Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xv, 188 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 134-137).

Peatlands provide a variety of ecosystem services including carbon sequestration, nutrient cycling and increased biodiversity, and are thus an important Canadian natural resource. Mountain peatlands, including those in the foothill region of the Canadian Rockies are particularly important due to their proximity to headwater streams which supply the Prairie Provinces with water. Yet, distribution of peatlands in the Canadian Rocky Mountains is unknown. There is also a lack of understanding of the form of these peatlands and the processes influencing them. The purpose of this research is to improve our understanding of Canadian mountain peatlands in terms of their abundance, distribution and subsurface form. Specific objectives are to: determine the distribution of beaver impacted wetlands in the study area; quantify the proportion of these which are peatlands; determine the impact beaver have on one hydrological variable, the area of open water and; describe the stratigraphy of peatlands with beaver at their surface. Beaver impacted wetland distribution was assessed through manual analysis of georeferenced aerial photographs. Combining these data with an existing GIS layer provided the basis of a wetland inventory of the region, allowing wetlands to be separately inventoried by physiographic location (Mountain and Foothills) and jurisdiction (Alberta Parks, Municipal Districts, Improvement Districts and First Nations Reserve). Approximately 75% of wetlands are located in the Foothills and Municipal District areas. Beaver impact is evident in 30% of the 529 wetlands inventoried, with the highest number in protected areas. Area of open water on wetlands, as assessed by manual analysis of aerial photographs, indicated that beaver impacted sites have on average approximately ten times more open surface water area than non- beaver impacted sites. In total, 81 wetlands were ground-truthed of which 77% were peat-forming wetlands or peatlands. Ground penetrating radar surveys and soil coring performed at 9 peatlands with beaver activity at their surface showed structural differences from those peatlands for which ecosystem services are described in the literature in that they are stratigraphically complex. Little is known about the factors affecting how this form develops, and this requires further study. The distribution of peatlands in the study area highlights them as important landscape units, and that in order to best manage them, further research is required into the various influences on their hydrological and ecological function.

Thesis (D. Min.)--Trinity International University, 2005. / Abstract. Includes bibliographical references (leaves 193-197).

Thesis (Ph.D.)--Ohio University, June, 2007. / Includes bibliographical references (leave 33)

Thesis (M.S.)--Brigham Young University. Dept. of Geography, 2007. / Includes bibliographical references (p. 79-87).

Thesis (D. Min.)--Trinity International University, 2005. / Abstract. Includes bibliographical references (leaves 193-197).

<p>The introduction of the North American beaver (Castor canadensis) to Tierra del Fuego is a widely known example of a successful biological invasion. Beavers have impacted enormously the biodiversity of the island of Tierra del Fuego, and they are now spreading northward on the continent, prompting the governments of Argentina and Chile to seek methods to control their spread. Beavers first established in forests, where they were initially introduced, but by the 1990s they began to establish in the adjacent steppe. In this dissertation, I study the biology of invasive beavers across the two major habitat types in Patagonia and attempt to develop modeling tools that might be useful to manage their spread.</p><p>In chapter one I studied the history of the beaver introduction in Patagonia and provide evidence that the beaver introduction occurred as a single release event of 20 beavers from northern Manitoba, Canada. This not only clarifies the origin of the invasion, but also suggests that the beaver population of Patagonia descends from a smaller number of individuals than previously assumed.</p><p>In chapter two I studied the demography of invasive North American beavers in the two contrasting habitat types of the island of Tierra del Fuego, forest and steppe. Habitat differences can affect vital rates which may in turn impact the speed of the invasion, but this has been rarely addressed when managing the spread of invaders. I use repeated observations, mark-resight methods, telemetry and camera traps to estimate colony size and vital rates of beavers in the two habitats. Colony size and the number of offspring (“kits”) produced per colony per year were higher in the steppe, contrary to the belief that forest is better habitat. Here I suggest this may be the result of the longer time since invasion in the forests of Tierra del Fuego and that the forest subpopulation is showing density dependent regulation. Beaver survival was high in all age classes and was higher than survival rates recorded in North America. My work shows that beaver plasticity and predator release have likely facilitated the invasion in Patagonia. </p><p>In chapter three, I investigated the more recent invasion of beavers in an area of the Patagonian steppe. I utilized repeated high resolution satellite images to identify beaver ponds, and used them to study changes in beaver abundance and habitat use over time. The number of beaver ponds increased 85 % between 2005 and 2014. During this period, beavers changed their habitat selection pattern, presumably as a response to increased density. Beavers established on small watercourses in canyons first, but as more canyons became occupied over time, beavers moved to less preferred watercourses in plains and U-shaped valleys. Potential new beaver colonies established close to existing beaver ponds, suggesting proximity to a beaver pond is an important determinant of beaver colonization. Identifying habitat preferred by beavers in the steppe could help to increase early detection of the invader at the invasion front. This work highlights the importance of the use of high resolution remote sensing technologies to better understand and monitor biological invasions. </p><p>Finally, in chapter four, I built a spatially explicit individual-based model parameterized with data I collected in the field and use it to make management recommendations. Specifically I assessed the efficacy of a potential management strategy in which a “fire-break” (a zone beyond the current population front in which beavers are removed) perpendicular to the population front is instituted to attempt to prevent further northward spread of the beaver in continental Patagonia. I found that even a 100 km wide firebreak is insufficient to contain the spread of beavers, long dispersal events being the major cause of this failure. Further, I found that increasing the fraction of beavers culled within the firebreak does not decrease either the arrival time or the number of beavers that cross the firebreak. Counterintuitively, my model indicates that moderate levels of culling within the firebreak (rather than high) may be a more effective method to manage the invasion, likely as a result of inversely density dependent dispersal.</p> / Dissertation

MHC glycoproteins are an essential part of adaptive immunity and may also play a role in mate choice. In addition, MHC genes are the most variable of all known genes. For these reasons, they have been intensively studied for several last decades. However, research is complicated due to extreme variability and frequent duplications. The Eurasian beaver seems to serve as an interesting model. It underwent a dramatic bottleneck culminating in the end of 19th century, when only about 1,200 individuals survived in several isolated relic populations. Thanks to numerous reintroductions, beavers of various origin meet in newly established populations. However, knowledge of beaver MHC was very limited. Only a single MHC gene has been investigated in a detail, and some relic populations were not sampled. Utilising additional relic populations and additional MHC locus, I verified a significant reduction of the variability of beaver MHC genes and also found signs of selection in the past. Then I sequenced MHC loci in two newly formed populations. I confirmed the ongoing selection by the disruption of cytonuclear equilibrium and the advantage of divergent alleles. We therefore can have a unique insight into the several periods of the history of beaver populations: In the past, MHC diversity was shaped by a...

Master's thesis deals with water utilization in exposition of arctic wolf and canadian beaver in ZOO Brno. Theoretical part describes water utilization in ZOO and processes in water connected with nutrient enriching and uprising of water bloom. Practical part focuses on monitoring water quality in April and May 2012 and concept to solute water filtration in ponds.

The presented thesis deals with the temporal and spatial changes in activity of the European beaver (Castor fiber L.) during different seasons. Basic dataset was obtained by continuous telemetric monitoring of selected individuals in years 2008 and 2009 in two different geographical areas, namely in the Bohemian forest and in southern Moravia. The scope of the thesis was to record, evaluate and interpret the behavior of European beaver during the year. I focused myself especially on the beginning and end of activity in relation to incidence of sunrise and sunset, duration of stay in the field, changes in the size of actively-used area and time-duration and length of the movement. In cases where there were more active individuals monitored within the studied area, I also watched for their mutual interaction. In statistical analysis of gained data I also took into account the sex and age of the individuals. Beaver's behavior varies during the year. They are most active in spring and autumn, while in winter their activity decreases significantly. This observation is valid not only for the time duration and length of movement trajectories, but also for the size of actively-used area. The beginning of activity is strongly correlated with the sunset, while the end does not show any correlation with...