Date of Award

5-1989

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

The impact of mammalian predation on upland nesting waterfowl was studied in central- North Dakota during the summers of 1987 and 1988. Survival of artificial nests was examined in relation to nest density, vegetation cover, distance from roads, active predator dens, and other artificial nests in a plot. Survival of artificial nests was also compared between an area with predator control and one without predator control.

Artificial waterfowl nests located in high density plots had a significantly lower probability of survival than nests located in low density plots. Although there were significant differences in vegetation height and density between years, the probability of survival of nests in dense vs. sparse vegetative cover was the same. There was also no relationship between nest survival and distance to roads, active predator dens, or other artificial waterfowl nests. The probability of survival of nests located in the predator control plot was significantly greater than nests located in the plot without predator control for the first experimental trial but not the second.

Striped skunks (Mephitis mephitis) and red fox (Vulpes vulpes) were the 2 most important nest predators on artificial waterfowl nests. The majority of eggs depredated by both fox and skunk were missing (75% and 36%, respectively). Of the remaining 64% of remains found at destroyed nests attributed to skunks, crushed egg remains were the most common type found. Fox left only 25% of all depredated eggs at the nest, but again crushed eggs were prevalent. The majority of egg remains left by skunks were in or adjacent to the nest bowl, while most remains from foxes were found 0,5-2 m from the nest bowl. Although many researchers document nest predators from descriptions in the literature, conflicting reports for the same predator are often found. In this study, the type and location of egg remains attributable to fox and skunk overlapped approximately 30%.

As nesting habitat decreases, waterfowl are forced to nest in smaller suitable areas at increased densities. The results of this study show that nests at higher densities had a significantly lower probability of survival than nests at lower densities, regardless of nesting cover, or distance to roads, active predator dens, or other artificial nests.

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