Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Testing the effects of anthropogenic pressures on African lions and their prey in the Greater Kafue Ecosystem, Zambia(Montana State University - Bozeman, College of Letters & Science, 2020) Vinks, Milan Alexander; Chairperson, Graduate Committee: Scott Creel; Scott Creel, Paul Schuette, Wigganson Matandiko, Elias Rosenblatt, Carolyn Sanguinetti, Kambwiri Banda, Ben Goodheart, Matthew S. Becker, Clive Chifunte, and Chuma Simukonda were co-authors of the article, 'Testing the effects of anthropogenic pressures on a diverse African herbivore community' in the journal 'Ecosphere' which is contained within this thesis.; Scott Creel, Paul Schuette, Matthew S. Becker, Elias Rosenblatt, Carolyn Sanguinetti, Kambwiri Banda, Ben Goodheart, Kim Young-Overton, Xia Stevens, Clive Chifunte, Neil Midlane, and Chuma Simukonda were co-authors of the article, 'Response of lion demography and dynamics to the loss of prey and changes in prey community composition' submitted to the journal 'Ecological Applications' which is contained within this thesis.Rapid human population growth across Africa has put tremendous pressure on large herbivore and large carnivore populations, and most of these large terrestrial species are now limited to residing within or adjacent to protected area (PA) networks. However, high rates of human encroachment and associated activities around and within PAs are jeopardizing their effectiveness and have become a major conservation concern. High rates of illegal harvest are linked to human encroachment and can have devastating effects on large herbivore and large carnivore populations. Large herbivore declines are often greatest in areas with high rates of illegal offtake and ensuing prey depletion can be a primary driver of large carnivore declines. Kafue National Park (KNP) of central Zambia supports a diverse large herbivore community and the country's second largest lion population. However, KNP is thought to be experiencing human-caused wildlife declines, providing a unique opportunity to evaluate anthropogenic effects on both the large herbivores and large carnivores of this system. Here, we evaluated the status and major anthropogenic and environmental drivers of KNP's large herbivore populations and lion population. First, we estimated population densities and distribution of the ten most abundant large herbivore species using stratified ground-based surveys conducted from 2012 - 2018. These data indicated that population densities were consistently low across species and areas, though there was ecologically important variation among species and size classes. Moreover, densities of larger-bodied herbivores were greatly depressed relative to smaller species. Second, we evaluated population density, survival rates, and demography for the KNP lion population from 2013 - 2018. These data indicated that age- and sex-specific survival rates for settled individuals were generally high, and factors known to correlate with local prey density had small effects on lion survival. In contrast, average lion density was low and recruitment of cubs was poor. These findings suggest that low recruitment might be a better signal of low prey density than survival. Overall, large herbivores and lions appear to be limited by human activities in KNP. Increased resource protection and reducing the underlying drivers of prey depletion are urgent conservation needs to facilitate the recovery of these economically and ecologically valuable species.Item Biophysical gradients and performance of whitebark pine plantings in the Greater Yellowstone Ecosystem(Montana State University - Bozeman, College of Letters & Science, 2019) Laufenberg, David Anton; Chairperson, Graduate Committee: Andrew J. HansenThe efficacy of planting efforts for species of conservation interest is important for ecosystem managers. Planting efforts represent an opportunity to conserve and manage species during a population crisis. Although federal agencies have been planting whitebark pine (WBP) in the Greater Yellowstone Ecosystem (GYE) for three decades, these efforts have been met with varying success. In this study, we use a combination of field sampling and remote sensing approaches in order to investigate local biophysical gradients as explanatory variables for WBP performance in GYE planting units. Present-day field sampling affords an opportunity to evaluate WBP performance relative to earlier planting and monitoring records. We used remotely-sensed temperature and precipitation alongside field measurements of elevation, aspect, slope, shading, and soils to utilize an adapted Thornthwaite-type water balance model to explain individual growth rates and site density change ratios (essentially survival and natural recruitment). We found that planting sites varied greatly in their biophysical characteristics and WBP performance. Five of twenty-nine sites had higher present-day density than at date of planting, therefore indicating some amount of natural regeneration occurring within those sites since time of planting. These sites were often higher in elevation, not south or southwest facing, and had soils that could hold moisture later in the season and for longer periods following precipitation events. Sites that experienced reductions in the density of WBP were often lower in elevation, with poorer soils, and facing south or southwest. They therefore experience greater potential evapotranspiration, and also greater water deficit when water demands are not being met. Notably, our two response variables, individual growth rate and site density change ratio represent short and long-term performance variables respectively. Although our results suggest that individual growth rates are likely more often limited by energy than water demands, the site density change ratio associated with this late to mature, long-lived species is likely a better benchmark for success. If they make it to maturity, trees planted this season will not begin to produce cones until the end of this century or the beginning of the next. Therefore, they must overcome forecasted periods of greater water stress in the coming decades and centuries. We strongly recommend planting efforts that seek to reduce the effects of increased drought stress by planting at sites with soils of greater water holding capacities (non-rhyolitic), planting on northerly and easterly aspects, and utilizing microsites particularly when planting at sites with potentially higher water stress. We also detected a negative relationship between the density of local competitors and WBP performance, but only at higher densities. Ecosystem managers will continue to plant WBP in the GYE for years to come, and this research helps to inform and identify high quality habitat during a period of changing climate and high GYE WBP mortality rates.Item Estimating apparent survival of sub-adult and adult white sharks (Carcharodon carcharias) in central California using mark-recapture methods(Montana State University - Bozeman, College of Letters & Science, 2013) Kanive, Paul Edward, Jr.; Chairperson, Graduate Committee: Jay J. RotellaOver-exploitation of sharks is a global conservation concern as losses of large apex predators will likely lead to negative consequences in marine ecosystems. The Northeastern Pacific white shark population is genetically distinct and geographically isolated from other known white shark populations in South Africa, Australia/New Zealand, and the Northwest Pacific. The Northeastern Pacific population/clade is comprised of two groups, Guadalupe Island, Mexico, and Central California, USA, that predictably aggregate at their respective coasts during late summer to early winter months. Recently, a three-year study using patterns on the trailing edge of dorsal fins to identify unique white sharks estimated an abundance of 219 (95% credible interval of 130 to 275) sub-adult and adult white sharks off Central California, assuming a closed population. However, there are no estimates for any of the population's vital rates (e.g. survival, recruitment rates). We use six years of mark-recapture data to estimate apparent survival and test for differences in survival between sexes for sub-adult and adult white sharks in central California. We collected 668 photographs that allowed us to identify 199 individual sharks over six years of sampling at three locations off Central California. Using a method developed by Nichols et al. (2004) that accounts for imperfect detection and imperfect sex assignment, we estimated that annual apparent survival was 0.90 (95% CI = 0.81 - 0.98) for males and females and throughout our study period. At this time, it is difficult to determine how this vital rate will affect population trend. Future research is needed to determine if this annual survival estimate is high enough for adult white sharks to produce enough offspring that will eventually recruit to the sub-adult demographic to balance annual mortality.