Snowshoe hares (Lepus americanus) are a critically important prey species for Canada lynx (Lynx canadensis). Determination of snowshoe hare distribution and abundance is needed in western Wyoming for lynx conservation. We used linear regression to examine the correlations between snowshoe hare density, as determined by mark-recapture estimates, and fecal pellet plot counts on both uncleared and annually cleared plots on the Bridger-Teton National Forest, western Wyoming. We found significant correlations between hare density estimates and fecal pellet counts for both uncleared and annually cleared pellet counts; however the relationship was much stronger for annually cleared pellet counts. Adjusting the buffer size by omitting hard habitat edges (not used by hares) around the trapping grids improved correlations between hare density and fecal pellet counts further. We recommend pellet counts from annually cleared plots be used when precise estimates of snowshoe hare abundance are required. Though precision is sacrificed when using uncleared plots, they are useful as a coarse index of habitat use by hares. The derived regression equations should be used to identify foraging habitat for lynx in western Wyoming. In addition to snowshoe hares, in western Wyoming red squirrels (Tamiasciurus hudsonicus) and grouse (Bonasa umbellus and Dendragapus obscurus) are used by Canada lynx. Whether young forests or older multi-storied forests contain more snowshoe hares, red squirrels, and grouse in western Wyoming is currently unknown. We estimated snowshoe hare density, and indexed red squirrel and forest grouse abundance in 3 classes of 30-70-year-old lodgepole pine (Pinus contorta) and 4 classes of mature multi-storied forest with a spruce (Picea engelmannii)-fir (Abies lasiocarpa) component. We recorded landscape and forest structure characteristics to understand how these influence lynx prey abundance. Overall, snowshoe hares, red squirrels, and forest grouse were more abundant in multi-storied forests than young forests. Forest attributes that predicted prey abundance were often more prevalent in multi-storied forests. Results from this study suggest that multi-storied forests with a spruce-fir component were disproportionately important to snowshoe hares, red squirrels, and forest grouse in western Wyoming. Canada lynx conservation efforts should focus on maintaining, enhancing, and promoting multi-storied forests in this region.

Au Canada, Francisella tularensis, une bactérie zoonotique causant la tularémie, affecte principalement le lièvre d’Amérique, le rat musqué et le castor. Malgré les nombreuses études sur cette maladie, les connaissances sur l’écologie et les réservoirs naturels de la tularémie demeurent limitées. Une étude transversale a été réalisée afin d’estimer la prévalence d’infection par F. tularensis chez le lièvre d’Amérique, le rat musqué et le coyote dans quatre régions du Québec (Canada) et de décrire le risque d’infection d’après des caractéristiques individuelles (âge, sexe et état de chair) et environnementales. D’octobre 2012 à avril 2013, 345 lièvres d’Amérique, 411 rats musqués et 385 coyotes capturés par des trappeurs ont été échantillonnés. Les caractéristiques environnementales autour du site de capture ont été extraites de base de données géographiques. La séroprévalence (test de microagglutination) était de 2.9% chez les coyotes, 0.6% chez les lièvres et 0% chez les rats musqués. Tous les rats musqués et les lièvres étaient négatifs à une PCR en temps réel réalisée à partir d’un pool de foie, rein, rate et poumon; par contre, le type AI a été détecté dans les organes individuels des deux lièvres séropositifs. Des analyses de régression logistique exacte ont démontré que l’âge était un facteur de risque pour la séropositivité du coyote, ainsi que la proportion de forêts et la proportion de l’environnement considéré approprié pour le lièvre autour de la localisation de capture des coyotes. Les résultats de cette étude suggèrent la présence du cycle terrestre dans les régions étudiées. / In Canada, Francisella tularensis, the zoonotic bacterial agent of tularemia, affects mostly snowshoe hares, muskrats and beavers. Despite numerous studies, knowledge of its ecological occurrence and natural reservoirs is limited. A cross-sectional study was conducted to estimate the prevalence of F. tularensis in snowshoe hares, muskrats and coyotes in four regions of Québec, Canada, and to describe the risk of infection in relation to individual host (age, sex and body condition) and environmental characteristics. Between October 2012 and April 2013, 345 snowshoe hares, 411 muskrats and 385 coyotes were captured by trappers. Ecological characteristics of the location of capture were extracted from geographical databases. Prevalence of antibodies against F. tularensis (microagglutination test) was 2.9% in coyotes, 0.6% in hares and 0% in muskrats. F. tularensis DNA was not detected by real-time PCR in the pools of liver, kidney, lung and spleen from muskrats and hares but F. tularensis type AI was detected during testing of individual organs of two seropositive hares. Exact logistic regression analyses showed that age was a significant risk factor for seropositivity of coyotes, as were the proportion of forest and the proportion of area considered suitable for hares in the environment around the location of capture of the coyotes. The results of this study suggest the presence of the terrestrial cycle of F. tularensis in the regions studied.

Research Doctorate - Doctor of Philosophy (PhD) / The original contribution of this thesis is to demonstrate the use of a generalised and parsimonious approach to building individual-based computer models of ecological systems with the objective of advancing our mechanistic understanding of these systems. Two models are presented; the first, a model of predator-prey interaction, produces the expected non-linear dynamics and illustrates the importance of the timing of variable updating and individual variation for the persistence of the populations. This model is applied to two near-exclusive, cycling predator-prey systems, those of the Canadian lynx and snowshoe hare and the Fennoscandian mustelid predators and their microtine prey. The reproduction of the patterns found in the empirical data of these systems by the model suggests that the underlying mechanism of these predator-prey systems may be more simple than is suggested by other more complex models reported in the literature. The second model describes a system similar to that of a grazing herbivore in a two-dimensional space. The emergence of complex behaviour resulting from the use of space in the model, including metapopulation-like local extinction and re-population and the effects of corridors and edge qualities on the species are demonstrated. The inclusion of a graphical display of the two-dimensional space in the computer interface to the model reveals important details of system behaviour not evident in the population means, including herding behaviour. The latter is dependent on herbivore mobility and the re-growth of resources in an heterogeneous environment, and emerges in the absence of social behaviour. The problem of detecting herding behaviour automatically is addressed, including the development of qualitative and quantitative definitions of herding in the model.