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Victoria J Dreitz

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In this thesis I explore a derivation of the MSAM using the DDO survey method to create a multispecies dependent double-observer abundance (MDAM) model. I use this tool to explore how two widely used grazing systems affect the abundance of eight songbird species with varying reliance on grassland vegetation in a sagebrush ecosystem.
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Estimating species abundance is important for land managers, especially for monitoringconservation efforts. The two main survey methods for estimating avian abundance are point counts and transects. Previous comparisons of these two methods have either been limited to a single species or have not included detection probability. During the 2012 breeding season, we compared and assessed the efficiency (precision for amount of effort) of point count time of detection (PCTD) and dependent double-observer transect (TRMO) methods based on detection probabilities and abundance estimates of five species of songbirds that use a range of habitats in a prairie system in Montana dominated by sagebrush and grassland vegetation....
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Assessing land use practices on ecological charateristics of sagebrush ecosystems
Livestock grazing practices are managed by private landowners and federal and state agencies across the western U.S. Increasingly, grazing strategies by these entities are incorporating conservation objectives and developing goals that include livestock production that is compatible with wildlife conservation objectives. This project evaluates the impact of conservation-oriented, rest-rotation livestock grazing and climate changes on migratory bird species associated with sagebrush habitat to better inform grazing management practices. Rest-rotation grazing management is likely to enhance important components of sagebrush, shrubland, and grassland habitat for a wide range of species, but little work has been done...
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Conservation of biological communities requires accurate estimates of abundance for multiple species. Recent advances in estimating abundance of multiple species, such as Bayesian multispecies N-mixture models, account for multiple sources of variation, including detection error. However, false-positiveerrors (misidentification or double counts), which are prevalent in multispecies data sets, remain largely unaddressed. The dependent-double observer (DDO) method is an emerging method that both accounts for detection error and is suggested to reduce the occurrence of false positives because it relies on two observers working collaboratively to identify individuals. To date, the DDO method has not been combined with...
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Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and...
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