Scholarship & Research
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/1
Browse
2 results
Search Results
Item Generalizing and transferring a GIS-based species distribution model: from one hot spot to another(Montana State University - Bozeman, College of Agriculture, 2018) Garcia Neto, Narciso; Chairperson, Graduate Committee: Clayton B. MarlowSpecies distribution models (SDMs) are efficient simulations of the distribution of species across geographical space and help to understand the spatial patterns of biological diversity. However, they are not designed to provide a description of species habitats. Geographic information systems (GIS) combined with SDMs have been used to illustrate the distribution and infer the sustainability and capability of habitats, to explore ecological relationships, serve as selection of vegetation types, avoidance of habitat disturbed by humans, establishing factors like predation, and to identify landscapes favorable for establishment of a new population. Despite the large number of SDMs papers published within the last decade, the practical utility of these models in the conservation management field remain sparse. The main objective of this research was to develop techniques for habitat modelling based on presence/availability data depicted by illustrative habitat maps and to test the new model on different landscapes. Resource selection function was used to develop a new model for the Yellowstone bison herd from published habitat maps. The predictor variables within the new model were elevation, ruggedness, profile curvature, percent of tree cove, Horizontal and vertical distance to water. The new model was then transferred and tested with field data from the National Bison Range and Grand Teton bison herds. The top predictive model performed better for the Yellowstone and Grand Teton herds than for National Bison Range herd. The output of this research indicated that habitat maps could work as source of land use by wildlife through transference to new areas of interest especially when local use data is not available.Item Applying predator-prey theory to evaluate large mammal dynamics : wolf predation in a newly-established multiple-prey system(Montana State University - Bozeman, College of Letters & Science, 2008) Becker, Matthew Smith; Chairperson, Graduate Committee: Robert A. Garrott; Patrick J. White (co-chair)I studied wolf prey selection and kill rates during 1996-97 through 2006-07 winters in a newly established two-prey system in central Yellowstone National Park. Prey differed substantially in their vulnerability to wolf (Canis lupus) predation and wolves preyed primarily on elk (Cervus elaphus) but also used bison (Bison bison) to varying degrees within and among winters and packs. Winter severity, wolf abundance, distribution, and prey selection varied during the study, concurrent with variations in the demography, distribution, and behavior of elk and bison. A total of 759 wolf-killed ungulates were detected and prey selection by wolves was influenced by the absolute and relative abundance of prey types, the abundance of predators, and the duration of snow pack. Wolves strongly preferred elk calves relative to all other prey types, and elk calf abundance was inversely related to the occurrence of bison in wolf diets. Increasing wolf numbers also broadened prey selection from elk calves, and predation on bison and adult elk increased with increasing snow pack accumulation and duration, likely due to its long-term debilitating influence. Elk abundance and wolf pack size best explained variation in kill rates for elk while bison calf abundance and snow pack duration best explained kill rates of bison. The functional response of wolves for elk was best described by a Type II ratio-dependent model, indicating significant predator dependence. Prey-switching evaluations indicated increasing selection of bison with increasing bison:elk ratios, however no concurrent decrease in elk predation occurred. Increased bison predation is not solely dependent on relative abundance of the two prey species; therefore it is unlikely at this time that wolf prey-switching will stabilize the system.