Global Warming and the Prairie Potholes

Sweeping across five Midwestern states (North Dakota, South Dakota, Iowa, Minnesota, and Montana) and four Canadian provinces, America's prairie potholes occupy 64million acres of what was once the heart of the Great Plains of North America.

Millions of shallow depressions were left as the ancient glaciers retreated. These round (like a 'pot') depressions are often filled with water, especially in wetter years, creating valuable wetlands. While some of these potholes never dry up, during times of drought the number of potholes with water declines dramatically.

Waterfowl breeding here include pintail, gadwall, blue-winged teal, green-winged teal, shovelers, canvasbacks and redheads and wigeon. Many other birds also depend on the potholes, such as the marbled godwit, bobolink, short-eared owls, Wilson's phalarope, Baird's sparrow, Sprague's pipit, and the increasingly rare grasshopper sparrow.

Benefits for Humans and Wildlife

The prairie potholes are extremely important to the nation's waterfowl populations. Some 50 to 80 percent of North America's annual duck production comes from the prairie potholes. During migration ducks from this region disperse throughout the lower-48 states and Alaska, where they are highly sought after by waterfowl hunters and birdwatchers, serving as an important economic resource for local cities and towns.

Prairie potholes also serve as natural sponges that hold excess water, and recharge groundwater systems that supply water to farmlands and wells in the region. In addition, the potholes provide water and forage for livestock.

Threats from Global Warming

Left unaddressed, global warming may dramatically reduce the suitability of prairie potholes for waterfowl. As open water and soil moisture decrease with rising temperatures and more severe droughts, many prairie potholes are expected to dry up more frequently or sooner in the spring, thereby eliminating or reducing their suitability for breeding waterfowl. Drought conditions brought on by global warming could dry up as much as 90 percent of the region's remaining wetlands, leading to nearly a 60%decline in breeding waterfowl in the region, and declines in other wetlands species as well.

Compounding the impact of global warming is the fact that the prairie pothole region has already lost up to 70 percent of its original wetlands, mostly to agriculture, and the losses continue. Thus, conserving the remaining prairie potholes is all the more important to maintain waterfowl populations, but also to maintain both surface and groundwater availability for agricultural purposes, including grazing and crop irrigation.

Conservation Investments to Minimize Global Warming Impacts

Minimizing impacts of global warming will require programs to secure conservation easements and discourage further draining or plowing of the remaining pothole wetlands. This is important to ensure that during times of severe droughts from global warming, a sufficient number of potholes with water are left to sustain minimal waterfowl populations.

Further protection from global warming can be achieved by undertaking efforts to restore degraded, drained and destroyed prairie potholes across a broad expanse of this historic region. Studies have shown that the most suitable areas for waterfowl production vary from year to year within the prairie pothole region due to local climatic conditions.

Thus, conserving and restoring wetlands across a broad range is necessary so that as the region becomes dryer overall due to global warming, there will still always be some areas for waterfowl to breed.

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