Theses and Dissertations at Montana State University (MSU)
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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 Spatial ecology of mountain ungulates in the northern Rocky Mountains: range expansion, habitat characteristics, niche overlap, and migratory diversity(Montana State University - Bozeman, College of Letters & Science, 2018) Lowrey, Blake Henson; Chairperson, Graduate Committee: Robert A. Garrott; Robert A. Garrott, Hollie M. Miyasaki, Gary Fralick and Sarah R. Dewey were co-authors of the article, 'Seasonal resource selection by introduced mountain goats in the southwest greater Yellowstone area' in the journal 'Ecosphere' which is contained within this thesis.; Robert A. Garrott, Doug E. McWhirter, P.J. White, Nicholas J. DeCesare and Shawn T. Stewart were co-authors of the article, 'Niche similarities among introduced and native mountain ungulates' in the journal 'Ecological applications' which is contained within this thesis.; Kelly M. Proffitt, Douglas E. McWhirter, P. J. White, Alyson B. Courtemanch, Sarah R. Dewey, Hollie M. Miyasaki, Kevin L. Monteith, Julie S. Mao, Jamin L. Grigg, Carson J. Butler, Ethan S. Lula and Robert A. Garrott were co-authors of the article, 'Contrasting seasonal movements in native and restored populations: a case for conserving migratory portfolios' submitted to the journal 'Journal of applied ecology' which is contained within this thesis.; Douglas E. McWhirter, Kelly M. Proffitt, Alyson B. Courtemanch, Kevin L. Monteith, P. J. White, J. Terrill Paterson, Sarah R. Dewey and Robert A. Garrott were co-authors of the article, 'Individual variation creates diverse portfolios of seasonal movement patterns and ranges in a migratory ungulate' submitted to the journal 'Ecology' which is contained within this thesis.Mountain ungulates, although recognized as iconic and charismatic wildlife species, are the least studied and understood large mammals in western North America. The paucity of data, specifically concerning spatial ecology, presents a formidable challenge to regional wildlife managers tasked with the responsibility of managing populations with limited empirical studies on which to base decisions. We used GPS data collected from bighorn sheep (Ovis canadensis) and mountain goats (Oreamnos americanus) sampled from multiple populations throughout the northern Rocky Mountains to develop comparative studies characterizing seasonal habitats and potential range expansion of introduced mountain goats, niche overlap with native bighorn sheep, and migratory diversity of restored, augmented, and native bighorn sheep. Slope was the dominant predictor of mountain goat habitat use in both seasons, although mountain goats selected for steeper slopes in winter than in summer. Regional extrapolations depicted suitable mountain goat habitat in the Snake River, Teton, Gros Ventre, Wyoming and Salt Ranges centered around steep and rugged areas. Although bighorn sheep occurred on steeper slopes than mountain goats in summer and mountain goats occurred on steeper slopes in winter, we observed broad niche overlap according to season-species niche models and observed GPS locations where the two species were sympatric. In native bighorn sheep herds, we observed longer migrations on average and significantly more variation among individuals when compared to restored herds. The enhanced individual variation in native herds resulted in diverse portfolios of migratory behaviors and ranges, including newly documented high elevation long-distance migrants, increased switching rates between migratory behaviors, and sub-populations that were diffusely spread across both summer and winter ranges. In contrast, restored herds had limited individual variation, were largely non-migratory, had less switching between years, and were generally concentrated on both summer and winter ranges. In addition to increasing the abundance and distribution of bighorn sheep on the landscape, we suggest there may be value in simultaneously increasing the diversity of seasonal movement strategies, and in so doing, building resilience to future perturbations and disease, and mirroring the movement portfolios observed in native populations of bighorn sheep.Item Assessing respiratory pathogen communities and demographic performance of bighorn sheep populations: a framework to develop management strategies for respiratory disease(Montana State University - Bozeman, College of Letters & Science, 2017) Butler, Carson Joseph; Chairperson, Graduate Committee: Robert A. GarrottRespiratory disease (pneumonia) is a persistent challenge for bighorn sheep (Ovis canadensis) conservation as sporadic epizootics cause up to 90% mortality in affected populations and are often followed by numerous years of low juvenile recruitment attributed to lamb pneumonia. Domestic sheep (Ovis aries) and domestic goats (Capra aegagrus hircus) are the origin of the disease and asymptomatically carry respiratory pathogens that cause respiratory disease when introduced to bighorn sheep. Pathogens that have been linked to respiratory disease in bighorn sheep include several species of bacteria in the Pasteurellaceae family and another bacterial species, Mycoplasma ovipneumoniae. Despite substantial efforts by management agencies to prevent contact between bighorn sheep and domestic sheep and goats, respiratory disease epizootics continue to affect bighorn sheep populations across much of their distribution with uncertain etiology. This study sought to investigate efficacy of diagnostic protocols in detecting Pasteurellaceae and Mycoplasma ovipneumoniae and generate sampling recommendations for different protocols, assess the distribution of these disease agents among 17 bighorn sheep populations in Montana and Wyoming and evaluate what associations existed between detection of these agents and demographic performance of bighorn sheep populations. Analysis of replicate samples from individual bighorn sheep revealed that detection probability for regularly-used diagnostic protocols was generally low (<50%) for Pasteurellaceae and was high (>70%) for Mycoplasma ovipneumoniae, suggesting that routine pathogen sampling likely mischaracterizes respiratory pathogen communities. Power analyses found that most pathogen species could be detected with 80% confidence at the population-level by conducting regularly-used protocols multiple times per animal. Each pathogen species was detected in over half of the study populations, and consideration of detection probability discerned that there was low confidence in negative test results for populations where the Pasteurellaceae species were not detected. 76% of study populations hosted Mycoplasma ovipneumoniae and Pasteurellaceae pathogens, yet a number of these populations were estimated to have positive population growth rates and recruitment rates greater than 30%. Overall, the results of this work suggest that bighorn sheep respiratory disease may be mitigated by manipulating population characteristics and respiratory disease epizootics could be caused by pathogens already resident in bighorn sheep populations.Item Population dynamics of bighorn sheep on the Beartooth Wildlife Area, Montana(Montana State University - Bozeman, College of Letters & Science, 1999) Enk, Terrence A.Item Development of occupancy surveys for mountain ungulates(Montana State University - Bozeman, College of Letters & Science, 2013) O'Reilly, Megan; Chairperson, Graduate Committee: Robert A. GarrottBighorn sheep (Ovis canadensis canadensis) and mountain goats (Oreamnos americanus) overlap in broad food and habitat requirements. In places where mountain goats are non-native there are concerns over potential competition between the two species. The southern Gallatin Mountain range, within and adjacent to the northwest boundary of Yellowstone National Park has both native bighorn sheep and non-native mountain goats. Existing observations of both species for this area vary in spatial precision and there are no records of where observers looked for animals but did not detect them. To gain a better understanding of the relationship between bighorn sheep and mountain goats and their habitat, it is necessary to understand resource selection and the extent of overlap in resource use at fine spatial and temporal scales. I used logistic regression to relate existing presence-only bighorn sheep and mountain goat data for this area to landscape features I expected would be important to both species. Using resulting coefficient estimates, I constructed a relative habitat suitability map and used it to define four survey regions within the study area. The crew of four spent 113 observer days afield and hiked 210 miles recording occupancy data for both mountain ungulates within these four survey regions. Observers surveyed 6,603 100 x 100 meter grid cells, with 15 groups of bighorn sheep and 34 groups of mountain goats observed during surveys. Because there were more mountain goat observations available, I used only mountain goat data to conduct formal occupancy analyses. Mountain goat occupancy was positively associated with ruggedness at the 100 meter scale and there was an important interaction between distance to escape terrain and tree cover at the 500 meter scale. As the distance to escape terrain increased mountain goats were less likely to occupy treed areas. The ruggedness index used in my presence-only modeling effort was based on the rate of change in slope. By using a ruggedness index which included changes in slope and aspect I improved model performance. This research demonstrates the feasibility of conducting occupancy surveys in mountainous terrain and provides interesting biological insights regarding mountain goats and their habitat.Item Impacts of human activity on bighorn sheep in Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 1998) Ostovar, Kayhan; Chairperson, Graduate Committee: Lynn R. IrbySeventeen years have passed since bighorn sheep (Ovis canadensis canadensis) in Yellowstone National Park (YNP) experienced a massive Chlamydial-caused die-off. Currently, no sign of Chlamydia or pneumonia is evident, thus other factors are considered to be limiting the population. The proposed changes to the Gardiner-Mammoth highway and the highway through Dunraven Pass could increase or decrease human disturbances to the core population of bighorn sheep. Approximately 65% of all observations on the Everts winter range occurred on the top of McMinn Bench (along the proposed road route). One ewe group currently must cross the Gardiner-Mammoth highway to reach spring lambing grounds. The placement of the road onto McMinn Bench would impact at least 2 other populations of ewe groups and 2-3 populations of ram groups, which seek shelter, security, water, and minerals in the cliffs.