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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.
Do spawning salmon indirectly influence ungulate space use in the Copper River Delta, Alaska by attracting bears?
(Montana State University - Bozeman, College of Letters & Science, 2020) DeFries, Elizabeth Shaw; Chairperson, Graduate Committee: Greg Francis
One of the key challenges in ecology is understanding the drivers of animal movements and distributions. Here, I used remote camera photography to examine whether the timing of spawning salmon altered ungulate space use due to the presence of bears. Using observational data collection methods, I quantified ungulate and bear presence at individual salmon spawning sites. I then analyzed relationships between bear and ungulate detection data to test for indirect effects between salmon and ungulates by applying linear regression models. A zero-inflated negative binomial model suggested that increases in bear detections are associated with decreases in ungulate detections. Results did reveal little overlap in the timing of ungulate and bear use of stream habitat during salmon spawning times, however, rigorous testing of my hypothesis may be limited by low rates of ungulate detection. Research dedicated to understanding the indirect effects of the timing of salmon spawning in the Copper River Delta can help evaluate the evidence for trophic interactions at various ecosystem levels. It may also offer insights into the potential magnitude the impact salmon has on the prey of large predators, other herbivore densities, plant communities, riparian area morphology, and essential ecosystem functions.
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.
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. Rotella
To 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.
Snowshoe hare habitat use and silvicultural influences in the Greater Yellowstone Ecosystem
(Montana State University - Bozeman, College of Agriculture, 2019) Kurzen, Mark Daniel; Chairperson, Graduate Committee: Bok Sowell
Snowshoe hares (Lepus americanus) are the main prey base of the Canada lynx (Lynx canadensis) and are an important food source for many forest carnivores. Snowshoe hare research in the Greater Yellowstone Ecosystem is lacking and current research conclusions differ in regards to the types and ages of forests that snowshoe hares prefer. The US Forest Service has implemented limitations and prohibitions on silviculture in this area based on previous snowshoe hare studies. However, some research in the Greater Yellowstone Ecosystem suggests that regenerating lodgepole pine (Pinus contorta) stands that are associated with silviculture benefit snowshoe hares. We implemented three snowshoe hare use indices in southwest Montana within a portion of the Custer-Gallatin National Forest during 1999-2012 to assess snowshoe hare use of forest cover types in Greater Yellowstone Ecosystem. Our study area was located in a designated US Forest Service timber management area where a history of silviculture has resulted in a heterogeneous landscape of multiple successional stages intermingled with other old growth stands. We analyzed 11 years of snowshoe hare pellet plot surveys using linear mixed models and AIC c model selection. Our results suggested that the understory conifer species was the best predictor of use and that the youngest two classes of regenerating lodgepole pine stands had the greatest snowshoe hare use. We analyzed 13 years of snowshoe hare track counts on roads within our study area using Chi-squared goodness-of-fit tests based on proportional road segment lengths and the associated cover types. We observed the greatest snowshoe hare habitat use in the youngest two classes of regenerating lodgepole pine stands. We live-trapped snowshoe hares for one winter in our study area and observed the greatest number of hares captured per night in the youngest lodgepole pine stands. The findings from our 13 year study suggest that snowshoe hare use was greatest in early successional lodgepole pine forests that were approximately 30-60 years old and associated with clear cutting and pre-commercial thinning.
Livestock depredation by grizzly bears on Forest Service grazing allotments in the Greater Yellowstone Ecosystem
(Montana State University - Bozeman, College of Agriculture, 2017) Wells, Smith Laura; Chairperson, Graduate Committee: Lance McNew
Grizzly bear population growth and range expansion over the last several decades in the Greater Yellowstone Ecosystem (GYE) has led to increased human-bear conflicts, including livestock depredation on public land grazing allotments. A better understanding of patterns and relationships between grazing allotment management and grizzly bear depredation of livestock is needed for adaptive, sustainable management in the ecosystem. Historic U.S. Forest Service and National Park Service livestock grazing records, grizzly bear habitat attributes, and documented livestock depredations by grizzly bears were collated for 316 public land grazing allotments within the grizzly bear Demographic Monitoring Area (DMA) during 1992-2014. Spatio-temporal relationships between annual livestock depredation counts and grazing allotment characteristics were modeled for each allotment during the study period at two spatial extents, representing daily and annual grizzly bear activity areas. As the Yellowstone grizzly population expanded during the last several decades, more public land grazing allotments were exposed to potential livestock-grizzly bear interactions and results indicated that both livestock stocking and grizzly bear habitat characteristics in and around allotments were related to documented depredations during 1992-2014. Annual numbers of livestock and grizzly bear density on allotments had a large, positive effect on average livestock depredation event counts. Allotment size and summer grazing both were related to higher depredation event counts while the presence of bulls and/or horses was related to lower counts. Allotments with less rugged terrain, lower road density, relatively higher vegetative primary productivity, greater amounts of whitebark pine, and further from forest edge on average were associated with higher average livestock depredation event counts. Managers and livestock producers could use these results to support adaptive management approaches and long-term planning such as increasing herd supervision, especially in areas with quality grizzly bear habitat and high grizzly bear density, or altering grazing management strategies and grazing locations to limit potential livestock depredation events. Results provide insight into historic livestock-grizzly bear conflicts on public lands in a large, complex ecosystem and although challenging, results could support cooperative management strategies to sustain the grizzly bear population and livestock operations in the GYE.
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 Willey
Most 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.
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. Zale
Non-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.
Effects of livestock grazing management on the ecology of grassland birds and their predators in a northern mixed-grass prairie ecosystem
(Montana State University - Bozeman, College of Agriculture, 2018) Vold, Skyler Thomas; Chairperson, Graduate Committee: Lance McNew; Lance B. McNew and Lorelle I. Berkeley were co-authors of the article, 'Effects of livestock grazing management on the ecology of grassland birds in a northern mixed-grass prairie ecosystem' submitted to the journal 'Rangeland ecology & management' which is contained within this thesis.; Lance B. McNew and Lorelle I. Berkeley were co-authors of the article, 'Effects of livestock grazing management on the occupancy of mesocarnivores in a northern mixed-grass prairie ecosystem' submitted to the journal 'The journal of wildlife management' which is contained within this thesis.
Grassland birds have recently undergone substantial population declines throughout much of their historic ranges in North America. The majority of remaining grassland bird habitat is rangeland managed for livestock production, so grazing management has implications for grassland bird conservation efforts. Populations of mesocarnivores have recently seen range expansions and increased abundance as a result of anthropogenic extirpation of apex predators in grassland ecosystems. Mesocarnivores are often major predators of grassland birds and their nests, so considering the effects of management actions on mesocarnivore occupancy is important within grassland bird conservation efforts. I evaluated the relative effects of three livestock grazing systems on grassland bird abundance and mesocarnivore occupancy in a northern mixed-grass prairie ecosystem of eastern Montana, USA. During 2016-17, I conducted replicated point-count surveys at 150 locations on a 3,000-ha ranch managed with rest-rotation cattle grazing, and 155 locations on adjacent reference properties (4,300-ha) employing season-long or 2-pasture summer-rotational grazing systems to identify grazing management influences on grassland bird abundances. During 2016-17, I deployed remote cameras at 45 locations within rest-rotation grazing systems, and at 45 locations on reference properties to identity grazing management influences on mesocarnivore occupancy. Overall, there was no noticeable benefit of rest-rotation grazing on abundance or species diversity of grassland birds relative to season-long and summer-rotation grazing systems. Species-specific responses to livestock grazing system were found for each of three obligate grassland birds. Support for interactions between grazing system and local rangeland production potential were found, limiting the ability to recommend general livestock management practices for the benefit of grassland bird populations. Additionally, abundance of grasshopper sparrow (Ammodramus savannarum; beta = -0.10 + or = 0.03) and western meadowlark (Sturnella neglecta; beta = -0.09 + or = 0.03) showed a negative relationship with increasing stocking rate. Occupancy of mesocarnivores was highest in rest-rotation grazing systems, followed by season-long and summer-rotation systems, respectively, and showed a positive relationship with increasing stocking rate (beta = 1.64 + or = 1.10). Regional guidelines for livestock grazing management may be inappropriate in terms of grassland bird conservation efforts in the northern mixed-grass prairie.
Natural enemy abundance and biological control in Bt maize using simulations of predator-prey interactions
(Montana State University - Bozeman, College of Agriculture, 2017) Brown, Christopher Regan; Chairperson, Graduate Committee: Robert K. D. Peterson; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and pests in maize to assess the influence of alternative food, cannibalism, and intraguild predation' which is contained within this thesis.; Laura A. Burkle, Daniel Salinas Duron, Adam Schapaugh, Christopher K. Sehy, Paul C. Stoy, David K. Weaver, Jeffrey D. Wolt and Robert K. D. Peterson were co-authors of the article, 'Simulating interactions between natural enemies and prey in Bt and conventional maize' which is contained within this thesis.
The potential effects of genetically modified maize expressing insect-resistant proteins from Bacillus thuringiensis (Bt) on natural enemies represent an active area of research highlighting considerable interest in understanding even subtle perturbations in agroecosystems. In the case of Bt maize, indirect effects on natural enemies may occur due to a reduced prey base caused by the desired effect of pest control by the Bt plant. Although these indirect effects may be subtle and difficult to study in the field, a modeling approach offers an alternative, allowing factors related to these subtle effects to be easily explored. In this effort, simulations of interactions between maize, two pests (the European corn borer (ECB) and an aphid), and two natural enemies (a lady beetle and green lacewing) were made using a modified TrophicLink model. TrophicLink is an individual-based model that uses functional ecology and food web network theory to simulate the trophic interactions of individuals and the resulting flow of energy. The individual-based model approach emphasizes the unique experiences of individuals and their trophic interactions leading to system level effects. Pollen utilization, cannibalism, and intraguild predation by natural enemies were simulated to explore the influence of these factors and to test the model. The model performed well in terms of reasonable representation of trophic functional types and interactions between them. The natural enemies were able to reduce a lepidopteran pest population and partially protect yield. The presence of pollen was influential in natural enemy population sizes and the biological control they provide. Cannibalism and intraguild predation caused notable reductions in natural enemy populations, but only small differences in biological control levels. In a second set of simulations involving Bt maize, prey-reduced scenarios included a short-term Bt maize scenario with ECB eggs and young larvae, and a second scenario without any ECB representing regional suppression of ECB by wide adoption of the Bt maize. Lady beetle and green lacewing population mass were similar across scenarios indicating resiliency of the generalist natural enemies to prey removal in the scenarios simulated. These findings are consistent with field study data that have not found consistent effects of Bt maize on natural enemies.

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