Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
20 results
Search Results
Item Effects of de-snaring on the demography and population dynamics of African lions(Montana State University - Bozeman, College of Letters & Science, 2023) Banda, Kambwiri; Chairperson, Graduate Committee: Scott CreelLions and other African large carnivores are in decline, due in part to effects of illegal hunting with snares, which can reduce prey availability and directly kill or injure carnivores. It is difficult to effectively remove snares from large ecosystems by patrolling, but an additional approach to reduce effects on large carnivores is to monitor the population closely and de-snare individuals who are found in a snare or have broken free but still carry the wire (often with serious injury). The effectiveness of de-snaring programs to reduce impacts on large carnivores has not been directly tested. Here, we used long-term demographic data from 386 individually identified lions in the Luangwa Valley Ecosystem to test the effects on population growth (lambda) and population size (N) of a program to remove snares from injured lions and treat their wounds. Stochastic Leslie matrix projections for a period of five years showed that the population grew with the benefits of de-snaring but was expected to decline without de-snaring. Mean annual growth (lambda) was 1.037 (growth in 70% of years), closely matching observed changes in population size. Mean annual growth was 0.99 (with growth in 47% of years) for a model that assumed snared animals would have died if not treated, and 0.95 (with growth in 37% of years) for models that also accounted for super-additive effects via the death of dependent cubs and increased infanticide with increased male mortality. De-snaring requires intensive effort, but it can appreciably reduce the effect of snaring on lion population dynamics.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 African wild dog demography in an ecosystem with reduced prey and dominant competitors(Montana State University - Bozeman, College of Letters & Science, 2021) Goodheart, Benjamin Michael; Chairperson, Graduate Committee: Scott Creel; Scott Creel, Matthew S. Becker, Milan Vinks, Kambwiri Banda, Carolyn Sanguinetti, Paul Schuette, Elias Rosenblatt, Chase Dart, Anna Kusler, Kim Young-Overton, Xia Stevens, Alstone Mwanza and Chuma Simukonda were co-authors of the article, 'Low apex carnivore density does not release a subordinate competitor when driven by prey depletion' in the journal 'Biological conservation' which is contained within this thesis.Conservation of competitively subordinate carnivores presents a difficult challenge because they are limited by dominant competitors. Prey depletion is one of the leading causes of large carnivore decline worldwide, but little is known about the net effect of prey depletion on subordinate carnivores when their dominant competitors are also reduced. African wild dogs are often limited by high densities of dominant competitors, particularly lions. We measured African wild dog density and survival, using mark-recapture models fit to 8 years of data from 425 known individuals in the Greater Kafue Ecosystem, Zambia. The GKE is affected by prey depletion, particularly of large herbivores, and thus the density of lions is significantly lower than ecologically comparable ecosystems. Counter to expectations from mesopredator release theory, wild dog density in GKE was far lower than comparable ecosystems with higher lion and prey density, though annual survival rates were comparable to large and stable populations. Average pack size was small and home range size was among the largest recorded. Our results show that low lion density did not competitively release the GKE wild dog population and we infer that the low density of wild dogs was a product of low prey density. Our results suggest that there is an optimal ratio of prey and competitors at which wild dogs achieve their highest densities. This finding has immediate implications for the conservation of the endangered African wild dog, and broad implications for the conservation of subordinate species affected by resource depletion and intraguild competition.Item Vital rates, annual abundance, and movement of white sharks in the northeastern Pacific(Montana State University - Bozeman, College of Letters & Science, 2020) Kanive, Paul Edward; Chairperson, Graduate Committee: Jay J. Rotella; Jay J. Rotella, Salvador J. Jorgensen, Taylor K. Chapple, James E. Hines, Scot D. Anderson, Barbara A. Block were co-authors of the article, 'Size-specific apparent survival rate estimates of white sharks using mark-recapture models' in the journal 'Canadian journal of fisheries and aquatic sciences' which is contained within this dissertation.; Jay J. Rotella, Taylor K. Chapple, Scot D. Anderson, Timothy White, Barbara A. Block and Salvador J. Jorgensen were co-authors of the article, 'Estimation of regional annual abundance and evidence for increasing numbers of white sharks off California' which is contained within this dissertation.; Jay J. Rotella, Taylor K. Chapple, Scot D. Anderson, Mauricio Hoyos-Padilla, Barbara A. Block, Salvador J. Jorgensen were co-authors of the article, 'Connectivity between the central California and Guadalupe Island white shark populations' which is contained within this dissertation.Reliable estimates of populations' vital rates and abundance are fundamental requirements for making assessments and informed management decisions regarding any species. For large marine fish species whose movements are extensive throughout ocean basins, data for individuals are difficult to acquire. Without empirical data, large assumptions must be made about a species' vital rates (i.e. survival and fecundity) to make population assessments, which can potentially lead to erroneous results. Using mark-recapture and acoustic-telemetry data, I conducted analyses estimating vital rates, annual abundance, and coastal movement for white sharks (Carcharodon carcharias) off California, US. First, I used a novel approach to estimate size-specific annual apparent survival rates and to test for differences in survival between sexes after accounting for imperfect sex assignment. Our results provide little evidence for differences in sex-specific survival rates. However, I estimated the first size-specific annual apparent survival rates for sub-adult and adult white sharks. Second, I estimated annual abundance for four white shark demographic groups off the coast of California over an eight-year study period. The estimated total annual population of sub-adult and adult white sharks increased from 180 to 266 individuals during the study. Additionally, group-specific population growth rate point estimates were all > 1.00, which indicates that all groups had positive annual positive growth during the study period, although, uncertainty around those estimates were greater for sub-adults than adults and does not rule out other possibilities for population trajectories. Finally, through collaboration between Mexico and the US, I was able to analyze a comprehensive acoustic telemetry dataset that explored connectivity between two main aggregation sites that form the northeastern Pacific population of white sharks. I found that movement between the two regions was rare and more probable to be sub-adult sharks. These analyses underscore the value of collecting and analyzing empirical data to develop reliable estimates of vital rates for a top marine predator. The work also illustrates the ongoing need to cultivate international research collaboration to include data from both the US and Mexico to make accurate population inferences for the northeastern Pacific population of white sharks.Item Assessment of variation in the detection and prevalence of blood parasites among sympatrically breeding geese in western Alaska(Montana State University - Bozeman, College of Letters & Science, 2021) Buchheit, Raymond Matthew; Chairperson, Graduate Committee: Jay J. Rotella; Joel A. Schmutz, Brian Uher-Koch and Andrew M. Ramey were co-authors of the article, 'Assessment of variation in the detection and prevalence of blood parasites among sympatrically breeding geese in western Alaska' submitted to the journal 'Journal of wildlife diseases' which is contained within this thesis.Haemosporidian parasites may impact avian health and are subject to shifts in distribution and abundance with changing ecological conditions. Therefore, understanding variation in parasite prevalence is important for evaluating biologically meaningful changes in infection patterns and associated population level impacts. Previous research in western Alaska indicated a possible increase in Leucocytozoon infection between emperor geese (Anser canagicus) sampled in 1996 (<1%, n=134), and during 2011-2012 (19.9%, 95% CI: 3.0-36.8%, n=77); however, different detection methods were used for these estimates. Prior research in this same region identified a lack of Leucocytozoon parasites (0%, n=117) in sympatrically breeding cackling geese (Branta hutchinsii minima) in 2011. In this study, we molecularly screened blood samples collected from sympatrically breeding emperor and cackling geese in western Alaska during additional breeding seasons to better assess temporal and species-specific variation in the prevalence of blood parasites. We found similar prevalence estimates for Leucocytozoon parasites in emperor goose blood samples collected in 1998 and 2014, suggesting consistent infection of emperor geese with blood parasites at these time points. Using samples from sympatric geese sampled during 2014, we found evidence for higher incidence of Leucocytozoon parasites among emperor geese (20.3%, 95% CI: 11.8-32.7%) as compared to cackling geese (3.6%, 95% CI: 1.1-11.0%) reinforcing the previous finding of species-specific differences in infection. Furthermore, we detected Leucocytozoon, Haemoproteus, and Plasmodium blood parasites in unflighted goslings of both species, supporting the possible transmission of these parasites at western Alaska breeding grounds. Our results help to clarify that prevalence of Leucocytozoon parasites have likely remained consistent among emperor geese breeding in western Alaska since the late 1990s and that this species may disproportionally harbor Leucocytozoon parasites as compared to sympatrically breeding cackling geese.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 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 Environmental correlates of reproduction, patterns of maternal allocation, and variation in adult female vital rates in the Weddell seal(Montana State University - Bozeman, College of Letters & Science, 2017) Paterson, John Terrill; Chairperson, Graduate Committee: Jay J. Rotella; Jay J. Rotella, Kevin R. Arrigo and Robert A. Garrott were co-authors of the article, 'Tight coupling of primary production and marine mammal reproduction in the Southern Ocean' in the journal 'Proceedings of the Royal Society B' which is contained within this thesis.; Jay J. Rotella, Jennifer M. Mannas and Robert A. Garrott were co-authors of the article, 'Patterns of age-related change in reproductive effort differ in the prenatal and postnatal periods in a long-lived mammal' in the journal 'Journal of animal ecology' which is contained within this thesis.; Jay J. Rotella, William A. Link and Robert A. Garrott were co-authors of the article, 'Variation in the vital rates of an antarctic marine predator: reproductive costs, age-related changes, and individual heterogeneity' submitted to the journal 'Journal of animal ecology' which is contained within this thesis.The dynamics of populations are the integrated result of multiple processes affecting variation in vital rates. Using a long-term mark-recapture dataset from a population of Weddell seals (Leptonychotes weddellii) in Erebus Bay, Antarctica, I investigated three processes related to population dynamics: environmental correlates of reproduction, sources of variation in maternal allocation to offspring, and sources of variation in the vital rates of adult females. First, I assessed the strength of the association between primary production in the McMurdo Sound and Ross Sea polynyas and the number of pups born in Erebus Bay. I demonstrated both a strong coupling between trophic levels and a surprising timing in the relationship. Pup numbers were most strongly associated with primary production in the months after birth, consistent with a response by mothers to take advantage of the environment of relative abundance. Second, I showed that the patterns of maternal allocation to offspring differ in the prenatal and post-parturition periods. Maternal and pup masses at parturition increased with maternal age (maximum near age 16) prior to declining for older animals, consistent with both restraint and senescence. In contrast, maternal allocation to offspring continued to increase with maternal age during the post-parturition period. Together, these patterns are strong evidence for terminal allocation. Furthermore, I found extensive among-individual heterogeneity, such that some mothers consistently produce heavier pups and allocate more resources during lactation. Finally, I assessed the sources of variation in the vital rates of adult females, using a multistate model to jointly estimate the probabilities of survival and reproduction. Survival rates steadily declined with age, consistent with the onset of senescence at the age of first reproduction, whereas reproductive rates increased for young animals to a maximum 8 years after the age of first reproduction before exhibiting a senescent decline. I found extensive among-individual and yearly variation in reproductive rates, coupled to minimal variation in survival rates. This dissertation adds novel information to the understanding of the complex demography of Weddell seals by revealing an association between trophic levels and patterns of variation in both the allocation of resources to offspring as well as vital rates of adult females. Together, these results shed further light on the flexible life-history patterns of a long-lived marine mammal.Item Harvest, nasal-markers, and lesser scaup vital rates(Montana State University - Bozeman, College of Letters & Science, 2017) Deane, Cody Earle; Chairperson, Graduate Committee: Jay J. RotellaSince the mid-1980s, lesser scaup (Aythya affinis) population abundance has been approximately 20% below the North American Waterfowl Management Plan goal of 6.3 million lesser adult lesser scaup. Sustained harvest opportunity of this species is an important management goal in North America. We examined the relationship between harvest mortality and survival rates for a breeding population in southwest Montana from 2005 to 2016 when Adaptive Harvest Management was implemented for lesser scaup. We combined resighting, recapture, and hunter recovery to estimate survival and harvest rates using multistate capture-mark-recapture models in Program MARK. Nasal-marker loss rates were substantial and accounted for by allowing resight detection probability to decay with nasal-marker age. Adult female survival rates tended to be positively related to an interaction between annual Pacific flyway lesser scaup harvest and this value divided by the Pacific flyway daily bag limit, which we used as an index for population density (beta INTERACTION = 0.168, SE = 0.091). Estimated annual survival rates for adult metal-banded females averaged 0.66 (SE = 0.03) and 0.49 (SE = 0.02) for adult nasal-marked females, while first-winter survival rates averaged 0.39 (SE = 0.03) for metal-banded juveniles and 0.23 (SE = 0.02) for nasal-marked juveniles. However, this decrease in survival rates is not attributable to differing harvest rates between nasal-marked and metal-banded females (beta NASAL-MARKED, HARVEST RATE = 0.101, SE = 0.166). Body condition of nasal-marked females did not differ from unmarked females as their residual body mass was 1.6 g (SE = 10.4 g) less during the pre-breeding season and 3.5 g (SE = 6.5 g) less during the brood-rearing period. Nasal-marked females were found to have delayed initiating nests by 3.6 days (SE = 1.9 days) and laid 0.5 fewer eggs (SE = 0.3 eggs) relative to unmarked females while they hatched ducklings weighing 0.2 g (SE 0.2 g) more than unmarked females. Nasal-marked females were harvested 154.9 km (SE = 112.5 km) further from the study site than unmarked females, suggesting nasal-markers don't impede migration ability. Cumulatively, our results for nasal-marker impacts on vital rates suggest substantial individual heterogeneity among individuals exists in this population.Item Factors affecting the size and distribution of large herbivores in Kafue National Park, Zambia(Montana State University - Bozeman, College of Letters & Science, 2016) Matandiko, Wigganson; Chairperson, Graduate Committee: Scott CreelThe distribution and abundance of African ungulates are limited by abiotic factors (soil nutrients and water), bottom-up processes (forage availability and density-dependent competition for food), top-down processes (direct predation and the costs of avoiding predation) and anthropogenic effects. The relative importance of biotic factors such as food limitation and predation have been well-studied for some species (e.g. wildebeest, Connochaetes taurinus), particularly in flagship ecosystems such as Serengeti and Kruger National Parks. Research on complete ungulate communities is needed to describe differences between ungulate species in the relative importance of these limiting factors, and how their importance varies across ecosystems. Moreover, ungulate populations are in decline across much of Africa, and research is needed to examine the importance of anthropogenic effects and the manner in which anthropogenic effects alter the strength of other limiting factors. Here, we used line transect data collected over three years to estimate population densities and determine what factors limit the distribution of large herbivores in Kafue National Park - North (KNP - N) of Zambia, in Southern Africa. With temporal replication within and among years, we sampled a set of systematically distributed transects, and used distance sampling models to correct for non-detection and test the effects on ungulate distributions of vegetation type, grass height and color, recent burning, distance to rivers and lagoons, soil type, pH and nutrients, lion use, and the distance to roads, tourist camps, and park boundaries. Our results show that the most abundant large herbivores in KNP are impala (Aepyceros melampus), puku (Kobus vardonii) and warthog (Phacochoerus africanus). Using AIC scores to test a set of distance sampling models, we found substantial variation among species in the relative importance of abiotic, bottom-up, top-down and anthropogenic effects. These results suggest that a range of species-specific strategies may be needed to conserve African large herbivores and ameliorate recent declines.