Thesis (M.A.)--Wisconsin. / Includes bibliographical references (leaves 80-81).

La détermination des facteurs influençant les décisions alimentaires des animaux est un thème central de l'écologie de l'approvisionnement et dans la compréhension des relations plante-herbivore. Mon objectif était de mieux comprendre l'effet de l'hétérogénéité à fine échelle spatiale sur le processus de décisions durant l'approvisionnement d'un grand herbivore grégaire, le bison des plaines (Bison bison bison). Pour cela, je me suis intéressée à trois niveaux de décisions : allocation du temps dans une parcelle, effort de recherche et choix de régime alimentaire. Mon chapitre 1 montre qu'une diminution de la disponibilité des plantes les plus profitables (ratio élevé entre contenu énergétique et temps de manipulation de la plante) sur l'aire du pré diminuait le temps de résidence des bisons, un effet atténué par une augmentation de la taille de groupe. Les bisons passaient aussi plus de temps dans le pré quand les stations alimentaires étaient relativement plus homogènes et riches en plantes profitables. Mon chapitre 2 met ensuite en évidence qu'en milieu naturel, l'efficacité avec laquelle les bisons trouvent les plantes de haute qualité diffère fortement entre les sexes et dépend de l'échelle spatiale considérée, de la répartition des congénères et de la saison. Les femelles adoptaient un comportement de recherche en accord avec les principes de maximisation des gains énergétiques et tiraient avantage de la présence de leurs congénères durant leur approvisionnement, contrairement aux mâles. Enfin, mon chapitre 3 montre que le risque d'herbivorie auquel font face les plantes dépend de l'agencement spatial des communautés végétales, notamment de leur proximité aux espèces les plus profitables pour le bison. À la station alimentaire, les bisons étaient capables de faire des choix alimentaires maximisant leurs gains énergétiques dans des assemblages végétaux complexes. En conclusion, ma thèse souligne l'importance du concept de maximisation des gains énergétiques pour le bison afin de prédire sa répartition dans leur environnement et son impact sur les communautés végétales. Mes travaux clarifient aussi l'importance des facteurs sociaux et environnementaux pour expliquer la dynamique d'approvisionnement de grands herbivores grégaires, et démontre que l'hétérogénéité de la végétation à fine échelle spatiale contrôle de façon importante leurs décisions alimentaires.

L’identification des facteurs qui déterminent les patrons de répartition et d’abondance des animaux est un sujet de recherche actuel et majeur en écologie. L’objectif général de ma thèse était de mieux comprendre comment un facteur en particulier, la prédation – prise au sens large pour inclure la chasse par les humains – influence les liens entre l’utilisation de l’espace et la dynamique des populations. Ma thèse explore les liens entre le risque de prédation, les déplacements et la sélection de l’habitat, le taux de mortalité et la viabilité d’une population vulnérable d’un grand herbivore. Le modèle d’étude a été la population de bisons des prairies (Bison bison bison) du parc national de Prince Albert, en Saskatchewan, soumise notamment à la prédation par le loup gris (Canis lupus) et à la chasse par les humains. Dans le chapitre 1, je mets en lumière les stratégies d’utilisation de l’espace des bisons face aux loups, et vice-versa, à l’aide d’analyses de déplacements et de sélection de l’habitat. De la deuxième moitié de l’été au début de l’hiver, les bisons réduisaient le temps passé sur des parcelles riches en nourriture suivant l’augmentation du niveau de fréquentation à long terme de ces parcelles par les loups. Les bisons quittaient également ces parcelles rapidement lorsqu’un loup était à proximité. En hiver, cependant, les bisons ne semblaient réagir qu’en s’éloignant lorsqu’un loup était à proximité. L’absence de réaction par les bisons au risque à long terme de rencontrer un loup en hiver pourrait s’expliquer sur une base énergétique : la nourriture est alors moins digestible et la neige rend leurs déplacements plus coûteux. Bien que le risque de prédation influence l’utilisation de l’espace des bisons, je démontre dans le chapitre 2 que la prédation par les loups, ainsi que des épisodes stochastiques de maladie (anthrax), ne représentent pas actuellement des dangers pour la viabilité de la population. À l’inverse, sous les conditions actuelles, la chasse par les autochtones – légale mais non réglementée – est la raison principale pour laquelle le risque d’extinction de la population atteint 66% sur les 50 prochaines années. Les bisons sont vulnérables à la chasse lorsqu’ils sortent du parc pour se nourrir sur des champs agricoles, attirés par une riche nourriture. Mes analyses précisent que chaque 1% de temps additionnel passé sur des champs avec permission de chasse de iii 2011 à 2016 augmentait le risque de mortalité par la chasse de 9%. Je révèle en outre que le temps passé sur ces champs devrait chuter de 70% pour que l’effectif actuel de la population se maintienne dans le temps suivant un scénario où la population est encore soumise à la prédation par les loups et à des épisodes d’anthrax. L’utilisation de seulement cinq champs agricoles comptait déjà pour plus de 70% de l’utilisation totale des champs avec permission de chasse par les bisons. Mettre en place des plans de gestion qui ciblent davantage ces cinq champs serait une stratégie efficace à court terme pour freiner le déclin de la population. Bien qu’une telle stratégie puisse mener les bisons à augmenter leur utilisation d’autres champs, l’impact démographique de la chasse devrait diminuer en conséquence, au moins à court terme, car cette activité est interdite dans la plupart des autres champs utilisés régulièrement par les bisons. Enfin, dans le chapitre 3, je compare, à l’aide d’un modèle basé sur l’individu, l’efficacité de différentes interventions de gestion manipulant la profitabilité (c.- à-d., le ratio entre quantité d’énergie digestible et temps de consommation) et la répartition de la nourriture pour réduire le temps que les bisons passent à l’extérieur du parc. Mes simulations suggèrent qu’assécher des prés à l’intérieur du parc pour y augmenter la disponibilité en nourriture naturelle serait peu efficace. Cependant, mes simulations suggèrent également que la mise en culture, à l’extérieur du parc, d’espèces végétales moins profitables pour les bisons que la nourriture disponible dans le parc serait une meilleure intervention. Cette thèse révèle d’abord le caractère dynamique et complexe des stratégies anti-prédatrices d’utilisation de l’espace d’un grand herbivore dans un système multi-proies. Ce travail met ensuite en lumière l’utilité pratique des différentes approches reliant l’utilisation de l’espace et la viabilité d’une population afin d’orienter la mise en place d’interventions de gestion plus efficaces. Le résultat final est une étude de cas approfondie visant à améliorer notre capacité à sauvegarder à court terme des populations vulnérables à des menaces reparties de façon hétérogène dans l’espace / Determining the factors that shape patterns of animal distribution and abundance is a major topic in contemporary ecological research. The overarching objective of my thesis was to better understand how one such factor, predation – in its broader meaning to include harvesting by humans – influences the links between space use and population dynamics. My work explores the links between predation risk, movement and habitat selection, mortality rates and the viability of a threatened population of large herbivore. The study system was the plains bison (Bison bison bison) population of Prince Albert National Park, Saskatchewan, subject most notably to predation by grey wolves (Canis lupus) and harvest by humans. In chapter 1, I use movement and habitat selection analyses to reveal the strategies of space use deployed by bison in response to wolves and vice-versa. From mid-summer to the onset of winter, bison reduced the time spent in patches rich in food as the long-term risk of encountering wolves there increased. Bison also left these patches more quickly when wolves were relatively close by. In winter, however, bison were observed to only react by moving away from nearby wolves. The absence of a bison response to the long-term risk of encountering wolves in winter could be explained by energetic constraints, as food is less digestible and movement more costly due to snow cover during this season. Although I reveal that perceived predation risk influences bison use of space, I show in chapter 2 that neither wolf predation nor disease (in the form of anthrax outbreaks) represent a threat to the viability of the population. Rather, the main reason behind a probability of population extinction of 66% over the next 50 years under current conditions is the legal, yet unregulated, harvest by native hunters. Bison are vulnerable to harvest when they leave the park to forage on rich food available in agricultural fields. My analyses refine our understanding of this pattern by showing that every additional 1% of time spent in fields with hunting permission from 2011 to 2016 increased the risk of harvest mortality by 9%. I also reveal that the time bison spend in such fields must drop by 70% for population abundance to remain stable at its current level in a scenario of continued wolf predation and anthrax outbreaks. More than 70% of bison use of fields with hunting permission were limited to just five fields. Management interventions targeting these riskier fields would be an effective short-term strategy to halt the population’s decline. Even though such an approach might lead bison to increase their use of other fields, the demographic impact of harvesting should consequently diminish, at least over the short term, given that harvesting is not permitted in most other fields used by bison. Finally, in chapter 3, I use an individual-based model to compare the relative effectiveness of different management interventions manipulating food profitability (i.e. the ratio between digestible energy and handling time) and distribution to reduce the time bison spend outside the park raiding crops and, thereby, the number of individuals harvested. My simulations suggest that draining meadows inside the park to increase the availability of natural forage there would not be very effective. However, my simulations also suggest that cultivating crops outside the park of lower profitability relative to natural forage inside the park would be a better intervention. My thesis reveals the dynamic and complex nature of the anti-predator movement and habitat selection strategies deployed by a large herbivore in a multi-prey system. My work also highlights the practical interest of linking spatial distribution to population viability to lead to more effective management interventions. The overall result is a thorough case study aimed at improving our ability, over the short term, to conserve populations vulnerable to threats which are distributed heterogeneously in space

Disease management along the boundaries of wildlife reserves is a growing conservation problem worldwide, as infected wildlife can migrate outside protected areas and pose a threat to livestock and human health. The bison Bison bison population in Yellowstone National Park has long been infected with Brucella abortus, the bacterium causing bovine brucellosis. Concern over migratory bison transmitting B. abortus to cattle herds on lands adjacent to Yellowstone has led to proposals for bison vaccination. Model simulations suggest that vaccination is unlikely to eradicate B. abortus from Yellowstone bison but could be an effective tool for reducing the level of infection and eliminating unpopular management practices such as lethal culling. The culling of Yellowstone bison to reduce the risk of brucellosis transmission to cattle is negatively affecting long-term bison conservation because of difficulties in diagnosing actively infected animals. Age-specific serology and B. abortus culture assays from slaughtered bison were used to develop a diagnostic tool to estimate whether particular animals are infective. Findings suggest that active B. abortus infection is age-dependent, which allows true infection probabilities to be estimated based on age and quantitative diagnostic tests. Active brucellosis infection was associated with below-average nutritional condition, with the intensity of B. abortus infection being influenced by seasonal reductions in dietary protein and energy. The reproductive strategy of Yellowstone bison is linked with the seasonal availability of food, which increases bison fitness but may have consequences for B. abortus infection. Seasonal food restriction may also influence the ability of vaccinated bison to recall protective immune responses when later exposed to B. abortus. The rate of fat metabolism was an important factor influencing cell-mediated responses. Thus, individual variation and the seasonal availability of food may reduce vaccine efficacy when vaccination is applied at the population level. Consequently, effective management practices will require a diverse range of integrated methods, which include maintaining separation of livestock and wildlife, managing habitat to reduce brucellosis transmission, and reducing disease prevalence in wildlife. The long-term success of these management practices will depend on sound science and support of the stakeholders involved.

This dissertation explores geographic and diachronic variation in Great Plains and Rocky Mountain Paleoindian (12,500-7000 14C years before present) forager exploitation of animal resources in order to explore how use of different habitats influenced land-use and subsistence strategies. To accomplish this goal, this study documented the full range of variability in the Paleoindian record using a combination of published data and new data. These patterns were then compared to explicit predictions derived from behavioral ecology and animal ethology and biology studies. The results, presented in this dissertation, allow the testing of several, often contradictory, important subsistence-settlement hypotheses in current Paleoindian research, specifically the ongoing debate about Paleoindian diet breadth and human causes of megafaunal extinction. Overall, there appears to be a covariance between environmental zone and forager land use. Paleoindian foragers structured their land use according to the presence and nature of a number of important resources within major environmental zones. Specifically, this study finds sites in grassland settings with low diversity of resources have lower artifact densities and are often dominated by exotic lithic raw materials. In these same areas prehistoric groups made almost exclusive use of large fauna. Sites in foothill/mountain or alluvial valley settings with ecologically high density and high diversity have higher proportions of short-term camps than do other areas and those camps have higher artifact density than do other types of sites. These sites exhibit a mixed use of small- and medium-sized game. Overall this study shows Paleoindian hunters had only modest impact on prey species.

Master of Science / Department of Biology / David C. Hartnett / A key feature of many grass-dominated ecosystems is the formation of grazing lawns, distinct patches characterized by intense grazing by mammalian herbivores and a dense short-statured grass canopy. A central concept of grazing lawns is the positive feedbacks between grazing animals and the grass resource. Intraspecific morphological plant trait changes and differences in plant species composition could both or individually play a role in the differences in characteristics of grazing lawns and neighboring tallgrass swards. I studied grazing lawns in North American tallgrass prairie to: a) test the ‘architectural shift hypothesis’ where continued grazing leads to changes in plant architecture resulting in more efficient foraging for grazers, creating a positive feedback that increases grazing and b) examine soil resource (nutrient and water) availability and grass nutritive quality on and off lawns to test the nutrient- and water-based pathways for grazing lawn maintenance. In a separate study (not reported here), we a) examined plant community structure on and off lawns to determine whether species composition differences account for the distinct grazing lawn characteristics and b) assessed effects of grazing lawn formation on tallgrass prairie plant species diversity. Several differences in morphological traits between dominant grasses on grazing lawns and tallgrass swards support the architectural shift hypothesis. For Sorghastrum nutans, Dichanthelium oligosanthes, and Pascopyrum smithii, leaf-to-stem ratio was twice as high on grazing lawns compared to surrounding matrix tallgrass vegetation and tiller branching was higher and culm internode lengths were shorter on grazing lawns for these species. However, Andropogon gerardii traits did not differ between grazing lawns and tallgrass vegetation. For all four species, above-ground tiller biomass and number of below-ground buds were both higher on grazing lawns. Overall, these morphological responses resulted in a higher grass canopy density (forage biomass per unit canopy volume) on grazing lawns and this increased grass canopy density in turn results in higher grazer foraging efficiency by increasing the amount of forage intake per bite and per unit time. D. oligosanthes, P. smithii, and S. nutans plants on grazing lawns had a significantly lower carbon-to-nitrogen ratio and higher nitrogen content than plants in the matrix tallgrass vegetation, while A. gerardii showed no significant difference in nitrogen content or in carbon-to-nitrogen ratio between grazing lawns and surrounding matrix tallgrass vegetation. With regards to the total grass canopy (all grass species combined), nitrogen content was significantly higher on grazing lawns compared to tallgrass vegetation for all three field seasons, 2016, 2017, and 2018. All measured soil nutrients, ammonium, nitrate, phosphorus, and sodium, were significantly higher on grazing lawns compared to soils of surrounding tallgrass swards, while water content showed no significant difference between grazing lawns and surrounding tallgrass vegetation. The results of this study strongly indicate that developmental and morphological shifts result in increased forage density and increased grazing efficiency on grazing lawns and that the frequent and intense activities of large grazers result in increased plant nitrogen content and lower C:N ratios in grasses on tallgrass prairie grazing lawns. Thus, at least two different mechanisms, plant architectural shifts and the nutrient-based pathway could both contribute to the positive feedbacks that encourage further grazing on lawns and grazing lawn maintenance on tallgrass prairie.

Lack of calibrated instruments and written records prior to European contact in North America has forced palaeoclimatic researchers to develop various proxies capable of reconstructing ancient environments. Stable isotope analysis of tooth enamel of large terrestrial herbivores has increasingly become a creditable method of determining the ancient environments which these large mammals occupied during life. Archaeological evidence indicates human inhabitants of the northern Great Plains relied heavily on bison procurement throughout much of the Holocene. Because of this correlation, stable isotope analysis of bison tooth enamel has the capability of informing on palaeoenvironmental conditions which these ancient cultural groups occupied for the last 10,000 years on the northern Great Plains. Decades of research has provided evidence that stable isotope analysis of tooth enamel of large bodied herbivores (e.g. bovids) has the potential to be used as a proxy for reconstructing palaeoclimate, palaeoecology, foraging strategies and herd behaviour. Oxygen (δ 18O) isotope ratios are used as a proxy to track the meteoric hydraulic cycle (i.e. precipitation), which in turn is driven by local surface temperatures. Carbon (δ13C) isotope ratios have the ability to indicate photosynthetic pathways used by plant species, thus indicating local terrestrial plant cover. Dietary intake of water (δ 18O) and food (δ13C) are associated with isotopic signals which are recorded in the tooth enamel of a bison during amelogenesis (tooth enamel formation). Once tooth enamel is formed it never remodels; therefore, isotopic ratios recovered from fossil enamel become an archive of dietary consumption. In general, δ 18O isotope ratios are used to determine surface water and surface temperature conditions, whereas δ13C isotope values are used to indicate the abundance of C3 to C4 grasses consumed during an animal’s life. This study analyzes stable isotope (δ 18O and δ13C) ratios obtained from fossil bison enamel associated with archaeological sites in the northern Great Plains (Saskatchewan) region. The purpose of this study is to create a comparative model used to indicate ancient seasonality and palaeoenvironmental conditions over a 9,000 year period in the Holocene. A total of eight archaeological sites were examined, with each site representing a distinct time period and an affiliated human culture. In addition, isotope (δ 18O and δ13C) ratios recovered from tooth enamel was compared to isotope (δD and δ13C) values previously (Leyden 2004) examined from bone collagen of bison remains from the same archaeological sites. Results of this study demonstrates that original isotopic values from consumed water (δ 18O) and food (δ13C) from archaeological bison tooth enamel reflects seasonal changes for an approximate 18 month period. Further, results from this study also indicate that several climate and plant ecology changes occurred in the Saskatoon, Saskatchewan region over the last 9,000 years. Episodes of climate warming and cooling have been inferred by changes in δ 18O ratios at different time periods of the Holocene. Similarly, significant differences are also detected in δ13C values from different archaeological sites, inferring that bison populations consumed various abundances of C4 grasses at different time periods. In addition, evidence from this study has indicated that stable isotope ratios from enamel (δ 18O) and collagen (δD) from the same archaeological site, for the purpose of inferring climate conditions, demonstrate differing data for several time periods and close correlations for others. On the contrary, δ13C from both tooth enamel and bone collagen from each archaeological site produce comparable data which were used to measure the abundance of C4 grasses consumed by bison population during particular time periods.

For this thesis our objectives were to establish an efficient method of ovarian synchronization and superstimulation in bison, and determine the effects of gonadotropin treatments on oocyte collection efficiency and quality in bison. In the first study we conducted two experiments to develop an efficient protocol for synchronization of follicular wave emergence during the anovulatory season. In Experiment 1, we compared the synchronizing effect of follicular ablation (n = 9) and treatment with 2 mg estradiol (E-) 17β in oil (n = 10), while in Experiment 2, we compared follicular ablation (n = 9) and treatment with 2 mg E-17β + 100 mg progesterone (P4; n = 10). Results showed that the degree of synchrony did not differ between ablation and hormone treatment groups in either Experiment, but follicular wave emergence was more synchronous in both treatment groups compared to the untreated control phase. The second study was conducted to develop an efficient method for ovarian superstimulation and oocyte collection during the anovulatory and ovulatory seasons. During the anovulatory season, one experiment was conducted in two replicates to compare the superstimulatory effect of 2500 IU of eCG (n = 10) given intramuscularly vs two doses of 200 mg of pFSH each (n = 10) given subcutaneously. Additionally, the effect of 25 mg of pLH given 24 hours prior oocyte collection on oocyte quality and collection rate was evaluated for each superstimulatory treatment. Results showed that treatment with pFSH induced a higher superstimulatory response and more cumulus oocyte complexes (COC) collected than did eCG during the anovulatory season. Furthermore, treatment with pLH increased the proportion of expanded COC that were collected with ultrasound-guided follicular aspiration. Two experiments were conducted during the ovulatory season, to develop an efficient protocol for superstimulation and oocyte collection. In Experiment 1, we compared the effect of two intramuscular doses of 200 mg of pFSH in saline (n = 11) vs two intramuscular doses of 200 mg of pFSH in a proprietary slow release formulation (SRF; n = 11). In Experiment 2, we compared the effect of a single dose of 2500 IU eCG intramuscularly vs two doses of 200 mg of pFSH administered subcutaneously. Results showed that a 2-dose regime of pFSH, diluted in either saline or a slow-release formulation induced a similar superstimulatory ovarian response in wood bison, while bison given a single-dose of 2500 IU eCG had a significantly lower ovarian response. In summary, synchronization of follicle wave emergence can be effectively accomplished in wood bison during the anovulatory season and follicular ablation, E-17β and E-17β + P4 treatments all shortened, and decreased the variability in the interval to follicular wave emergence. In addition, oocyte collection by transvaginal ultrasound-guided follicle aspiration from superstimulated bison was feasible and practical. Finally, treatment with pFSH was more effective than eCG to induce ovarian superstimulation for ultrasound-guided follicle aspiration in wood bison during both the anovulatory and ovulatory seasons.

For this thesis our objectives were to establish an efficient method of ovarian synchronization and superstimulation in bison, and determine the effects of gonadotropin treatments on oocyte collection efficiency and quality in bison. In the first study we conducted two experiments to develop an efficient protocol for synchronization of follicular wave emergence during the anovulatory season. In Experiment 1, we compared the synchronizing effect of follicular ablation (n = 9) and treatment with 2 mg estradiol (E-) 17β in oil (n = 10), while in Experiment 2, we compared follicular ablation (n = 9) and treatment with 2 mg E-17β + 100 mg progesterone (P4; n = 10). Results showed that the degree of synchrony did not differ between ablation and hormone treatment groups in either Experiment, but follicular wave emergence was more synchronous in both treatment groups compared to the untreated control phase. The second study was conducted to develop an efficient method for ovarian superstimulation and oocyte collection during the anovulatory and ovulatory seasons. During the anovulatory season, one experiment was conducted in two replicates to compare the superstimulatory effect of 2500 IU of eCG (n = 10) given intramuscularly vs two doses of 200 mg of pFSH each (n = 10) given subcutaneously. Additionally, the effect of 25 mg of pLH given 24 hours prior oocyte collection on oocyte quality and collection rate was evaluated for each superstimulatory treatment. Results showed that treatment with pFSH induced a higher superstimulatory response and more cumulus oocyte complexes (COC) collected than did eCG during the anovulatory season. Furthermore, treatment with pLH increased the proportion of expanded COC that were collected with ultrasound-guided follicular aspiration. Two experiments were conducted during the ovulatory season, to develop an efficient protocol for superstimulation and oocyte collection. In Experiment 1, we compared the effect of two intramuscular doses of 200 mg of pFSH in saline (n = 11) vs two intramuscular doses of 200 mg of pFSH in a proprietary slow release formulation (SRF; n = 11). In Experiment 2, we compared the effect of a single dose of 2500 IU eCG intramuscularly vs two doses of 200 mg of pFSH administered subcutaneously. Results showed that a 2-dose regime of pFSH, diluted in either saline or a slow-release formulation induced a similar superstimulatory ovarian response in wood bison, while bison given a single-dose of 2500 IU eCG had a significantly lower ovarian response. In summary, synchronization of follicle wave emergence can be effectively accomplished in wood bison during the anovulatory season and follicular ablation, E-17β and E-17β + P4 treatments all shortened, and decreased the variability in the interval to follicular wave emergence. In addition, oocyte collection by transvaginal ultrasound-guided follicle aspiration from superstimulated bison was feasible and practical. Finally, treatment with pFSH was more effective than eCG to induce ovarian superstimulation for ultrasound-guided follicle aspiration in wood bison during both the anovulatory and ovulatory seasons.

Water and lipid-soluble meat flavour precursors are gradually formed post-mortem via biochemical reactions. Storage time and temperature can affect final flavour precursor concentrations which in turn will affect the sensory quality of cooked meat. Selected key flavour precursors were monitored in Bison bison longissimus dorsi muscles from six animals stored at 2, 4, 8, 15 and 21 days at 4°C, in order to evaluate the effect of post-mortem conditioning on the formation of flavour precursors. Results were correlated with sensory data obtained using quantitative descriptive analysis with 8 trained panelists. While lipid-soluble flavour precursors remained mostly unchanged, significant increases (P<0.05) in concentrations of water-soluble flavour precursors including reducing sugars (eg. ribose, xylose), free amino acids (eg. valine, leucine) and adenosine-5’-triphosphate (ATP) degradation products (eg. inosine and hypoxanthine) were obtained with chilled storage conditioning post-mortem. The overall balance and correlations of water-soluble flavour precursors with storage day 15 and 21 were reported and can potentially impact the eating quality of cooked bison meat.