) what is the age and length at first maturity, spawning periodicity, fecundity, and age structure of Mountain Whitefish, 2) what is the spatial and temporal distribution of Mountain Whitefish through their spawning period, and what influence do abiotic factors have on spawning and movement, and 3) what is the spatial distribution and habitat use of age-0 Mountain Whitefish? We collected otoliths and gonadal samples from 127 Mountain Whitefish in the Green River, implanted 100 fish with radio transmitters and tracked them from September 1 to early November in 2019 and 2020, determined spawning period and locations using egg mats, kick netting, and angling, and sampled age-0 Mountain Whitefish using a beach seine in slow-water habitats. The geographic separation and difference in hydrogeomorphic conditions between the systems allowed us to form generalizations about Mountain Whitefish in the Intermountain West. We found Mountain Whitefish in both systems mature between ages 2 and 4, primarily spawn annually, have a similar relative fecundity, spawning movements vary, males begin movement prior to females, and age-0 fish drift downstream of spawning locations and use slow-water silt-laden habitats after hatching. The main disparities between systems were that in the Green River water temperature was more suitable for embryo development, and age structure was more uniform and older. This research enhanced our understanding of Mountain Whitefish reproductive and juvenile ecology and provided evidence for factors that may influence recruitment of Mountain Whitefish.Item Retrospective analysis of a declining trumpeter swan (Cygnus buccinator) population in Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2021) Shields, Evan Michael; Chairperson, Graduate Committee: Jay J. RotellaBy 1933, the number of trumpeter swans (Cygnus buccinator) in the continental United States was reduced to roughly 70 individuals that nested and wintered in Yellowstone National Park (YNP) and the surrounding Greater Yellowstone area. While conservation measures saved the trumpeter swan, and their numbers have increased greatly across North America, abundance and productivity of YNP's resident trumpeter swan population declined from the 1960's through about 2010. Many hypotheses for the initial decline in YNP trumpeter swans exist, including human disturbance at nesting areas, changes in habitat quality, predation, and management of trumpeter swans outside of YNP. To improve knowledge and take advantage of long-term monitoring of trumpeter swans, this retrospective study was designed to evaluate the various competing hypotheses about possible factors associated with temporal and spatial variation in swan abundance and reproductive success in YNP for 1931-2019. Two different types of analyses were used: (1) analysis of annual park-wide counts of trumpeter swan territories with swans Absent, Present but unsuccessful (Present), and Successful, and (2) Bayesian reversible jump Markov chain Monte Carlo analysis that evaluated the utility of covariates representing swan decline hypotheses for explaining variation in annual, territory-level patterns of where swans were Absent, Present, and Successful each year. My results provide novel information on temporal patterns in the annual number of Absent, Present, and Successful territories, and analysis of covariates that are useful to explain variation in territory statuses identified several interesting covariate relationships. Swan territories within YNP were more likely to have trumpeter swans Present as opposed to Absent during 1931-2011 in years when total abundance of trumpeter swans in the broader geographic area around YNP was greater. Because several covariates have values that trend through time, it is difficult to distinguish between several alternative interpretations for the underlying causes of temporal trends. Identification of swan territories most likely to have swans Present and Successful can be a useful tool to help YNP staff manage important swan habitat or justify targeted management actions. Future work that utilizes satellite imagery to reconstruct lake/wetland hydrology is likely to be useful to describe potential changes in habitat quality.Item Combination of acoustic telemetry and side-scan sonar provides insight for lake trout Salvelinus namaycush suppression in a submontane lake(Montana State University - Bozeman, College of Letters & Science, 2021) Siemiantkowski, Michael James; Chairperson, Graduate Committee: Christopher S. GuyExpansion of an invasive Lake Trout Salvelinus namaycush population in Swan Lake, Montana threatens a core area population of Bull Trout Salvelinus confluentus in Montana. Given the increased efficacy of suppression using novel embryo suppression methods, there is renewed interest in Lake Trout suppression in Swan Lake. The specific questions of this study were: 1) where are Lake Trout spawning, 2) where are the most used spawning sites, 3) what is the amount of spawning habitat, 4) does the estimated spawning area differ between estimates from telemetry locations and side-scan sonar imagery of suitable spawning substrate, and 5) how much phosphorous and nitrogen would be added to Swan Lake if carcass-analog pellet treatments were implemented? Acoustic tags were implanted in 85 Lake Trout in July and August of 2018 and 2019. Nightly tracking efforts during September, October, and November of 2018 and 2019 resulted in 1,744 relocations for 49 individual Lake Trout. Kernel-density analysis was used to evaluate Lake Trout aggregation locations identifying 10 distinct spawning sites -- corroborating previous studies. Visual observation of Lake Trout embryos confirmed spawning at three sites with the remaining seven sites considered to be unconfirmed spawning sites. All confirmed spawning sites were located in the littoral zone along areas of steep bathymetric relief and were the most used across both spawning seasons. In 2019, side-scan sonar imaging was used to classify and quantify the total area of suitable spawning substrate, which comprised 12.8% of the total surface area estimated for confirmed sites and 11.4% for unconfirmed spawning sites. Simultaneous treatment of all confirmed and unconfirmed spawning sites would require 205,709 + or - 86 kg of carcass-analog pellet material, resulting in 370.4 + or - 0.2 kg of phosphorous and 7,487.9 + or - 3.1 kg of nitrogen inputs to Swan Lake. Thus, pellet treatment would increase the Carlson's trophic state index (TSI) values from 20.8 to 27.7 for total phosphorous, and from 22.1 to 26.2 for total nitrogen. Based on a TSI threshold value of < 40 for an oligotrophic lake, the use of carcass-analog pellets could be a feasible addition to renewed Lake Trout suppression efforts in Swan Lake.Item Fish assemblage response to habitat restoration in Elk Springs Creek, Montana: implications for arctic grayling (Thymallus arcticus) restoration(Montana State University - Bozeman, College of Letters & Science, 2021) Marsh, Jason William; Chairperson, Graduate Committee: Alexander V. ZaleThe abundance and distribution of Arctic Grayling Thymallus arcticus in Montana have declined substantially during the past century as a result of habitat degradation and loss. Biologists tasked with conserving Arctic Grayling populations in the Centennial Valley of southwestern Montana implemented two habitat restoration projects to reclaim historical Arctic Grayling migration corridors and spawning habitats in Elk Springs Creek. I used before-after and before-after control-impact (BACI) study designs to evaluate the effects of these habitat restoration projects on physical habitat, water quality, and Arctic Grayling in Elk Springs and Picnic creeks. Because Arctic Grayling were rare in Elk Springs and Picnic creeks, I also examined the effects of restoration on two additional species (Brook Trout Salvelinus fontinalis and White Suckers Catostomus commersonii) with habitat requirements and life history characteristics similar to those of Arctic Grayling. I used electrofishing to monitor the abundance, biomass, and size distribution of each species before the restoration in 2016, and after the restoration during 2017 and 2018. A PIT-tag detection network monitored the seasonal movements of Arctic Grayling, Brook Trout, and White Suckers from spring 2016 through autumn 2018. In situ data loggers measured summer stream temperatures and dissolved oxygen concentration in expected fish migration corridors both before and after restoration. The abundances and biomasses of Arctic Grayling and White Suckers were similar before and after restoration. However, Brook Trout abundance and biomass increased significantly in the restored (impacted) reaches relative to the unrestored (control) reaches two years after habitat restoration. The size-class distributions of Arctic Grayling and Brook Trout broadened after restoration. Movements of Arctic Grayling, Brook Trout, and White Suckers among unique habitat segments in Elk Springs and Picnic creeks increased after restoration, but pre-restoration movement data was sparse and limited inference. Following channel restoration, summer stream temperatures decreased, and dissolved oxygen concentration increased and equilibrated. Physical habitat improved (i.e., fine sediments decreased, and depth, percentage of pools, and gravels increased) in restored historical Arctic Grayling spawning areas. I thereby showed that channel reconnection and spawning habitat restoration can substantially improve water quality and physical habitat. However, the restoration measures implemented in Elk Springs Creek affected my target species disproportionately.Item Is habitat constraining bighorn sheep distribution and restoration: a case study in the Greater Yellowstone Ecosystem(Montana State University - Bozeman, College of Letters & Science, 2019) Lula, Ethan Shawn; Chairperson, Graduate Committee: Robert A. GarrottRocky Mountain Bighorn Sheep (Ovis canadensis) restoration continues to be a challenge throughout western North America despite nearly a century of efforts dedicated to the species' recovery. A persistent problem for restoration is populations failing to expand into surrounding areas of habitat even during years of population growth. While populations can be constrained by several environmental factors and behavioral tendencies, we contend habitat availability is not the primary limiting factor. This study incorporated GPS data from bighorn sheep within the Taylor-Hilgard population in the Madison Mountain Range, located in the northwestern extent of the Greater Yellowstone Ecosystem (GYE), to develop summer and winter resource selection function (RSF) habitat models. The objective of this study was to evaluate a hypothesis that habitat was not the primary factor limiting distributions of bighorn sheep within the Madison Range by developing biologically-plausible RSF models and using covariates expected to influence selection. Multiple functional forms and spatial grains for covariates were considered and sets of summer and winter resource selection models compared using AIC subscript c. Results indicated that bighorn sheep resource selection was grain dependent, with bighorn sheep generally selecting covariates at the larger 500 m and 1,000 m spatial grains. Summer selection was characterized by rugged terrain, steep slopes, reduced canopy cover, southwestern aspects and ridgelines. Winter selection was characterized by low elevations, southwestern aspects, steep slopes, reduced canopy cover, ridgelines, high summer NDVI amplitude, and areas close to steep terrain (slopes > or = 45°). Predicted winter habitat occurred in a non-contiguous distribution primarily along low-elevation, southwest-facing aspects within the Madison Valley, and predicted summer habitat was concentrated along high elevation ridgelines. Model results were successfully validated using independent GPS data. Potential abundance for the Madison Range was estimated by linking the winter RSF to population estimates for the Taylor Hilgard and results suggested that the Range may be capable of supporting 2 to 4 times the number of bighorn sheep currently estimated. Study results supported the hypothesis that habitat was not the primary factor limiting extant bighorn sheep populations, suggesting that broader distributions within the Range are possible if novel restoration strategies are considered.Item Recent and historical water use strategies of western U.S. conifers(Montana State University - Bozeman, College of Letters & Science, 2017) Clute, Timothy; Chairperson, Graduate Committee: David Roberts; Jia Hu (co-chair); Jia Hu was a co-author of the article, 'Investigating the variation in inter- and intraspecific physiological plant hydraulic traits across an elevation gradient' which is contained within this thesis.; Jia Hu was a co-author of the article, 'Historic influence of climate on conifer water status in northwestern Montana' which is contained within this thesis.Understanding the physiological traits that trees utilize to manage water use can reveal important insights into how and why they occur in their realized habitat. Among the tools to investigate these traits include measuring trees' seasonal water status, deciphering trees' rooting depth, and measuring the trees' vulnerability to cavitation. However, it is equally important to understand how complex landscape heterogeneity will affect both the inter- and intraspecific variation of these physiological traits. This thesis seeks to quantify the variation of the physiological traits used to manage water status among three common Rocky Mountain conifers; Pseudotsuga menziesii (a plastic species occurring across xeric and mesic sites), Pinus ponderosa (a xeric species), and Picea engelmannii (a mesic species), occurring across an elevation gradient. Furthermore, it aims to link tree maintenance of water status to source water, and understand how the importance of source water is reflected in the tree ring record. In the first chapter, I sought to quantify inter- and intraspecific variation of these three species by measuring diurnal and seasonal water status, seasonal water use, and xylem vulnerability to cavitation at a low elevation xeric site, composed of P. ponderosa and P. menziesii, and a high elevation mesic site, composed of P. engelmannii and P. menziesii. We found good evidence for interspecific variation in the physiological traits to manage water status at both sites. However, we did not find strong evidence for intraspecific variation in these same traits within our plastic species (P. menziesii). In the second chapter, we investigated how stable isotopes in tree rings reflected seasonal source water use as well as the atmospheric conditions the trees were growing under. At the low elevation site, we found evidence that the tree ring isotopes were likely reflecting both seasonal precipitation inputs as well as the atmospheric growing conditions. At the high elevation site, trees likely only reflected the atmospheric growing conditions and did not reflect seasonal water use.Item Understanding the effects of wildfire on the functional traits of plants and bees(Montana State University - Bozeman, College of Letters & Science, 2018) Durney, Janice Simone; Chairperson, Graduate Committee: Laura BurkleDiversity, often assessed by species richness, fosters ecosystem success, promoting ecosystem services, stability, and adaptation. Evaluations of functional trait composition are a better indicator of ecological process dynamics. Functional trait variation of species within a community (i.e., inter-specific variation) and of individuals within a species (i.e., intra-specific variation) may reflect adaptations and phenotypic variation contributing to the functional diversity of a community in the face of change. Wildfires have shifted from mixed-severity to frequent high-severity fires, due to fire suppression and climate change, modifying ecosystem function, trait selection pressure, and species sorting. Traits involved in plant-pollinator interactions can be used to understand the mechanisms underlying shifting interactions across communities and how post-wildfire environmental conditions affect community assembly, structure, and stability. We tested how productivity, time-since-burn, and wildfire severity influenced mean functional trait values and inter- and intra-specific functional trait variation of plants and bees known to interact in southwestern Montana, USA. Fieldwork was conducted from 2013-2017 in two locations that differed in productivity with similar fire histories of recent-mixed-severity, recent-high-severity, older-high-severity burns, and unburned areas. Functional traits involved in plant-bee interactions were selected and measured among plant and bee species observed across these various productivity, time-since-burn, and fire severity levels. We found that as productivity and time-since-burn increased, the mean functional trait values and inter- and intra-specific functional trait variation of plants and bees increased. In addition, productivity, time-since-burn, and fire severity affected the functional trait values and variation of plant species more than bee species. These results suggest that as productivity and time-since-burn increases so does trait diversity - promoting ecosystem function and stability. The increased effect of productivity and time-since-burn on plant functional traits compared to bee traits suggests the dispersal abilities of bees allow them to cope with the effects of fire, while plant species are more prone to productivity and time-since-burn habitat filtering and species sorting, potentially due to limited mobility. Our results support previous findings that shifting wildfire regimes from mixed to high-severity burns increases species sorting and limits trait variation after wildfire regardless of productivity but trait variation increases as time-since-burn and productivity increases.Item The influence of sampling design on the characterization of in-stream salmonid habitat(Montana State University - Bozeman, College of Letters & Science, 2019) Clark, Christopher Lee; Chairperson, Graduate Committee: Thomas E. McMahon; Robert Al-Chokhachy (co-chair); Robert Al-Chokhachy, George Pess and Thomas McMahon were co-authors of the article, 'Using continuous surveys to evaluate precision and bias of habitat inferences from different reach-scale sampling alternatives' submitted to the journal 'Canadian journal of fisheries and aquatic sciences' which is contained within this thesis.Pacific salmon have endured widespread population extirpations with some estimates at nearly one third of historical populations. In the western coterminous United States Pacific salmon no longer inhabit upwards of 40% of their historical freshwater range. Reintroducing Pacific salmon has therefore become a common conservation effort. An early step in evaluating potential reintroductions includes quantifying the available habitat, however the quantification, and interpretation of the habitat can be influenced by the sampling design and methods chosen. Reach-based sampling designs have been used extensively to collect fisheries related data; however, few studies have examined how reach-based inferences may be biased, a particular concern given the non-random distribution of factors such as woody debris and the magnitude of site-to-site variability. To address this concern, I collected reach-based habitat data continuously within streams. I then used simulations to resample the streams which were delineated into discrete reaches. During simulations I applied simple random, simple random with unequal probability, and generalized random tessellation stratified sampling designs and chose three habitat attributes that are commonly collected in stream habitat surveys, thought to be important factors for Pacific salmon survival, and expected to be distributed differently across the riverscape. My goal of identifying potential bias and precision under these sampling designs was achieved by summarizing simulations and comparing simulated results across streams, attributes, sampling designs and ultimately the census derived estimate of an attribute. My results indicate the extent of bias and levels of precision varied not only across habitat metrics but also across streams. My analyses suggest the use of reach-based approaches, particularly with low sampling efforts, can result in substantially different estimates of habitat characteristics and erroneous estimates of habitat carrying capacity of fishes.Item Impacts of weather, habitat, and reproduction on the survival and productivity of wild turkeys in the northern Black Hills, South Dakota(Montana State University - Bozeman, College of Letters & Science, 2019) Yarnall, Michael James; Chairperson, Graduate Committee: Andrea Litt; Andrea R. Litt, Chad P. Lehman and Jay J. Rotella were co-authors of the article, 'Precipitation and reproductive effort combine to alter survival of wild turkey hens in the northern Black Hills, SD' submitted to the journal 'Journal of wildlife management' which is contained within this thesis.; Andrea R. Litt, Chad P. Lehman and Jay J. Rotella were co-authors of the article, 'Impacts of weather on reproductive productivity of wild turkeys in the northern Black Hills, SD' submitted to the journal 'Journal of wildlife management' which is contained within this thesis.The study of population ecology is motivated by a desire to understand variation in the factors that drive wildlife population dynamics. Robust vital rate estimates are crucial for effective wildlife conservation and management, particularly for at-risk or harvested species. In avian populations, the survival of females, nests, and young are important drivers of population growth, although the relative importance of each rate can differ among species. Annual and regional variation in vital rates within species is common; further, local climatic and habitat conditions may influence population dynamics. During 2016 - 2018, we used radio telemetry to study the impacts of weather and habitat conditions on the survival and productivity of Merriam's wild turkeys (Meleagris gallopavo merriami) in the northern Black Hills of South Dakota. Specifically, we quantified the impacts of 1) precipitation and reproductive effort on hen survival, 2) precipitation and habitat conditions on nest survival, and 3) precipitation and temperature on early poult survival. Precipitation reduced the survival of hens and nests, although the magnitude depended on the hen's incubation status or the vegetation characteristics at the nest site. Based on precipitation data from 2017, the estimated annual survival rate for a hen that did not incubate was 0.535 (SE = 0.038), whereas that and for a hen that incubated for 26 days was 0.436 (SE = 0.054). The probability that a nest would survive from initiation to hatching for a nest initiated by an adult hen on the median date of nest incubation in 2017 was estimated to be 0.432 (SE = 0.084). The estimated probability that a poult would survive from hatching to 4 weeks of age was 0.387 (SE = 0.061). Our results clearly demonstrate a negative cost of reproduction, as predicted by life-history theory, and show that hens and nests in this ecosystem are more vulnerable to predation during or immediately following rainfall, as predicted by the moisture-facilitated nest-predation hypothesis. Survival and productivity of turkeys was lower in our study area than in other portions of the Black Hills; we recommend that managers take steps to limit human-induced hen mortality of this important game species.Item Effects of seasonal precipitation and habitat associations on the demographics of Mexican spotted owl prey in the canyonlands region of southern Utah(Montana State University - Bozeman, College of Letters & Science, 2018) Thornburg, John Ramsey, III; Chairperson, Graduate Committee: David WilleyMost food habit studies of Mexican Spotted Owls (Strix occidentalis lucida) have been conducted in forested environments in more southern portions of their range. Through regurgitated pellet analyses, these studies showed the majority of Mexican Spotted Owl prey consumed was comprised of Cricetid rodents, specifically woodrats (Neotoma spp.) and white-footed mice (Peromyscus spp.). In the northernmost portions of their range, Mexican Spotted Owls inhabit rocky canyon habitats within the Colorado Plateau. In the canyonlands region, few studies have investigated the population ecology and habitat associations of the primary prey of spotted owls and no studies have examined the relationships among primary prey demographics and their responses to seasonal precipitation. Given the Mexican Spotted Owls status as a threatened species, increased knowledge of prey species relationships with climate and habitat may assist in future management of spotted owl populations across the canyonlands region. Using a seven-year historic data set collected at three study sites in Grand Staircase -- Escalante National Monument from 2001 to 2007 and three years of data collected at five study sites in Capitol Reef National Park from 2013 to 2015, I described the nocturnal small mammal communities, investigated primary prey habitat and microhabitat component associations, and investigated the effects of timing and amount of seasonal precipitation on primary prey abundance and diversity in both study areas. Cricetid rodents were the most abundant nocturnal small mammals and potential prey available for spotted owls inhabiting rocky canyon habitats. Microhabitat analyses revealed Cricetid rodents partitioned space and resources that minimized interspecific competition enabling coexistence in narrow canyon systems with limited biological resources. Linear mixed-effects modeling indicated winter precipitation was the primary driver of spotted owl primary prey demographics in the canyonlands region.