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Seasonal Movements Of Fluvial Bonneville Cutthroat Trout In The Thomas Fork Of The Bear River, Idaho-Wyoming, Warren Colyer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The majority of interior cutthroat trout (Oncorhynchus clarki) subspecies have been extirpated from large rivers by anthropogenic activities that have fragmented habitats and introduced non-native competitors. Selective pressures against migratory behaviors and mainstream river occupation and conservation schemes that isolate genetically pure populations above barriers have restricted gene flow and prevented the expression of fluvial life history traits in many populations. Existing knowledge about the movements and home range requirements of fluvial cutthroat trout is therefore limited. We implanted a total of 55 Bonneville cutthroat trout (BCT) in the Thomas Fork River, Idaho, with radio transmitters and located …

The Influence Of Predator Exclosures And Livestock Grazing On Duck Production At Bear River Migratory Bird Refuge, Utah, Benjamin C. West

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nest predation is a major factor impacting duck production and recruitment on breeding areas in North America. I surveyed waterfowl managers employed by the U.S. Fish and Wildlife Service and U.S. state wildlife agencies to determine their beliefs about nest predation and its management. Over 64% of respondents believed that rates of nest success on their management units averaged < 30% between 1996-2000. Managers believed habitat management and direct predator control were the most effective techniques to reduce nest predation. The construction of predator ex closures around nesting habitat also has been recommended to reduce nest predation. Between 1999-200 I, I evaluated the effectiveness of 4 predator ex closures to enhance duck nest success at Bear River Migratory Bird Refuge, Utah. During this period, rates of nest success in the exclosures were slightly higher than that within control plots, but still < 15%. Although published guidelines commonly recommend predator fences < 117 cm in height, I observed red foxes jump the 11 4-cm-high fences. Additional research is needed to identify effective predator fence designs.

Wildlife managers have argued that periodic disturbance of vegetation should be a component of management on waterfowl breeding areas. Although many techniques are available to manipulate vegetation, grazing by domestic livestock has been controversial. Some researchers have reported that livestock grazing …