The research of this study found that spring cattle grazing (Bos taurus) reduced gadwall (Anas strepera) and blue-winged teal (Anas discors) cover. Gadwall and blue-winged teal nest densities decreased substantially during the three consecutive years of spring grazing compared to the post-treatment years. This reduction may have been influenced not only by the loss in cover, but also by the presence of cattle during the two species' nest initiation period. Nest density was not reduced for mallards (Anas platyrhynchos), who's nesting season is earlier. Gadwall annual nest densities, along with vegetative visual obstruction increased in the years following spring grazing. Mallard and blue-winged teal nest densities decreased on spring grazed fields in post-treatment years compared to pre-treatment years. However, these changes were probably due to a reduction in available water in the wetland basins, rather than vegetational changes following grazing. One year after spring grazing ended, vegetative visual obstruction readings were comparable to those taken in the control fields. Since no difference was found among the treatments for total nest densities during treatment and post-treatment years, the authors conclude that the grazing treatments had no effect of the total number of waterfowl nests. Nest success did not differ among the treatments. However, in some years, the treatments used for this study were unfavorable for most species of upland-nesting waterfowl.
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