In the event such drakes do not play an essential role in species survival, an effort should be made to provide for their utilization. Before the supernumerary drakes are harvested we must determine if disparate sex ratios of the magnitude observed today are a result of natural evolutionary mechanisms that enhance the survival of the species or if they are largely an artifact of modern man's activities. Our North Dakota reference area is part of the Prairie Pothole Region of central North America, which includes the aspen parkland transition area to the north. Because of the large number of mallards nesting in the Prairie Pothole Region, factors that significantly affect mallards there are of consequence to the continental population. Our purpose in Part Three is to examine the changes in our North Dakota reference area since pristine times that relate to mallard sex ratios and to place them in perspective relative to the entire Prairie Pothole Region.
Emphasis is on factors affecting densities and distributions of mallards and of canids.
Finally, we conclude by employing the predictive model of Part Two to reconstruct probable mallard sex ratios during pristine times in that region.