Throughout midwestern North American ecosystems, semi-aquatic mammals including beaver (Castor canadensis), mink (Neovision vision), muskrat (Ondatra zibethicus), and river otter (Lontra canadensis) co-exist in wetlands. These species are ecologically important through their manipulation of habitats and interactions with other species present. The Lake County Forest Preserve District (Lake County, Illinois) is actively restoring forest preserves using several restoration practices and are interested in how these efforts may affect semi-aquatic mammal occupancy. We studied impacts of restoration practices and other environmental covariates on detection and occupancy of the 4 aforementioned focal species. Sign surveys were conducted during December-April in 2018-19 and 2019-20. Single species, multi-season models were run in RStudio using the package unmarked. Muskrat detection (p̂ = 0.60 ± 0.03) was positively affected by survey replicate, and negatively impacted by last precipitation amount and bank angle. Beaver detection (p̂ = 0.76 ± 0.03) was positively affected by survey replicate and previous 2-week precipitation amount, and negatively influenced by bank angle. Mink detection (p̂ = 0.26 ± 0.04) was positively impacted by survey replicate, and negatively affected by last precipitation amount and previous 2-week precipitation amount. River otter detection (p̂ = 0.10 ± 0.07) was not influenced by any covariates sampled. Muskrat had the highest occupancy (ψ ̂= 0.90 ± 0.05), followed by beaver (ψ ̂ = 0.57 ± 0.07), mink (ψ ̂ = 0.57 ± 0.10), and river otter (ψ ̂ = 0.28 ± 0.18). Both muskrat and river otter occupancy were not affected by any covariates sampled. Beaver occupancy was positively impacted by stream density and number of saplings. Mink occupancy was positively affected by stream density. No focal species’ occupancies were influenced by restoration practices. From these findings, I provide recommendations for future surveys and management for semi-aquatic furbearers in urban landscapes. Thank you to the Lake County Forest Preserve District for funding my research.

Movement is a core mechanism through which animals interact with their environment. A popular approach for investigating animal movement involves the use of GPS telemetry, which provides insights into both the spatial and temporal patterns exhibited by an individual or population. While many approaches for evaluating movement data have often analyzed intensity of use, most studies focused on a single property of use: the total duration an animal spent in a location. While this can provide insight into which landscape and habitat characteristics an individual may be selecting for, it does not fully account for how that space is being used. Therefore, it could be beneficial to combine more than one aspect of intensity of use to evaluate the behavioral mechanisms leading to patterns in space use, and by extension the drivers of home range structuring. As a territorial, central-place forager, the North American beaver (Castor canadensis) presents an ideal system for investigating drivers of home range structuring. However, while some species are easily tracked through traditional GPS attachment methods (such as GPS collars or backpacks), other species such as beavers present unique challenges given their fusiform shape and tapered neck. The overall objective of my thesis was to better understand fine-scale movement of beavers and the drivers of home range structuring. To do so, in chapter 1, I first developed and tested three different GPS transmitter attachment methods to determine which was most effective in terms of retention time (RT, total number of days a transmitter remains attached) and GPS fix success rate (FSR, % of successful fixes vs. attempted) and investigated to what degree various factors (season, sex, and age class) affected these results. In chapter 2, I analyzed space use in relation to four intensity of use metrics with machine learning to define homogenous types of space use. These metrics included the total number of visits, total and mean duration of visits, and mean interval between visits. GPS transmitters glued to the lower back of beavers provided up to two months of fine-scale data, as well as producing the highest FSR. In addition, longer retention times were found for transmitters attached to males versus females, and for transmitters deployed in the fall versus the spring. Using these data, I was able to capture five distinct population level intensity of use types including, low use – irregular, low use – regular, medium use – short duration, medium use – long duration, and lodge use. These types of use were all generally observed towards the core of the home range. In addition, all types of use were characterized by low intervals between visits except for the low use – irregular cluster. These results suggest highly structured, regular movements occurring in the core of beaver home ranges related primarily to shelter, foraging patches, and the movement paths used to link these locations. Overall, this approach allowed me to delineate between two distinct low use and medium use types and provided insight into the different behavioral mechanisms that may be driving these similar types of use. Capturing these different types of use was only possible by specifically combining multiple movement metrics at once to evaluate space use, as opposed to strictly using the number of GPS fixes to evaluate a location.

Mammals in freshwater aquatic systems play important roles as ecosystem engineers, trophic transfer agents, and apex predators, thus acting as indicators of freshwater ecosystem function. Watersheds inhabited by semi-aquatic mammals have increased links between adjacent terrestrial and aquatic ecosystems compared to watersheds where they are not present. Semi-aquatic mammals not only exert top-down influences on streams, but are affected by bottom-up forces from the riparian system itself. The goal of this study was to identify variables that correlate with the presence of beaver (Castor canadensis), muskrat (Ondatra zibethicus), mink (Neovison vison), and river otter (Lontra canadensis), including their interactions, resulting in a better understanding of the areas where these semi-aquatic mammals occur and their effects on the riparian system. The objectives of this study were (1) to identify variables related to the probability of detection, initial occupancy, colonization, and extinction of the 4 semi-aquatic mammals in southern Illinois; and (2) to test if the reintroduction of river otter has changed stream food webs. To address my first objective, I sampled 120 bridge sites in 2 periods (winter: Jan-Feb; and spring: Mar-Apr) during 2012–2014 in 11 major watersheds in the southern third of Illinois (44,526 km2) to estimate multi-season occupancy. Each survey unit was a 400-m stream segment visited twice by 2 observers for a total of 4 observations per site per period. Observers recorded all mammal signs found, including sign species and type. Sites were Intensive Basin Survey Sites sampled by Illinois Department of Natural Resources (IDNR) and Illinois Environmental Protection Agency (IEPA), allowing data collected by the state to be available for explanatory variables for mammal occupancy. Data collected by the Illinois Natural History Survey (INHS) also were available for a subset of sites. I collected local- and landscape-scale habitat and weather variables for each site. I developed hypotheses regarding occupancy of sites based on land-cover, human disturbance, and stream attributes for each species. I developed additional hypotheses regarding prey availability and water quality for river otter and mink. Sites used in each analysis were dependent on data available to address the hypotheses of interest. Beaver and muskrat were present at ≥100 of 103 sites for ≥1 observation. Naïve occupancy was high (≥82%) every year for both species. Detection probabilities for beaver and muskrat were best predicted by survey period. Beaver detection remained fairly constant across survey periods except for a decrease in winter 2014, whereas muskrat detection was generally lower during winter and higher during spring. Beaver were more likely to occupy larger streams than smaller streams during the initial survey period. Sites that lacked a dominant land-cover had a lower probability of beaver colonization than sites dominated by agriculture or woody vegetation at the landscape scale. In addition, the probability that a site would be colonized by beaver during the study increased with availability of water within 1 km of the surveyed segment, increased stream density, sites at larger streams, and river otter presence during the previous period. The probability of site extinction decreased as stream size, stream density within 1 km, and water availability within 500 m of the survey segment increased. Occupancy of muskrat during the initial survey period was negatively predicted by % forest in the 1-km riparian area, channel incision, and amount mercury in the sediment. Colonization by muskrats was lower during the long spring to winter intervals than the short winter to spring intervals, and was positively related to the amount of organic carbon in the sediment. The probability of site extinction by muskrat increased with increasing % forest within the riparian area around the stream segment, decreasing 1-km stream density, and when land-cover within 1 km of sites was dominated by agriculture or woody vegetation. Multi-season occupancy of river otter and mink were assessed in 2 separate analyses that used either land-cover and management variables or prey availability and riparian community composition, respectively. In the first analysis, river otter and mink were present at ≥84 of 103 sites. Naïve occupancy was higher every year for mink (≥88.3%) than for river otter (≥55.3%). Detection of river otter and mink in the first analysis increased as substrate availability increased. Occupancy of river otter during the initial survey period was predicted by large stream size, low % developed area within 250 m of the surveyed segment, and proximity to nearest river otter reintroduction point. Probability of colonization by river otter varied by survey period and was higher at sites with larger streams, higher stream density, lower % developed area, and within a known river otter population area. Site extinction by river otter in the first analysis varied by survey period and was linked to increased organic carbon in the sediment, and decreased road density within 1 km of the surveyed segment. River otter harvest was not found to affect site colonization or extinction. Mink occupancy during the initial period was negatively associated with water availability within 100 m of the survey segment. Site colonization by mink varied by month and increased with increasing developed area within 100 m of the surveyed segment, increasing channel incision, and decreasing rainfall. Probability of site extinction for mink increased as stream size and developed area within 500 m of the surveyed segment increased, and when woody vegetation was the dominant land-cover type within 1 km of the surveyed segment. The second analysis of multi-season occupancy of river otter and mink used 77 sites, 81.8% of which had ≥1 river otter detection in the study and 98.7% of which had ≥1 mink detection. Naïve occupancy differed between years but gradually increased for river otter and remained high (≥93.5%) for mink. Increasing substrate availability increased the probability of river otter detection, whereas mink detection varied by survey period. Occupancy during the initial survey period was higher in sites closer to the reintroduction points for river otter. Probability of colonization of river otter was positively associated with macroinvertebrate IBI and fish species richness, sites with high fish species richness of fish families preferred by river otter also had reduced otter extinction probability. No tested variables predicted initial occupancy for mink, but mink were more likely to colonize sites with increased fish richness and when muskrat were present during the previous period. Mink had decreased probability of extinction in sites with increasing mussel community index. My results indicate that semi-aquatic mammals in Illinois were affected by a riparian habitat, water availability, and stream community variables at both the landscape and local scale. I found high occupancy of mink, beaver, and muskrat across the entire landscape of southern Illinois, and my results suggest that the geographic range of river otter continues to expand. Relationships of occupancy of these semi-aquatic mammals to measurements of urban areas and human disturbance were not consistent across all species. Mink and river otter occupancy were both predicted by aspects of prey availability, indicating the importance of predator-prey relationships in occupancy dynamics of riparian predators. Hypotheses regarding predator pressure and changes in environmental variables were used to test the effects of river otter reintroduction on stream communities. For this objective, I used structural equation models. I compared fish and macroinvertebrate communities from before (1982-1995) and after (2005-2013) reintroduction of river otter, which occurred in 1994–1996. Fish and macroinvertebrate community data for 35 sites located throughout 6 major watersheds in southern Illinois (25,550 km2) were obtained from state agencies. Changes in stream communities were evaluated using 4 metrics (species richness, species dominance, skewness in size distribution of prey, and proportion of individuals in the size class preferred by river otter). Neither the inclusion of river otter site use nor change in stream quality, measured by change in % forest, improved models over the simple model which only included fish and macroinvertebrate communities. Overall, I found no evidence that river otter presence or change in forest cover affected stream fish and macroinvertebrate communities.

A sobre-exploração humana tem causado uma degradação generalizada e perturbação dos ecossistemas de água doce, os mais ameaçados do mundo. A bacia hidrográfica do Rio dos Sinos, no estado do Rio Grande do Sul, é considerada umas mais poluídas do Brasil. Seus cursos d’água estão sob diferentes graus de influência antrópica, bem como seus organismos dependentes. A lontra Neotropical é um mustelídeo semiaquático ameaçado por toda a sua área de distribuição continental onde há conhecimento. Embora a lontra seja um importante organismo para avaliar a qualidade ambiental por apresentar alguma tolerância a ambientes antropizados, pouco se sabe sobre seu status de conservação. Sua biologia, ecologia, comportamento e aspectos populacionais ainda são pouco conhecidos. Considerando isso, uma síntese de aspectos ecológicos e biológicos de Lontra longicaudis foi realizada através de extensa revisão bibliográfica. Além disso, avaliada a influência da qualidade da água em regiões com diferentes níveis de influência antrópica, bem como a estrutura da vegetação nas margens de rios, a sazonalidade e a velocidade da correnteza nos rios sobre a ocorrência de L. longicaudis. O componente experimental deste projeto foi realizado com base em amostragens mensais de material biológico não invasivo em 16 diferentes regiões da bacia do Rio dos Sinos no Rio Grande do Sul, ao longo de 2015. Ademais, foram realizadas entrevistas com moradores como método complementar para confirmar a presença da espécie. Nove novas áreas de registro de L. longicaudis foram confirmadas para o estado. A ocorrência de lontra foi modelada através de modelos lineares generalizados. Áreas com água de melhor qualidade (classes 2 e 3) apresentaram significativamente mais registros que áreas com água de qualidade inferior (classe 4). Adicionalmente, quer a correnteza, quer a época do ano também se mostraram relevantes para explicar os padrões de ocorrência da espécie. Em conclusão, a lontra Neotropical, assim como outros mamíferos semi-aquáticos poderão ser utilizados como bioindicadores de qualidade ambiental, especialmente em ambientes antropizados. No futuro, outras variáveis tais como a fisionomia e estágio de sucessão ecológica da vegetação das margens deverão ser considerados para explicar os padrões de ocorrência de lontra, no sentido de contribuir, de forma mais suportada, para a definição de medidas para a sua conservação. / Human overexploitation has caused the generalized degradation and disturbance of freshwater ecosystems, the most threatened in the world. The Sinos river basin in Rio Grande do Sul state is considered one of the most polluted in Brazil. Watercourses in this basin are under different degrees of anthropogenic influence, as well as all the organisms that depend on that water. The Neotropical otter is a semiaquatic mustelid threatened across its entire distribution area. While the otter is an important organism to evaluate environmental quality due to its intermediate tolerance to modified environments, little is known about its conservation status. Neotropical otter biology, ecology, behaviour and population aspects are still scarcely known. With this is mind, a synthesis of the ecological and biological aspects of Lontra longicaudis was done by means of literature revision. The effect of water quality in regions with distinct levels of anthropogenic influence, as well as vegetation structure, seasonality and flow velocity on otter occurrence was evaluated. The experimental component of this project was made based on monthly samplings of non-invasive biological material in 16 different regions of the Sinos river basin in Rio Grande do Sul in 2015. Moreover, interviews with local residents were made as a complementary method to confirm the species presence. Nine new areas of occurrence were detected in the state. Otter occurrence was modelled through generalized linear models. Areas with water of better quality (classes 2 and 3) presented significantly higher records than areas with water of lower quality (class 4). Additionally, both flow and season were also relevant in explaining the patterns of occurrence of the species. In conclusion, the Neotropical otter, as well as other semiaquatic mammals may be used as bioindicators of environmental quality, especially in human-altered environments. In the future, other parameters such as the physiognomy and the stage of ecological succession of the vegetation should be taken into consideration to explain patterns of otter occurrence, as a means to contribute, in a more sustained way, to the definition of conservation measures for the species.

A sobre-exploração humana tem causado uma degradação generalizada e perturbação dos ecossistemas de água doce, os mais ameaçados do mundo. A bacia hidrográfica do Rio dos Sinos, no estado do Rio Grande do Sul, é considerada umas mais poluídas do Brasil. Seus cursos d’água estão sob diferentes graus de influência antrópica, bem como seus organismos dependentes. A lontra Neotropical é um mustelídeo semiaquático ameaçado por toda a sua área de distribuição continental onde há conhecimento. Embora a lontra seja um importante organismo para avaliar a qualidade ambiental por apresentar alguma tolerância a ambientes antropizados, pouco se sabe sobre seu status de conservação. Sua biologia, ecologia, comportamento e aspectos populacionais ainda são pouco conhecidos. Considerando isso, uma síntese de aspectos ecológicos e biológicos de Lontra longicaudis foi realizada através de extensa revisão bibliográfica. Além disso, avaliada a influência da qualidade da água em regiões com diferentes níveis de influência antrópica, bem como a estrutura da vegetação nas margens de rios, a sazonalidade e a velocidade da correnteza nos rios sobre a ocorrência de L. longicaudis. O componente experimental deste projeto foi realizado com base em amostragens mensais de material biológico não invasivo em 16 diferentes regiões da bacia do Rio dos Sinos no Rio Grande do Sul, ao longo de 2015. Ademais, foram realizadas entrevistas com moradores como método complementar para confirmar a presença da espécie. Nove novas áreas de registro de L. longicaudis foram confirmadas para o estado. A ocorrência de lontra foi modelada através de modelos lineares generalizados. Áreas com água de melhor qualidade (classes 2 e 3) apresentaram significativamente mais registros que áreas com água de qualidade inferior (classe 4). Adicionalmente, quer a correnteza, quer a época do ano também se mostraram relevantes para explicar os padrões de ocorrência da espécie. Em conclusão, a lontra Neotropical, assim como outros mamíferos semi-aquáticos poderão ser utilizados como bioindicadores de qualidade ambiental, especialmente em ambientes antropizados. No futuro, outras variáveis tais como a fisionomia e estágio de sucessão ecológica da vegetação das margens deverão ser considerados para explicar os padrões de ocorrência de lontra, no sentido de contribuir, de forma mais suportada, para a definição de medidas para a sua conservação. / Human overexploitation has caused the generalized degradation and disturbance of freshwater ecosystems, the most threatened in the world. The Sinos river basin in Rio Grande do Sul state is considered one of the most polluted in Brazil. Watercourses in this basin are under different degrees of anthropogenic influence, as well as all the organisms that depend on that water. The Neotropical otter is a semiaquatic mustelid threatened across its entire distribution area. While the otter is an important organism to evaluate environmental quality due to its intermediate tolerance to modified environments, little is known about its conservation status. Neotropical otter biology, ecology, behaviour and population aspects are still scarcely known. With this is mind, a synthesis of the ecological and biological aspects of Lontra longicaudis was done by means of literature revision. The effect of water quality in regions with distinct levels of anthropogenic influence, as well as vegetation structure, seasonality and flow velocity on otter occurrence was evaluated. The experimental component of this project was made based on monthly samplings of non-invasive biological material in 16 different regions of the Sinos river basin in Rio Grande do Sul in 2015. Moreover, interviews with local residents were made as a complementary method to confirm the species presence. Nine new areas of occurrence were detected in the state. Otter occurrence was modelled through generalized linear models. Areas with water of better quality (classes 2 and 3) presented significantly higher records than areas with water of lower quality (class 4). Additionally, both flow and season were also relevant in explaining the patterns of occurrence of the species. In conclusion, the Neotropical otter, as well as other semiaquatic mammals may be used as bioindicators of environmental quality, especially in human-altered environments. In the future, other parameters such as the physiognomy and the stage of ecological succession of the vegetation should be taken into consideration to explain patterns of otter occurrence, as a means to contribute, in a more sustained way, to the definition of conservation measures for the species.

A sobre-exploração humana tem causado uma degradação generalizada e perturbação dos ecossistemas de água doce, os mais ameaçados do mundo. A bacia hidrográfica do Rio dos Sinos, no estado do Rio Grande do Sul, é considerada umas mais poluídas do Brasil. Seus cursos d’água estão sob diferentes graus de influência antrópica, bem como seus organismos dependentes. A lontra Neotropical é um mustelídeo semiaquático ameaçado por toda a sua área de distribuição continental onde há conhecimento. Embora a lontra seja um importante organismo para avaliar a qualidade ambiental por apresentar alguma tolerância a ambientes antropizados, pouco se sabe sobre seu status de conservação. Sua biologia, ecologia, comportamento e aspectos populacionais ainda são pouco conhecidos. Considerando isso, uma síntese de aspectos ecológicos e biológicos de Lontra longicaudis foi realizada através de extensa revisão bibliográfica. Além disso, avaliada a influência da qualidade da água em regiões com diferentes níveis de influência antrópica, bem como a estrutura da vegetação nas margens de rios, a sazonalidade e a velocidade da correnteza nos rios sobre a ocorrência de L. longicaudis. O componente experimental deste projeto foi realizado com base em amostragens mensais de material biológico não invasivo em 16 diferentes regiões da bacia do Rio dos Sinos no Rio Grande do Sul, ao longo de 2015. Ademais, foram realizadas entrevistas com moradores como método complementar para confirmar a presença da espécie. Nove novas áreas de registro de L. longicaudis foram confirmadas para o estado. A ocorrência de lontra foi modelada através de modelos lineares generalizados. Áreas com água de melhor qualidade (classes 2 e 3) apresentaram significativamente mais registros que áreas com água de qualidade inferior (classe 4). Adicionalmente, quer a correnteza, quer a época do ano também se mostraram relevantes para explicar os padrões de ocorrência da espécie. Em conclusão, a lontra Neotropical, assim como outros mamíferos semi-aquáticos poderão ser utilizados como bioindicadores de qualidade ambiental, especialmente em ambientes antropizados. No futuro, outras variáveis tais como a fisionomia e estágio de sucessão ecológica da vegetação das margens deverão ser considerados para explicar os padrões de ocorrência de lontra, no sentido de contribuir, de forma mais suportada, para a definição de medidas para a sua conservação. / Human overexploitation has caused the generalized degradation and disturbance of freshwater ecosystems, the most threatened in the world. The Sinos river basin in Rio Grande do Sul state is considered one of the most polluted in Brazil. Watercourses in this basin are under different degrees of anthropogenic influence, as well as all the organisms that depend on that water. The Neotropical otter is a semiaquatic mustelid threatened across its entire distribution area. While the otter is an important organism to evaluate environmental quality due to its intermediate tolerance to modified environments, little is known about its conservation status. Neotropical otter biology, ecology, behaviour and population aspects are still scarcely known. With this is mind, a synthesis of the ecological and biological aspects of Lontra longicaudis was done by means of literature revision. The effect of water quality in regions with distinct levels of anthropogenic influence, as well as vegetation structure, seasonality and flow velocity on otter occurrence was evaluated. The experimental component of this project was made based on monthly samplings of non-invasive biological material in 16 different regions of the Sinos river basin in Rio Grande do Sul in 2015. Moreover, interviews with local residents were made as a complementary method to confirm the species presence. Nine new areas of occurrence were detected in the state. Otter occurrence was modelled through generalized linear models. Areas with water of better quality (classes 2 and 3) presented significantly higher records than areas with water of lower quality (class 4). Additionally, both flow and season were also relevant in explaining the patterns of occurrence of the species. In conclusion, the Neotropical otter, as well as other semiaquatic mammals may be used as bioindicators of environmental quality, especially in human-altered environments. In the future, other parameters such as the physiognomy and the stage of ecological succession of the vegetation should be taken into consideration to explain patterns of otter occurrence, as a means to contribute, in a more sustained way, to the definition of conservation measures for the species.

The development and implementation of effective species and population-specific management strategies requires population-specific information. To demonstrate the relative extirpation risk associated with various road mortality scenarios for a population of Blanding’s turtles at Canadian Nuclear Laboratories in Chalk River, Ontario, a Population Viability Analysis was conducted. Road mortality of two adult females every ten years resulted in population extirpation within 200 years relative to a stable population not experiencing road mortality. To accommodate informed decision-making for the management of this species at risk, the movement patterns and habitat selection of this Blanding’s turtle population were described. There was no significant difference between males and females in distance moved between relocations in either the spring or the summer, but turtles moved greater distances in the spring than in the summer. Annual and seasonal home range size did not differ between the sexes or between spring and summer periods. A compositional analysis indicated Blanding’s turtles preferred marsh habitats over bog, swamp, lake, and upland. Matched-paired logistic regression was used to determine selection of microhabitat features, such as type of vegetation, in the spring and summer. Turtles preferred sites with warmer air temperatures, shallower water, a higher availability of open water, and greater coverage of emergent and floating vegetation types in the spring period. In the summer period, turtles preferred sites characterized by cooler, deeper water, a higher availability of open water, and greater coverage of emergent and floating vegetation types. This population of Blanding’s turtles appears to be relatively small and the continued threat of road mortality indicates a delicate situation for its persistence. Considering seasonally preferred habitats will best inform management decisions for seasonal work restrictions and future development plans.

Se déplacer dans l’eau ou sur terre implique de faire face à des contraintes mécaniques extrêmement différentes. L’eau est sensiblement plus dense et visqueuse que l’air et, par le fait, la locomotion aquatique est dominée par la traînée et la poussée d’Archimède alors que la locomotion terrestre est dominée par la gravité et l’inertie. Si les adaptations les plus extrêmes à la locomotion dans chacun de ces milieux sont bien documentées, les espèces semi-aquatiques qui se déplacent fréquemment dans ces deux milieux restent peu étudiées.Les mustélidés présentent une large diversité de spécialisations locomotrices tant du point de vue du type de milieu fréquenté que du point de vue du degré de spécialisation.Cela inclut trois événements indépendants d’apparition d’un mode de vie semi-aquatique avec pour représentants actuels : le vison d’Europe, le vison Américain et les loutres. En utilisant la morphométrie géométrique pour quantifier l’ensemble de la forme de l’humérus, du radius, de l’ulna, du fémur, du tibia et de la fibula, j’ai étudié les différences morphologiques de l’appareil locomoteur des mustélidés terrestres et semi-aquatiques. Étant donné que les visons et les loutres font face aux mêmes contraintes fonctionnelles liées à une locomotion à la fois terrestre et aquatique, j’ai testé si leur morphologie convergeait. Enfin, étant donné la différence de contraintes fonctionnelles induites par les deux milieux, j’ai testé si le milieu de locomotion avait un impact homogène sur l’appareil locomoteur ou si une spécialisation de certains os pouvait être observée.Si les visons diffèrent peu de leurs parents terrestres, les loutres montrent d’importantes différences en termes de taille, forme et proportions relatives des os. Les visons présentent une morphologie similaire à celle observée chez tous les Mustelinae.Néanmoins, la morphologie de l’humérus est convergente entre les deux visons, avec une courbure plus grande que chez leurs parents terrestres. La morphologie des visons résulte de spécialisations récentes de la morphologie versatile propre aux Mustelinae, leur mode de nage est similaire à celui des Mustelinae terrestres et ils ne montrent que de subtiles différenciations morphologiques.A l’opposé, les loutres présentent des os longs dont la forme diffère nettement de celle de leurs parents terrestres. De plus, elles montrent une grande diversité de formes, en opposition avec l’hypothèse qui voudrait que de fortes contraintes fonctionnelles, telles que celles induites par la locomotion aquatique, devraient conduire à un nombre limité de réponses évolutives possibles. Les loutres montrent un ensemble de caractéristiques morphologiques en lien avec la locomotion aquatique: des os robustes, avec de larges épiphyses, un stylopode court relativement au zeugopode et un grand bras de levier pour les extenseurs du coude. Seule la loutre de mer (Enhydra lutris) montre une spécialisation différente entre les pattes avant et arrière. Les pattes arrière sont dédiées à la locomotion aquatique avec un grand bras de levier pour les muscles de la hanche et un pied transformé en palette natatoire. La patte avant, en revanche, présente une ulna gracile, avec un processus olécrane court et un radius courbé cranialement, produisant un patronde co-variation unique. Ces particularités permettent de plus grands degrés de liberté dans les mouvements de l’avant-bras, et de fait, les capacités de manipulation uniques chez cette espèce.Ainsi les mustélidés semi-aquatiques présentent une diversité qui n’était pas attendue étant donné la différence de contraintes mécaniques imposées par la locomotion dans l’eau et sur terre. Les mustélidés semi-aquatiques semblent avoir évolué depuis une morphologie ancestrale versatile jusqu’à des formes très spécialisées,où la réduction progressive de la locomotion terrestre a permis une spécialisation différente entre les membres antérieurs et postérieurs. / Moving in water and on land implies coping with drastically different mechanicalconstraints. Water is substantially more dense and viscous than air and thus aquaticlocomotion is dominated by drag and buoyancy when terrestrial locomotion is dominatedby gravity and inertia. If extreme adaptations to locomotion in each of thesetwo media are well described, semi-aquatic species that move extensively in bothmedia remain poorly studied.Mustelids presents a large diversity of locomotor specializations involving differentkinds of locomotor environments and different degrees of specialization. It encompassthree independent evolutions of a semi-aquatic lifestyle: the European mink,the American mink, and the otters. Using geometric morphometrics to quantify theshape of the entire humerus, radius, ulna, femur, tibia, and fibula I investigated morphologicaldifferences in the locomotor apparatus of terrestrial and semi-aquaticmustelids. As both minks and otters face functional pressures resulting from bothaquatic and terrestrial locomotion, I tested whether their morphology converged.Finally, considering the differences in the functional requirements of the two media,I explored whether the locomotor ecology has a homogeneous impact on thelocomotor apparatus or whether a functional specialization of certain parts can beobserved.Whereas minks show low morphological differentiation from their terrestrial relatives,otters diverged a lot in both shape, size, and the relative proportions of thelimb bones. Minks present a morphology that is similar to the one observed in otherMustelinae. Nevertheless, the shape of the humerus is convergent between thetwo minks, and shows a greater curvature than in their terrestrial relatives. Minksresult from recent specializations of the versatile morphology of Mustelinae witha swimming mode similar to the one of the terrestrial Mustelinae and only subtlemodifications of their long bone morphology.Conversely, otters present a long bone shape that is strongly divergent from theone of their terrestrial relatives. Additionally, they show very diverse long boneshapes in opposition to the hypothesis stating that strong functional requirements,as the ones induced by aquatic locomotion, should induce a limited number of potentialevolutionary responses. Otters show morphological features that are related to aquatic locomotion: robust bones with broad epiphyses, a short stylopodrelative to the zeugopod, and a long in-lever for elbow extensors. Only the sea otter(Enhydra lutris) presents a functional specialization that differs between hind andforelimb. The hind limb is dedicated to aquatic locomotion with a strong in-lever forthe hip muscles, and the feet that are modified into swimming paddles. Meanwhile,the forelimb presents a relatively gracile ulna with a short olecranon process and aradius that is curved more cranially, resulting in a drastic change in the pattern ofco-variation. These features are interpreted as providing greater degrees of freedomin the movements of the forearm, which allows the unique manipulative skillsof this species.Thus semi-aquatic mustelids present a diversity that was not expected given thestrong differences in the mechanical constraints imposed during locomotion in waterversus on land. Semi-aquatic mustelids appear to have evolved from the versatileancestral locomotor apparatus to highly specialized forms, where the progressivereduction of terrestrial locomotion allowed differential adaptation of the foreandhind limbs.

<p>  </p> <p>Semi-aquatic mammals, such as American beavers (<em>Castor canadensis</em>), muskrats (<em>Ondatra zibethicus</em>), North American river otters (<em>Lontra canadensis</em>), and American mink (<em>Neogale</em> <em>vison</em>), often play important roles in their ecosystem. Beavers and muskrats can manipulate plant community structure through the use of woody debris and forbs. As mesocarnivores, North American river otters and American mink can also drive community structure through the predation. Traditionally, these species are monitored using sign surveys (i.e., walking transects and visually identifying scat, tracks, and latrines). Camera trapping has also been used to survey semi-aquatic species occupancy to a lesser extent. However, due to their almost exclusive use of edge habitat, they may be ideal species to camera trap. Another more recently employed survey method is environmental DNA (eDNA), which involves the extraction of DNA from environmental samples (such as soil, water, air, and snow) to determine species occupancy. In this study, I evaluate environmental DNA and camera trapping as survey methods for detecting semi-aquatic mammals around northeastern Indiana. In the first chapter, I used eDNA sampling and camera trapping to monitor seven sites for three weeks during March – May 2021 in order to determine the presence of American mink. I found that the naïve occupancy for each site was 0.86. Although the detection probability of eDNA was lower than that of camera trapping (0.25 and 0.36, respectively), the occupancy models created suggest that there was no difference in detection probability between the two methods. I also compared the cost and time spent per sample and found that both were 20% lower for eDNA than camera trapping. The results of my study suggest eDNA may be a cost- and time-effective method for surveying for American mink occupancy. The objective of my second chapter was to determine the number of camera traps required to obtain reliable data for detecting semi-aquatic mammals. A minimum requirement for number of camera traps would be useful knowledge for wildlife managers in terms of budgeting and resource management and could also help to refine current camera trapping methodologies. I camera trapped four ponds for four weeks during June – July 2021, varying the number of camera traps (1 – 5) used at each pond each week. I collected a total of 66,543 photos and detected one semi-aquatic mammal throughout the study period (<em>Neogale vison</em>). Due to the lack of semi-aquatic mammals detected, I could not perform any analyses.</p>