By Scott Stephens, Ph.D.
Following one hen throughout its annual cycle reveals much about the key habitat challenges facing waterfowl
The rising sun peeks over the rolling hills of North Dakota’s Missouri Coteau, gradually warming the broad prairie landscape after a cool April night. A tawny hen pintail dabbles for aquatic insects in a shallow wetland recently filled by melting snow, while her handsomely plumed mate stands guard. Soon she will choose a nest site in the surrounding uplands and lay her clutch of eight olive-colored eggs.
Fortunately for this hen, the productive wetlands that have attracted her to breed in this area of Kidder County just north of Lake Josephine are situated in a landscape dominated by grassland. Through extensive research conducted on the prairies of the United States and Canada, we have learned that ducks nesting in landscapes dominated by grassland achieve high nest success. In many areas of the Missouri Coteau in the Dakotas, duck nesting success in grassland-dominated areas can exceed 40 percent, likely similar to that of pre-settlement times. DU’s research has also shown that poor duck nesting success inevitably occurs in places where the habitat base has been degraded and reduced. These results illustrate that duck production is largely determined by the quantity and quality of habitat available for breeding birds.
The good news is there are still many areas across the prairies where grassland dominates the landscape. The bad news is economic forces are now encouraging widespread conversion of prairie grassland for other uses. Demand for ethanol has dramatically increased corn prices, which has increased the demand for cropland in general and pushed up prices for other crops as well. For example, the price of wheat, the number one crop in the Prairie Pothole Region (PPR), has soared to a record $20 a bushel this spring. High commodity prices and increased demand for cropland can come at the expense of existing grassland that is vital to breeding ducks. In 2007 alone, nearly 49,000 acres of native grassland were converted to cropland across the U.S. portion of the PPR. In addition, contracts expired last year on nearly 850,000 acres of restored grassland on Conservation Reserve Program (CRP) lands in North Dakota, South Dakota, and Montana, and most of this habitat was converted back to cropland last fall.
DU and its conservation partners are focused on saving critical grasslands and wetlands on the prairies, and many landowners in the Dakotas are interested in doing the same. Currently, more than 900 landowners have offered to protect more than 412,000 acres of important waterfowl habitat with grassland easements. Unfortunately, the demand for these easements far exceeds available funding. DU is also working closely with policymakers in Washington, D.C., to ensure that rental rates for CRP are competitive with cropland rental rates. In addition, DU has been a leading advocate of a Sodsaver provision in the next Farm Bill that would make newly converted grassland ineligible for crop insurance and disaster payments.
After incubating her eggs for just over three weeks, our hen successfully hatches her brood during the third week of May. Nearby seasonal wetlands contain the perfect combination of food and cover for the hen and her ducklings. Over the next several weeks, the birds move to several different wetlands to find the invertebrates needed to nourish the ducklings’ growth and the hen’s molt.
By early July, six surviving ducklings are able to fly, and our hen is finished with her parental duties. The young birds now make daily flights in search of food to build fat reserves prior to the fall migration. In early August, our hen has replaced her flight feathers following the molt and flies east into the more intensively farmed drift plain of North Dakota, where recently harvested wheat and barley fields offer abundant waste grain and summer thunderstorms have replenished wetland habitats.
By late September, our hen, well fattened by waste grain and wetland foods, becomes restless. She joins a group of other pintails, and soon they begin their southward migration together. With only brief stops on marshes in South Dakota, the flock arrives at a large wetland complex near McPherson, Kansas, in early October.
During the fall, ducks need high-energy foods to build stores of fat that will fuel their long migration. Although waterfowl habitat was historically abundant across the southern Great Plains, wetland loss has significantly reduced the food resources available for migrating waterfowl in this region, especially during the dry early fall. Fortunately, in this part of Kansas, DU and its conservation partners have restored several thousand acres of shallow wetlands. Managed by the Kansas Department of Wildlife and Parks, this wetland complex contains extensive stands of shallowly flooded moist-soil vegetation. Our hen finds seeds produced by this vegetation especially attractive following the long flight from South Dakota.
She spends a couple of weeks here rebuilding fat reserves before continuing her migration. She doesn’t stop to rest again until she reaches Hackberry Flat Wildlife Management Area near Frederick, Oklahoma, an oasis of wetland habitat in an otherwise arid region. Once again, our hen will take advantage of moist-soil seeds produced in impoundments restored by DU and partners and managed by the Oklahoma Department of Wildlife Conservation.
After staying a week at Hackberry Flat, she regains her fat reserves and is ready for a final flight to the wintering grounds. Riding the winds behind a powerful cold front, she follows the Red River east to the Mississippi River and then turns south down the Atchafalaya River. Our hen doesn’t stop until she reaches the coastal marshes of the Atchafalaya Delta near New Iberia, Louisiana. With Halloween still a week away, thousands of ducks have already arrived on the Gulf Coast for the winter.
The Wintering Period
In south Louisiana, our hen spends her time feeding on the diverse food resources available in these coastal marshes. Once again, stores of fat are essential, allowing her to endure inclement weather or move to an area where food is more abundant or the risk of mortality is lower. But the Gulf Coast marshes are disappearing at an alarming rate, threatening the region’s capacity to support wintering populations of many species of ducks. Levees and associated flood-control projects along the Mississippi River have starved the marshes of sediment that historically sustained them. In addition, extensive channel construction has allowed salt water to infiltrate freshwater portions of the marsh, killing vegetation and causing erosion and habitat loss.
Addressing these challenges is a high priority for DU. In Louisiana, DU is working with many partners to conserve and restore degraded coastal wetlands. Farther west in south Texas, rice agriculture, which has long provided important food resources for waterfowl, has declined to record low levels. Many rice fields have been abandoned as increasing production costs have made them unprofitable for farmers. Consequently, DU and its conservation partners are working to develop former rice fields into moist-soil management units that produce seeds and other natural foods for waterfowl.
Our hen remains in south Louisiana until early January, when severe thunderstorms to the north dump more than eight inches of rain across the central Mississippi Alluvial Valley (MAV). That night, she flies north into Mississippi and settles at the confluence of the Yazoo and Little Sunflower rivers near Panther Swamp National Wildlife Refuge. Ducks are somehow able to sense when storms produce flooding rains across the flat Delta region. These weather events can flood hundreds of thousands of acres of managed and natural habitat rich in moist-soil seeds, acorns, and waste grain.
Although waterfowl habitat is abundant in parts of the MAV following heavy rains, flood-control projects and the conversion of land for agricultural production have significantly decreased the region’s wetland base. In addition, earlier harvest dates for rice, milo, corn, and other crops have greatly reduced the food available for waterfowl in fields, as waste grain has ample time to sprout, decompose, or be consumed by other wildlife before waterfowl arrive in winter. In response, DU and its conservation partners are working to restore moist-soil habitat and forested wetlands on private and public land in the MAV. The Wetlands Reserve Program (WRP) has been especially helpful in restoring and protecting important waterfowl habitat in the region. Thus far, DU has helped restore 220,000 acres of wildlife habitat on WRP projects in the MAV, primarily in Arkansas, Louisiana, and Mississippi. DU also permanently protects high-quality existing habitat on private lands with perpetual conservation easements donated by landowners.
Shortly after our hen arrives in Mississippi, she begins to attract the attention of several drakes that vie for the chance to be her mate. Following a series of elaborate courtship rituals that allow her to assess the fitness of the competing drakes, she chooses her mate. This drake will remain faithfully by her side throughout the upcoming spring migration and into the nesting period.
In early March, our pintail and her new mate begin their northward migration with the help of a strong south wind flowing up from the Gulf. Following brief stops in Arkansas and Kansas, the birds arrive at Nebraska’s Rainwater Basin a week later, just as shallow wetlands in the region are beginning to thaw. The pair settles on a recently restored wetland on DU’s 1,200-acre Verona complex near Clay Center.
During spring migration, our hen is focused on acquiring lots of food—carbohydrates to provide energy for migration and protein to produce eggs. Her diet becomes more diverse, including natural plant seeds, waste grain, and a variety of aquatic invertebrates. DU’s efforts to restore and manage wetlands in the Rainwater Basin and other spring staging areas help ensure that migrating waterfowl have enough food to return to the breeding grounds in good condition.
When a sudden cold snap in late March refreezes shallow wetlands in the region, our pair moves to the nearby Platte River, where they feed on natural foods in warm-water sloughs and waste grain in nearby cornfields. The Platte, stretching from its headwaters in Wyoming and Colorado across Nebraska, provides important habitat for waterfowl during spring cold snaps and when other wetlands are dry. But reduced river flows and rural development along the river threaten to diminish the Platte’s value to waterfowl. In response, DU is working with a host of partners to protect riparian habitat, restore adjacent wetlands, and maintain water supplies throughout this important river system.
Completing the Cycle
As the days grow longer and the weather warms in early April, our pair pushes north again into the Prairie Pothole Region. Crossing South Dakota and southern North Dakota in a few days, our hen leads her mate to the same section of prairie in Kidder County where she nested and raised her brood the year before. Soon she will establish a new nest, and the cycle of renewal will begin again.
As we saw during our hen’s travels, conserving the many habitats required to support healthy populations of waterfowl is a daunting task, but with your help, DU will meet the challenge. Fortunately, we have gained a wealth of knowledge about waterfowl populations and how habitat constraints affect the birds in different regions. Recent research has revealed that breeding habitat quantity and quality in the PPR is the most important factor influencing many continental waterfowl populations. But that doesn’t mean we should walk away from migration and wintering areas. We must continue to work in places like the Rainwater Basin, Mississippi Alluvial Valley, and Gulf Coast to ensure that as we make progress on breeding areas, waterfowl don’t face habitat shortages in other areas that could adversely affect their populations.
To maintain healthy waterfowl populations across North America, everyone who has an interest in ducks and the places they frequent will have to become more actively involved in raising funds and supporting public policies that conserve waterfowl habitats. And we’ll also have to encourage others with similar interests to do the same. The challenges facing waterfowl are great, but so are the opportunities for DU and its partners. As the acclaimed anthropologist Margaret Mead once said, “Never doubt that a group of thoughtful, committed citizens can change the world. Indeed, it’s the only thing that ever has.”
Dr. Scott Stephens is director of conservation planning at DU’s Great Plains office in Bismarck, North Dakota.