Quantifying the edge effects associated with predator removal blocks on the nesting success of upland ducks in North Dakota
Master of Science (MS)
Renewable Natural Resources
Much evidence suggests that nest success is one of the key drivers of duck production. Accordingly, for the past thirty years, waterfowl managers have focused their efforts on increasing nest success. One way to increase nest success is through predator trapping. Previous studies have shown that predator trapping increases nest success on different sized trapped blocks. This study attempted to answer the question: does trapping affect nest success on areas directly adjacent to trapped block boundaries? I hypothesized that predator abundance outside trapped blocks would be reduced. I predicted that nest success would decline with distance from the boundary while predator abundance would increase with distance from the boundary. This study was conducted in the Drift Prairie section of the Prairie Pothole Region in northeast North Dakota during the summers of 2005 and 2006. A total of 3,231 nests were found inside of six trapped blocks and a total of 2,006 nests were found outside of five trapped blocks. Daily survival rates were estimated using Shaffer’s logistic-exposure model and then related to distance from the center (for inside) or distance from the edge (for outside) of a trapped block, trapped block, field within a trapped block, and all interactions. Model fit was assessed using Akaike’s information criteria as adjusted for small sample size. The most important variables for explaining variation in daily survival rates of nests, both inside and outside trapped blocks, were year, and field within a trapped block. Distance appeared to have a negligible effect on daily survival rates for nests inside and outside trapped blocks. Mean daily survival rates were higher inside trapped blocks. Trapping, therefore, did not appear to increase daily survival rates outside trapped blocks. Predator scent-stations were used in 2006 to obtain an index of predator activity. Distance from a trapped block edge did not affect visitation rates for any individual predator species or for all species combined, both inside and outside trapped blocks. There were, however, significantly higher visitation rates inside versus outside trapped blocks for raccoons and for all species combined.
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Kuhn, Margaret Jean, "Quantifying the edge effects associated with predator removal blocks on the nesting success of upland ducks in North Dakota" (2007). LSU Master's Theses. 752.
Frank C. Rohwer