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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 …

Effects Of Myxobolus Cerebralis On The Population Dynamics Of Kokanee In Porcupine Reservoir, Utah, Arthur E. Butts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study tracked the chronology and severity of Myxobolus cerebralis infection and related it to survival of age-0 kokanee to determine whether M. cerebralis represented a significant agent of morality in the population. Environmental conditions and losses to predation were identified and linked to age-0 kokanee survival to identify other sources of mortality in the population. We attempted to track survival of age-0 kokanee from the outmigration into the reservoir until the end of the first growing season in September of each year. The number of age-0 kokanee that entered the reservoir was calculated by obtaining estimates of total egg …