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Item Mechanisms of rainbow trout hybridization with native cutthroat trout in the Lamar River of Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2019) Heim, Kurt Conrad; Chairperson, Graduate Committee: Thomas E. McMahon; Thomas E. McMahon, Clint C. Muhlfeld, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Interspecific hybridization solves a phenological breeding mismatch for a nonnative invader' submitted to the journal 'Ecology' which is contained within this dissertation.; Thomas E. McMahon, Steven T. Kalinowski, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Invasive hybridization in a high-elevation stronghold: genetic status of Yellowstone cutthroat trout in the Lamar River of Yellowstone National Park' submitted to the journal 'Canadian journal of fisheries and aquatic sciences' which is contained within this dissertation.; Thomas E. McMahon, Brian D. Ertel and Todd M. Koel were co-authors of the article, 'Leveraging public harvest for genetic management: identification and exploitation of invasive hybrid trout in Yellowstone National Park' submitted to the journal 'Biological invasions' which is contained within this dissertation.Invasive hybridization--when invasive species interbreed with native species--is a pervasive conservation issue. Hybridization presents difficult management decisions and poses complex problems at the intersection of contemporary evolution, invasion biology, physiology, and landscape ecology. I examined the invasion scenario playing out in the Lamar River watershed of Yellowstone National Park where native Yellowstone cutthroat trout (YCT) are undergoing hybridization with introduced rainbow trout (RT). I first test the hypothesis that a breeding timing mismatch of an invasive species (i.e., RT often spawn far earlier than YCT, and eggs are scoured by snowmelt runoff) can be overcome by hybridization with a locally adapted native species, that spawn later (Chapter 2). I found support for this hypothesis. Spawning timing was strongly related to the degree of non-native admixture at the individual level, indicating that hybridization alters breeding timing in ways that could benefit hybrids. At the population level, hybrid spawning timing closely matched that of native taxa and was strongly correlated to stream flow conditions. Overall, these data suggest poorly matched spawning timing is unlikely to serve as a strong mechanism limiting invasive hybridization of YCT. Next, I mapped the spatial distribution of hybridization in the Lamar River watershed (Chapter 3). Many non-hybridized populations persist in the upper watershed, whereas a prominent source of RT in the lower watershed has likely contributed inordinately to the spread of introgression. Because hybridized populations occurred across a full range of environmental conditions, I do not predict that abiotic conditions (i.e., cold water, late-stream flow, high elevations, or small stream size) will prevent the spread of hybridization in the long-term. As such, management interventions are recommended in chapter 4 and 5. I developed a simple taxonomic key to identify hybrids and guide selective removal efforts (Chapter 4). Additionally, I used volunteer angler surveys to estimate that recreational anglers visiting the watershed (~10,000 per year) could likely harvest a substantial number of non-native trout that would contribute to genetic management goals. I conclude by providing recommendations for management and monitoring (Chapter 5).Item Sampling and analysis techniques and their application for estimating recruitment of juvenile rainbow trout in the Henrys Fork of the Snake River, Idaho(Montana State University - Bozeman, College of Letters & Science, 1999) Mitro, Matthew GeorgeItem Effects of cattle grazing on upland nesting duck production in the Aspen Parkland(Montana State University - Bozeman, College of Letters & Science, 2004) Warren, Jeffrey Michael; Chairperson, Graduate Committee: Jay J. RotellaThe beef industry is growing rapidly throughout the Aspen Parkland of Canada, leading to higher stocking rates on pastures and use of previously idled areas. Conversely, increased demand for pastureland has led to conversion of cropland that may have benefited upland nesting ducks by increasing the amount of perennial cover. We undertook the current study to evaluate the relationships of nest-site selection and nesting success of upland-nesting ducks to cattle grazing in the Aspen Parkland. Nearly 4,000 ha of upland cover were searched during the study. Vegetation physiognomy was quantified at each nest and at random points within each field. Despite extensive drought, nest searches located 309 duck nests. Grazing demonstrated a strong negative effect on duck nest densities, as did declining pasture health. Our best model of nesting success indicated an interaction between nest-site vegetation and residual cover. Across most values of residual cover, nesting success was positively influenced by nest-site vegetation. However, at high values of residual cover, nest-site vegetation negatively affected nesting success. Other negative effects on nesting success included cattle presence and grassland area within a 1-km radius. Field-scale wetland area, however, demonstrated a positive relationship with nesting success. Although previous work has demonstrated higher nesting success in pastures than other habitats in the Aspen Parkland, our study is the first that we know of that investigated grazing intensity as a continuous factor along the gradient from idle to > 90 % utilization across a large number of fields (n = 97).Item Factors influencing the density and distribution of breeding waterfowl in North-Central Montana(Montana State University - Bozeman, College of Letters & Science, 2011) Fields, Sean Patrick; Chairperson, Graduate Committee: Jay J. RotellaContinental waterfowl population declines in the early 1980s led to the development and implementation of the North American Waterfowl Management Plan. The plan identified wetland and grassland losses in the Prairie Pothole Region (PPR) of Canada and the United States as the major causes of low continental duck populations. North-central Montana is the only remaining PPR area in the United States without a ground-based annual survey to monitor breeding duck populations and quantify breeding duck habitat. The purpose of this study was to establish an annual breeding duck survey in north-central Montana to 1) develop species-specific breeding pair predictive models, and 2) apply the models to estimate the density and distribution of breeding ducks and identify priority areas for conservation actions. 1969 indicated breeding duck pairs were observed on approximately 700 wetland basins in 2008 and 2009. A competing model analysis was used to identify local- and landscape-scale habitat characteristics to predict breeding duck pairs on wetland basins. The five most commonly observed species were modeled separately; those species were mallard (Anas platyrhynchos), northern pintails (A. acuta), gadwall (A. strepera ), northern shoveler (A. clypeata) and blue-winged teal (A. discors). At the local scale, wetland basin area, the square root transformation of wetland basin area and wetland basin class were important predictors for all species. Northern pintail, gadwall and blue-winged teal exhibited a strong location effect, occurring more in the northern and eastern portions of the study area. At the landscape scale, the proportion of agricultural lands surrounding a sample basin was associated with the greater abundance of all species. Northern pintail and blue-winged teal breeding pair abundance increased when the proportion of seasonal and semipermanent basin wetland surface area in the landscape around sample basin decreased. Results from this study provide land managers with initial information on where breeding waterfowl are settling across the PPR landscape of north-central Montana. The continuation of this research for several more breeding seasons will enable conservation partners to efficiently target important breeding waterfowl habitat for conservation actions.Item Assessing Weddell seal maternal investment in offspring(Montana State University - Bozeman, College of Letters & Science, 2011) Mannas, Jennifer Michelle; Chairperson, Graduate Committee: Robert A. GarrottReproduction is costly and involves a number of sequential physiological processes that require different levels of energetic investment. In mammalian species gestation and lactation require the most energy and the amount of energy invested in reproduction is reflected in litter size at birth and by offspring growth through weaning. The object of this study was to describe variation in Weddell seal (Leptonychotes weddellii) pup mass at birth and during several ages of the lactation/nursing period, and to evaluate the ability of several maternal traits to explain this variation. Mass measurements were collected from 887 pups at parturition and throughout lactation in Erebus Bay, Antarctica during the 2004 through 2010 field seasons and maternal traits were taken from a long term database. Analysis demonstrated high individual variation in pup mass within a season and modest variation among seasons which suggests that pup mass may be correlated with individual animal attributes rather than annual variation in environmental conditions. Maternal age, a female's reproductive status the previous season and their interaction were found to be the most influential maternal traits. Pup body mass at parturition and during lactation showed maternal age-related variation with evidence of senescence during pre-partum investment and terminal investment during post-partum investment. A female's reproductive status in one season affected her reproductive investment during lactation in consecutive seasons but that effect was correlated with age. Younger females who pupped in consecutive seasons weaned larger pups than those females who were of the same age and did not give birth in consecutive seasons. The opposite was found to be true for older females. The variation in the affect of maternal traits on maternal investment may be due to the increased energy requirement of lactation, age specific changes in reproductive costs, and a senescent decline in physiological function.Item Patterns of distribution and factors influencing riparian breeding birds along the Yellowstone River in Montana(Montana State University - Bozeman, College of Letters & Science, 2009) Jones, Danielle Ann; Chairperson, Graduate Committee: Andrew J. HansenRiparian zones harbor some of the most diverse bird communities. However, most riparian zones have been significantly modified by human activities. It is important to identify relationships between riparian birds and characteristics of the environment to understand the potential influences of floodplain management on birds. I examined patterns of riparian bird species distribution, as well as the factors affecting occurrence and abundance of species along the Yellowstone River in Montana. Point counts were conducted and vegetation data collected at 234 locations along 725 kilometers of the river. Occupancy or linear regression models were used to estimate occurrence or abundance of 14 bird species. First, I examined patterns in the distribution of bird species and their habitats. A gradient exists along most rivers that represents downstream changes in environmental conditions; I expected the distribution of vegetation to reflect this gradient, and birds to respond to these changing habitat conditions. Mature cottonwood habitat types were identified using cluster analysis, and habitat was an important driver of bird occurrence and abundance. However, there was little evidence that habitats were organized along a downstream gradient. River location was very important to birds, even after accounting for the influence of habitat, suggesting that the distributions of bird species are related to gradients that are not always reflected by habitat. Second, I used model selection methods to investigate the influences of local habitat, forest cover, land use, and river location on the occurrence or abundance of bird species. There was strong evidence that these factors were important drivers of bird distribution, and the relative influences of each factor depended upon life history characteristics of each species. The effect of river location on the occurrence or abundance of species suggests that broad-scale influences are important predictors of bird distribution along rivers. River location may reflect unmeasured environmental resources (e.g. food) that are important to birds, or variation in a species' distribution within its range boundaries. The Yellowstone River may serve as a reference for understanding the factors influencing the distribution of birds along a river, and provide valuable information for the management of riparian species.