—Scott Stephens, Ph.D.
A drake pintail stands guard while its mate dabbles away to capture the abundant fairy shrimp in a shallow depression filled with snowmelt. The drake alerts the hen, and they flush as a young bison calf romps up to the wetland for a drink with its much larger mother close behind. As the pintails rise above the prairie, they see an endless expanse of unbroken grassland dotted with hundreds of gleaming wetlands.
For millennia, this was a scene that greeted breeding ducks as they returned to the Prairie Pothole Region (PPR) in spring. Sculpted by the massive forces of glaciation, this 300,000-square-mile area, named for millions of shallow "pothole" wetlands of varying sizes and depths, was once among the most expansive wetland systems in North America. Surrounding these wetlands were vast prairie grasslands subject to frequent disturbance by wildfires and great herds of grazing bison. Along the northern and eastern boundaries of the prairies and boreal forest, aspen parkland dominated the landscape. The combination of diverse and productive wetlands and abundant upland cover constituted the most productive ecosystem for breeding waterfowl on Earth. When snowmelt and spring rains filled prairie wetlands across this region, duck production was spectacular beyond belief, and the resulting fall waterfowl migrations blackened the sky. This remarkable productivity for breeding waterfowl gave rise to the region's nickname, "the Duck Factory."
Today, waterfowl find a much different ecosystem when they return to the prairies. Gone are free-roaming herds of bison, and in many areas seasonal wetlands have been drained and grasslands plowed under. As homesteaders settled the prairies, they soon discovered that the rich soil that once supported lush grassland, bison, and ducks could also raise bumper crops of grain. Extensive waterfowl habitat loss ensued across the Duck Factory, especially in eastern portions of the region where rich soils and a relatively wet climate are especially conducive for growing row crops. In Iowa and Minnesota, which at one time may have contained the most productive waterfowl breeding habitat on the prairies, more than 95 percent of historic wetlands and grasslands have been converted to other uses.
Fortunately for waterfowl and hunters, significant expanses of wetland-rich grasslands remain intact in parts of the Duck Factory. Landscapes with steep terrain and less fertile soils are not as intensively farmed because of the barriers to cultivation these factors present. Additionally, large blocks of native grassland managed for cattle grazing remain on the western prairies where a more arid climate produces less consistent crop yields.
Perhaps the most productive geographic area left for breeding waterfowl on the prairies is the Missouri Coteau, a narrow band of rolling hills that runs from southern South Dakota to southern Saskatchewan. Until recently, the coteau's rugged topography and light, rocky soils generally discouraged cultivation, leaving large tracts of native prairie surrounding mosaics of potholes. In especially wetland-rich areas of this region, breeding duck densities can exceed 120 pairs per square mile. For breeding ducks, the coteau and similar landscapes are bastions of high-quality habitat. For waterfowl hunters, these landscapes are vital to sustaining duck populations now and in the future.