Secrets to Success
Over the past 15 years, Ducks Unlimited has conducted extensive research to better understand the needs of breeding waterfowl on the prairies. Based on this work, DU has gained a wealth of valuable information on the landscape and habitat conditions that influence duck breeding pair densities and nesting success across the region. Among the most important landscape features required for duck production is a functioning wetland community. Without wetlands to attract and provide food resources for breeding hens, ducks won't even attempt to breed. Land use practices on uplands surrounding wetlands also have a significant impact on wetland integrity and function. The healthiest wetlands on the prairies are usually found amid large blocks of native grassland, which are typically managed for livestock grazing. Ranchers view wetlands as valuable assets because they provide water for cattle and a much needed source of high-quality forage and hay during dry times.
In contrast, on cultivated landscapes many landowners view wetlands as a liability. Because crops don't fare well in saturated soils, farmers are often motivated to drain shallow seasonal wetlands embedded in cropland. Even on landscapes where wetland basins remain intact, soil erosion from surrounding fields can significantly degrade wetland productivity. Research on invertebrate communities in prairie wetlands has found that only a few millimeters of sediment can suffocate many species of aquatic insects that provide essential food resources for nesting hens. Additionally, runoff from herbicides and pesticides can harm wetland plants and decrease aquatic insect populations.
Beyond these impacts, upland land use can also affect how successful breeding ducks are in hatching nests and raising broods. Recent research on nesting success on the prairies has confirmed that the amount of grassland surrounding wetlands is an important factor influencing duck nesting success. Significant variability exists from year to year, but breeding ducks generally have better nesting success on landscapes with extensive perennial grass cover than on more intensively cultivated landscapes. Interestingly, studies suggest this relationship may not hold true in the parklands where nesting hens appear to fare better in native aspen habitat than in grassland. The parklands have a diverse predator community including numerous avian species such as hawks, owls, and corvids (crows and magpies), and the overhead cover provided by stands of aspen trees may provide the best protection for nesting hens in this environment
The Vanishing Prairie
Unfortunately, vital waterfowl habitat is now being lost at a staggering rate across the prairies, even in rugged areas like the Missouri Coteau. Surging global demand for food and ethanol is encouraging cultivation of every available acre. In the U.S. portion of the Duck Factory, declining enrollment in the Conservation Reserve Program (CRP), a Farm Bill program that pays farmers to restore grassland on marginal cropland under 10- or 15-year contracts, has resulted in a significant loss of upland nesting cover in many areas. During the past three years alone, more than 1.9 million acres of former CRP land have expired, and most of this upland cover has been converted back to cropland. Another 2.8 million acres of CRP could be lost in the next three years as more contracts expire. Even worse for the future of waterfowl, however, is the ongoing loss of native prairie, which represents the most abundant nesting habitat for waterfowl in the Prairie Pothole Region. Sadly, North Dakota, South Dakota, and Montana have lost more than 60,000 acres of native prairie each year since 2002. If current loss trends continue, maintaining recent duck population levels may be impossible.
Prairie wetlands are also at grave risk. In the United States, recent Supreme Court rulings have eliminated Clean Water Act protections for geographically isolated wetlands, leaving millions of small prairie potholes vulnerable to conversion. Presently, the Swampbuster provision of the Farm Bill, which prevents landowners who drain wetlands from receiving agricultural subsidies, is the last line of defense against wholesale wetland loss on the U.S. prairies and in many other regions. Wetland loss also remains the greatest threat to waterfowl in Prairie Canada, where few disincentives for wetland drainage are in place. And new threats such as wind power development could have unforeseen impacts on prairie waterfowl (see sidebar).
The stakes for waterfowl hunters couldn't be higher. About half of the average total annual production of ducks comes from the prairies. In addition, the U.S. Fish and Wildlife Service (USFWS) bases waterfowl season lengths and daily bag limits largely on the population status of breeding mallards and the number of ponds surveyed in Prairie Canada. As a result, reductions in midcontinent mallard populations of even 25 percent could result in shorter seasons and smaller daily bag limits in the Mississippi and Central flyways.