Theses and Dissertations at Montana State University (MSU)
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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 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 Spatiotemporal covariates, individual characteristics, and mountain lion harvest as potential sources of variation in elk calf survival(Montana State University - Bozeman, College of Letters & Science, 2019) Forzley, Michael James; Chairperson, Graduate Committee: Jay J. RotellaTo understand the efficacy of increasing the harvest of large carnivores for increasing elk calf survival, we compared calf survival data collected from two elk herds before, during, and after a mountain lion harvest treatment which consisted of increases in prescribed mountain lion harvest quotas. We collected survival data from 534 radio-tagged elk calves in both the East Fork and West Fork herds of the upper Bitterroot Valley of west-central Montana. We used these data and time-to-event analyses to estimate the annual rates of survival and cause-specific mortality for elk calves in the study, as well as estimate the relationships between elk calf survival and several factors previously related to variation in annual elk calf survival. Average annual rates of survival for female calves before the mountain lion harvest treatment (pre-treatment era) were 0.38 (95% CI = 0.00-0.54) in the West Fork herd, and 0.37 (95% CI = 0.09-0.65) in the East Fork herd. Annual rates of survival for female calves during the harvest treatment (during-treatment era) were 0.65 (95% CI = 0.47-0.83) in the West Fork herd and 0.65 (95% CI = 0.46-0.87) in the East Fork herd. Annual rates of survival for female calves 4-5 years post-harvest treatment (post-treatment era) were 0.46 (95% CI = 0.31-0.61) in the West Fork herd and 0.47 (95% CI = 0.32-0.62) in the East Fork herd. Survival of male calves followed a similar pattern. Rates of mountain lion predation were highest in the pre-treatment era, moderate in the during-treatment era, and lowest in the post-treatment era. However, decreased rates of mountain lion predation following mountain lion harvest treatment coincided with increased probability of non-predation related mortality, and short-term changes in annual elk calf survival. Our results suggest that mountain lion harvest management prescriptions designed to achieve moderate, short-term reductions in mountain lion population abundance may be effective in allowing for short-term increases in elk calf recruitment and may be an effective management tool to increase calf recruitment.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.Item Status of northern pearl dace and chrosomid dace in prairie streams of Montana(Montana State University - Bozeman, College of Letters & Science, 2018) Stringer, Allison Louise; Chairperson, Graduate Committee: Alexander V. ZaleNon-native Northern Pike Esox lucius are predators that negatively affect native fish assemblages, possibly including those in Montana prairie streams, where their effects had not been investigated heretofore. I compared fish assemblages of prairie streams with and without Northern Pike and other non-native predators, with a focus on three species of concern that are probably particularly susceptible to predation (Northern Pearl Dace Margariscus nachtriebi (hereafter pearl dace), Northern Redbelly Dace Chrosomus eos, and Northern Redbelly Dace x Finescale Dace hybrids C. eos x C. neogaeus [hereafter hybrid dace]). I documented fish assemblages at 140 sites across the historical distribution of Northern Redbelly Dace and hybrid dace (hereafter collectively referred to as chrosomid dace), including 88 sites in the historical distribution of pearl dace. I estimated percent declines in distribution by comparing the number of currently occupied historical streams with the total number of historical streams and then determined if cooccurrence of pearl dace or chrosomid dace with non-native predators was different than predicted by chance. I augmented my dataset with fish collections from 5 additional sources and evaluated whether sites with and without Northern Pike differed in native species richness (with a Poisson regression) or assemblage composition (with a discriminant function analysis). Pearl dace distribution declined 63.3 to 83.3%, and chrosomid dace distribution declined 32.0% to 67.2%, depending on how declines were calculated. Pearl dace almost never co-occurred with Northern Pike or non-native trout and chrosomid dace rarely co-occurred with them. Native minnow species richness was 52% lower at sites with Northern Pike than at sites without Northern Pike. Predation probably caused the observed changes. Pearl dace are at extreme risk and chrosomid dace are at moderate risk of extirpation from Montana, and non-native predators appear to be the biggest threat to their continued persistence. Exclusion of Northern Pike from drainages where they have not yet invaded will afford fisheries managers the best chance of conserving native minnows in Montana prairie streams.Item Risky business: dealing with risk in a predator - prey community(Montana State University - Bozeman, College of Letters & Science, 2017) Droge, Egil Dag; Chairperson, Graduate Committee: Scott Creel; Scott Creel, Matthew S. Becker and Jassiel M'soka were co-authors of the article, 'Spatial and temporal avoidance of risk within a large carnivore guild - predator avoidance by predators' in the journal 'Ecology and evolution' which is contained within this thesis.; Scott Creel, Matthew S. Becker and Jassiel M'soka were co-authors of the article, 'Measuring the 'landscape of fear': risky times and risky places interact to affect the response of prey' in the journal 'Ecology and evolution' which is contained within this thesis.; Scott Creel, Matthew S. Becker, David A. Christianson and Fred G.R. Watson were co-authors of the article, 'Response of wildebeest (Connochaetes taurinus) movements to spatial variation in long term risks from a complete predator guild' which is contained within this thesis.The Liuwa ecosystem has several ecological properties that affect interactions among large predators, with lions and hyaenas as dominant species and African wild dog and cheetah as subordinate species, and between predator and prey. First, the vegetation structure is highly uniform and typified by open grasslands with good visibility over long distances. Secondly the prey community is heavily dominated by wildebeest, with much lower numbers of zebra, oribi and other species. These characteristics combined with GPS data on a fine spatial scale, and a large observational dataset on both predators and prey enabled us to focus on several little-studied questions about the effects of predation risk in the wild. Interspecific competition between predators can be a strongly limiting force for subordinate predators like cheetahs and African wild dogs. Both species use niche partitioning to reduce the risk of dangerous interactions in different ways that appear to have ramifications for coexistence. Wild dogs showed more dietary and temporal overlap with dominant competitors while cheetahs combine divergence in diet, temporal avoidance and reactive local spatial avoidance to coexist with lions and hyenas in areas of high prey density, even in open habitats. These results provide new insight into the conditions under which partitioning may not allow for coexistence of African wild dog, while it does for cheetah, with dominant predators making wild dogs more prone to competitive exclusion (local extirpation), particularly in open, uniform ecosystems with simple prey communities. Focusing on predator-prey relationships the overall the conclusion is that the assessment of risk by animals is a very fine-tuned process. Our results confirm that both the risky places hypothesis (LT risk) and the risky times hypothesis (ST risk) are important, leading to both reactive and proactive responses. Critically, these effects do not act independently in their effects on the strength of antipredator responses. This interaction presents challenges for the design of research on risk effects. An effect of ST risk could be masked by unmeasured variation in LT risk (or vice versa), and an effect of ST risk might be caused by unmeasured variation in LT risk (or vice versa).Item Some observations on the predator-prey complex in the Gallatin valley(Montana State University - Bozeman, College of Agriculture, 1941) Haight, Cecil P.Item Predator-prey interactions between introduced trout and long-toed salamanders and ways to mitigate nonconsumptive effects(Montana State University - Bozeman, College of Letters & Science, 2014) Kenison, Erin Kennedy; Chairperson, Graduate Committee: Andrea Litt; Andrea R. Litt, David S. Pilliod and Thomas E. McMahon were co-authors of the article, 'Nonconsumptive effects of introduced trout predators on long-toed salamanders: changes in morphology and life history' submitted to the journal 'Journal of herpetology' which is contained within this thesis.; Andrea R. Litt, David S. Pilliod and Thomas E. McMahon were co-authors of the article, 'Adding vegetation structure to reduce nonconsumptive effects of introduced trout: a novel method for amphibian conservation?' submitted to the journal 'Journal of herpetology' which is contained within this thesis.Predators can increase prey through mortality, but also have the capacity to alter behavior, morphology, and life history through nonconsumptive effects. In many historically fishless lakes in western North America, trout have been introduced for recreational fishing and are associated with reducing and extirpating populations of amphibians, including long-toed salamanders (Ambystoma macrodactylum). Salamanders and trout may coexist in some lakes, as larvae are able to alter foraging behavior by avoiding open water, foraging at night in shallow water, and hiding in cover to avoid predation. However, salamanders may experience nonconsumptive effects due to these behavioral changes. We sought to estimate the nonconsumptive effects of trout on morphology and life history of larval salamanders. We caught salamander larvae using minnow traps in northwestern Montana during the summers of 2012 and 2013 and compared body morphology measurements and size at and timing of metamorphosis between lakes with and without trout. Salamanders in lakes with trout were smaller: they weighed less, had shorter body lengths, and had shorter and narrower tails. Salamanders in lakes with trout were also less likely to metamorphose, did so later in the summer, and had smaller total and tail lengths at metamorphosis. These changes in morphology and life history likely were a result of reduced foraging to avoid predator attacks. We conducted a field experiment in 2013 to investigate whether adding vegetation structure could reduce nonconsumptive effects of trout on salamander larvae by providing refugia and reducing perceived risk of predation. We constructed field enclosures in lakes with and without trout and quantified changes in salamander growth and differences in size at metamorphosis with and without added structure. Salamanders appeared to detect trout cues because they grew more slowly in lakes with trout, even though trout had no ability to consume salamanders. Added vegetation structure did not influence growth rates, but did increase the probability of salamanders that reached metamorphosis. Future research efforts should investigate whether adding vegetation structure to whole lakes can mitigate the nonconsumptive effects of trout, provide a feasible alternative to fish removal, and facilitate coexistence between salamanders and trout.Item Factors affecting the distribution and abundance of carnivores and their ungulate prey across a communally owned rangeland in Kenya(Montana State University - Bozeman, College of Letters & Science, 2012) Schuette, Paul Anthony; Chairperson, Graduate Committee: Scott Creel; Aaron Wagner, Meredith Wagner and Scott Creel were co-authors of the article, 'Occupancy patterns and niche partitioning within a diverse carnivore community exposed to anthropogenic pressures' in the journal 'Biological conservation' which is contained within this thesis.; Scott Creel was a co-author of the article, 'Spatiotemporal niche partitioning among large carnivores, ungulates, people, and livestock in Southern Kenya' which is contained within this thesis.; Scott Creel and David Christianson were co-authors of the article, 'Factors affecting the distributions of native ungulates and livestock in Kenya's Rift Valley' in the journal 'Conservation biology' which is contained within this thesis.; Scott Creel and David Christianson were co-authors of the article, 'African lion abundance and space use in relation to a seasonally migrating human pastoralist community' in the journal 'Conservation biology' which is contained within this thesis.Carnivore and native ungulate populations are in decline inside and outside of government-protected areas in Africa due to habitat fragmentation, conversion of rangeland to farmland, and conflict. Though government-protected areas are an important component of conservation and management policy, it is also important to include landscapes that vary in their degree of protection and human land use. These mixed-use landscapes may provide valuable insight into patterns that promote coexistence among carnivores, native ungulates, and people. From 2008-2011, we examined distributions and abundances of carnivores and their ungulate prey across a communally-owned rangeland in the southern Rift Valley of Kenya. Here, the local Maasai community moves seasonally with their livestock across areas set aside for human settlement, livestock grazing, and a community conservation area. Camera surveys revealed a diverse carnivore community (21 species), which includes all native apex carnivores. Occupancy models revealed patterns of spatial and temporal niche partitioning in response to environmental conditions and anthropogenic pressures. Apex carnivore and native herbivore occupancies were sensitive to the proximity of water, the dry season, and distance to human settlements. In general, most carnivore and native herbivores responded to some form of human land use. Animal counts and distance sampling indicated livestock densities were nearly three times higher than total native ungulate densities, however, native ungulate densities were comparable to many government-protected areas. Selection of different habitats and land use types promoted coexistence between domestic and native ungulates. Zebra, wildebeest, and cattle (obligate grazers) densities were sensitive to a severe drought, but only wildebeest failed to rebound to pre-drought levels the following year. Behavioral follows of radio-collared lions (4F, 2M) revealed a local lion density of 0.136 individuals/km ², comparable to many government-protected areas. Lion groups altered their space use in response to seasonal movements of people, a pattern that likely explains low levels of local conflict. Overall, the combination of an unfenced, heterogeneous landscape and a land use system based on temporary settlements, seasonal grazing areas, and a community conservation area, allows apex carnivores, a diverse carnivore community, and their native ungulate prey to coexist at high densities with people and livestock.Item Applying risk allocation theory in a large mammal predator-prey system : elk-wolf behavioral interactions(Montana State University - Bozeman, College of Letters & Science, 2004) Gude, Justin Albert; Chairperson, Graduate Committee: Robert A. Garrott; Scott Creel (co-chair)Understanding the behaviorally-mediated indirect effects of predators in ecosystems requires knowledge of predator-prey behavioral interactions, and the risk allocation hypothesis can be used to make predictions about such interactions. In predator-ungulate-plant systems, empirical research quantifying how predators affect ungulate group sizes and distribution, in the context of other influential variables, is particularly needed. We determined non-predation variables that affect elk (Cervus elaphus) group sizes and distribution on a winter range in the Greater Yellowstone Ecosystem (GYE), using regression analyses of 1219 elk groups counted and mapped over 12 years prior to wolf (Canis lupus) recolonization. We next examined the relevance of these non-wolf-predation variables in the presence of wolves using logistic and linear regression on surveys of 513 1-km2 areas conducted over 2 years. Using model selection techniques, we evaluated risk allocation and other a priori hypotheses of elk group size and distributional responses to wolf predation risk while accounting for influential nonwolf- predation variables. We found little evidence that wolves affect elk group sizes, which were strongly influenced by habitat type. Following predictions from the risk allocation hypothesis, wolves likely created a more dynamic elk distribution in areas that they frequently hunted, as elk tended to move during the period of safety following wolf encounters in those areas. We predict that this distributional response to wolf predation risk should decrease the spatial heterogeneity of elk impacts on grasslands in areas that wolves frequently hunt. We also predict that this response should decrease browsing pressure on heavily-browsed woody plant stands in certain areas, which is supported by recent research in the GYE. This research highlights the importance of predator-prey behavioral interactions in large mammal systems.