By Johann Walker, Ph.D., and Dave Howerter, Ph.D.
Small wetlands in the Prairie Pothole Region (PPR) of the United States and Canada are the lifeblood of North America's duck populations. Year after year these incredibly productive habitats provide abundant food and cover for millions of nesting hens and growing ducklings during vital stages of their life cycle, including egg formation, duckling growth to fledging, and the annual molt. Indeed, prairie wetlands produce and sustain a large portion of this continent's ducks from the time of spring snowmelt to freeze-up and the fall migration.
Small prairie wetlands provide ideal habitat for ducks throughout the breeding season. When spring arrives, shallow temporary and seasonal wetlands are the first to fill with runoff from melting snow and early rains. Their nutrient-rich hydric soils warm rapidly and create an ideal environment for the explosive growth of aquatic invertebrates such as insect larvae, snails, and freshwater shrimp, which provide the protein and calcium the nesting hens need to produce a clutch of eggs. As the breeding season progresses, growing ducklings and molting hens find abundant food resources in deeper seasonal and semipermanent wetlands. These wetlands also produce lush stands of emergent plants such as bulrush, which provide escape cover from predators. The combination of plentiful nutritious food resources and secure cover provided by prairie wetlands is the key to large fall flights of ducks, especially in the Central and Mississippi Flyways.
Waterfowl aren't the only beneficiaries of the bounty of resources provided by prairie wetlands. Science clearly shows that intact complexes of prairie wetlands store floodwater, reduce pollution in runoff and groundwater, store and sequester carbon, decrease erosion, and provide habitat for hundreds of plant and animal species. Despite their many benefits to waterfowl, other wildlife, and people, prairie wetlands are among the most imperiled ecosystems on earth. Widespread intensive drainage has been an ongoing problem on the prairies for more than 150 years, with devastating results. In Iowa, for example, more than 90 percent of historical prairie wetlands have been lost. Today, the state's prairie region supports fewer than 170,000 breeding duck pairs in a landscape that once supported 2 million pairs.
In the United States, the landscape encompassing prairie wetlands is 90 percent privately owned and largely used for crop production. Unfortunately, drainage continues—even on landscapes with very few remaining wetlands. A recent study by the U.S. Fish and Wildlife Service (USFWS) reported that Minnesota, which is one of the most intensively drained states in North America, lost a greater percentage of its remaining prairie wetlands than any other state in the PPR between 1997 and 2009. But wetland drainage and development doesn't stop at the international border. Up to 70 percent of wetlands in southern Canada have been lost, and wetland loss rates in Canada have remained steady for more than 30 years.
The ecological tragedy of prairie wetland loss is a complex problem. The prairies have been losing wetlands for several generations. In some areas, such as central North Dakota and parts of central Saskatchewan, more than 50 percent of historical wetlands remain, and watersheds and duck populations are strong. However, the rapidly changing global commodity market puts additional pressure on the remaining wetlands, and technological advances such as crop breeding for drought-resistant corn varieties allow farming to expand into areas where agriculture would not have previously been economically viable.
Ducks Unlimited's prairie conservation efforts are grounded in a strong scientific foundation, based on decades of research and data collected by biologists observing waterfowl on these landscapes. That information is used to create planning tools to estimate not only the negative impacts of wetland losses but also the positive effects that DU's conservation programs have on breeding ducks.
In addition, Ducks Unlimited Canada's Institute for Wetland and Waterfowl Research has invested heavily in quantifying the broader benefits that waterfowl habitats offer society, as well as the problems associated with wetland losses. For example, in one watershed in east-central Saskatchewan, wetland drainage over a 50-year period increased annual stream flows by 29 percent and peak flood levels by 32 percent. Further, it is estimated that wetland drainage on the Canadian prairies has released 43.5 million tons of carbon that was previously stored in wetland sediments and vegetation. Those emissions are equivalent to adding 33.5 million cars to our highways.
Ducks Unlimited's conservation programs are a long-standing staple of efforts to protect the PPR. DU staff work directly with private and public landowners throughout the region to conserve wetlands through land acquisition, conservation easements, and habitat restoration. In the Dakotas and Montana, for example, DU uses philanthropic gifts and funds from federal grants to purchase minimally restrictive wetland easements from willing sellers. These easements, which prohibit draining, filling, and burning of wetlands in perpetuity, are held by the USFWS. Similar easements held by DU Canada are a growing part of the organization's conservation efforts across the prairie provinces.
At the same time, DU recognizes the power of public policy to secure the future of prairie wetlands. For example, in the United States, wetland conservation provisions under the Farm Bill require farmers and ranchers to conserve wetlands in exchange for access to publicly funded crop insurance and conservation programs. This private-public partnership provides a measure of security for more than 2 million acres of prairie wetlands, including their value as waterfowl habitat and other values they provide. In Canada, where wetland protection regulations fall under provincial jurisdiction, DU Canada staff regularly use scientific evidence to inform public policy debates.
Without the millions of wetlands in the PPR, North America's duck population would be a small fraction of its current size. In addition to producing bountiful annual duck migrations, these small but mighty ecological powerhouses trap floodwaters, remove pollutants, store carbon, and reduce erosion. Ducks Unlimited is working tirelessly with our partners on both sides of the 49th parallel to ensure that prairie wetlands will continue to raise abundant populations of waterfowl and provide other ecological benefits for generations to come.
Dr. Johann Walker is director of conservation programs in DU's Great Plains Region and Dr. Dave Howerter is director of national conservation operations for DU Canada.