And so the annual reproductive cycle of waterfowl ends and the long journey south to the birds' wintering grounds begins. Most of North America's waterfowl undertake annual long-distance movements between their breeding and wintering areas in fall and spring. Migration is a crucial period for ducks and geese, primarily because of the physiological demands posed by flying long distances. A duck in flight burns 12.5 times more energy than one at rest. Spring migration is even more taxing for female waterfowl because many species rely on stored fat accumulated on staging areas to produce eggs and to provide energy to sustain them while nesting.
Historically, migrating waterfowl found abundant wetlands along the flyways, where the birds could stop and refuel during their long journeys. Unfortunately, the landscape has changed dramatically on many of North America's most important waterfowl staging areas. The United States has lost nearly 50 percent of its historical wetlands, with losses in states such as California and Ohio exceeding 90 percent. In addition, the habitat requirements of migrating waterfowl vary considerably among species. Consequently, to meet the needs of North America's diverse waterfowl populations, we must provide a variety of habitats for the birds, in the right places and at the right times.
So how do we determine what types of habitat and how much is needed to support healthy waterfowl populations? The most widely accepted approach is the use of bioenergetic models. These models are extremely useful in estimating how much habitat is required to support waterfowl and in assessing the capacity of the existing habitat base to support ducks and geese on key landscapes. DU and its joint venture partners are currently using these models to determine the amount of habitat that will be required in high-priority areas to meet the goals of the North American Waterfowl Management Plan. Ultimately, these planning efforts are guiding the on-the-ground habitat work being delivered by DU and its partners to benefit waterfowl during the migration period. Let's take a closer look at DU's conservation programs on important waterfowl staging areas across the United States, and how these efforts are helping to meet the needs of ducks and geese during this crucial part of their annual cycle.
North Atlantic and Mid-Atlantic Coast
Consisting of a chain of extensive estuaries and associated wetlands, the North Atlantic and mid-Atlantic Coast stretches from Maine south to the Chesapeake Bay of Virginia. This region boasts a remarkable diversity of highly productive wetland and adjacent upland habitats, including vast beds of submersed aquatic vegetation, intertidal mudflats, tidal salt marshes, tidal freshwater marshes, and maritime forests. Draining into these estuaries are major rivers and their tributaries, which merge into a network of tidal channels and bays before ultimately flowing into the Atlantic Ocean. Farther inland, important habitats include coastal plain intermittent ponds, swamps, upland forests, and agricultural crops.
These diverse habitats support 34 waterfowl species, most notably Atlantic brant, American black ducks, canvasbacks, and a variety of sea ducks. Regrettably, nearly 7 million acres of wetlands have been lost or severely degraded from Maine to Maryland. Thus, a primary focus of DU's conservation work in this region is to protect and enhance remaining coastal wetlands.
A prime example of DU's work along the Atlantic coast is the Supawna Meadows National Wildlife Refuge (NWR) project in New Jersey. With funding from a North American Wetlands Conservation Act grant administered by DU, the U.S. Fish and Wildlife Service (USFWS) will acquire and permanently protect two tracts of land encompassing 182 acres, including 100 acres of estuarine marsh. These acquisitions will expand this 3,020-acre refuge, providing additional staging and wintering habitat for American black ducks and a variety of other Atlantic Flyway waterfowl. Supawna Meadows NWR is also open to the public for waterfowl hunting, wildlife viewing, photography, and environmental education.
The five Great Lakes have a coastline exceeding 10,900 miles, encompass a total area of almost 95,000 square miles, and hold approximately 20 percent of the world's freshwater. These inland seas were formed by glaciation, which also sculpted the surrounding landscape to form a variety of productive waterfowl habitats, including pothole, scrub-shrub, and forested wetlands; shallow lakes; freshwater coastal estuaries; and river flowages. These wetland systems support continentally significant numbers of migrating ducks, geese, and swans. Unfortunately, intense agricultural, industrial, and urban development have resulted in substantial wetland losses and degradation across this region. An estimated 60 percent of historical Great Lakes wetlands have already been lost, and the region continues to lose an estimated 1 percent of its remaining wetlands each year. Land-use changes have resulted in excessive contaminant, nutrient, and sediment inputs into wetlands, lakes, streams, and rivers, threatening water quality for people and wildlife. In addition, introduced species, such as carp and common reed, have further degraded remaining habitats.
To address these issues, DU has made the restoration of riverine and coastal marshes a primary focus in the Great Lakes region. A good example of our work here is the Maankiki Marsh restoration on Shiawassee NWR in Michigan. DU and the USFWS worked together to reconnect 1,250 acres of wetland habitat to the Shiawassee River, transforming former agricultural fields into a vast expanse of emergent wetlands that provide abundant, high-energy seeds and invertebrates for migrating waterfowl. This project, which also offers vital habitat for other wildlife, improves water quality, and helps control flooding, was funded in part by a $1.5 million National Fish and Wildlife Foundation—Sustain Our Great Lakes grant via the Great Lakes Restoration Initiative. Saginaw Bay Watershed Initiative Network, Dow Chemical Company, and DU provided additional financial support. Shiawassee NWR is a popular public recreation area for hunters, anglers, wildlife viewers, and photographers.
Upper Mississippi River
Wetlands associated with the Upper Mississippi River and its tributaries are vital to migrating waterfowl, providing stopover habitat for an estimated 5 million to 9 million ducks in the region's western portion alone. Floodplain wetlands in this ecosystem include bottomland forest, scrub-shrub and emergent wetlands, mudflats, and beds of submersed aquatic vegetation. These habitats, which support 32 species of waterfowl during migration, are especially important to mallards, wood ducks, canvasbacks, and lesser scaup.
The once-expansive bottomlands of the Upper Mississippi River watershed have been largely converted to other uses. More than two-thirds of the region's historical wetlands have been lost, and additional wetland losses continue at the rate of approximately 1 percent per year. These land-use changes have resulted in a variety of water-quality issues as excessive contaminant, nutrient, and sediment loads are deposited in wetlands, lakes, streams, and rivers. Consequently, a top priority for DU and its partners is the protection and restoration of remaining bottomland habitats of high importance to migrating waterfowl. In southern Illinois, for example, DU partnered with the U.S. Forest Service to enhance a 390-acre greentree reservoir in Oakwood Bottoms, a popular public hunting area in Shawnee National Forest. This project entailed a variety of timber-stand improvements, including selective cutting of less desirable trees and the supplemental planting of mast-producing pin oaks and other hardwood tree species, as well as improvements to the area's water-level management infrastructure. These efforts will allow high-quality bottomland hardwood forest to regenerate, providing a rich source of high-energy acorns and other foods for migrating mallards and wood ducks and improved hunting opportunities for waterfowlers.
Minnesota and Iowa
Most of Minnesota and northern Iowa's landscape was formed by glaciers 10,000 to 15,000 years ago, creating tens of thousands of wetlands and shallow lakes. These wetlands ranged in size from small seasonal and temporary basins in the south to deeper, more permanent palustrine wetlands and large shallow lakes in the north. Early pioneers described portions of southern Minnesota and northern Iowa as virtually impassable during spring and early summer due to the abundance of prairie wetlands, which provided crucial breeding and migration habitat for spectacular numbers of waterfowl. Unfortunately, the fertile soil and the strong work ethic of the region's hardy settlers led to an almost total loss of wetlands in areas suitable for agriculture.
Today, the remaining large wetlands and shallow lakes of Minnesota and Iowa serve as vital stopover areas for waterfowl and other birds migrating between their southern wintering areas and northern breeding grounds. These lakes and wetlands are of particular importance to migrating diving ducks, especially lesser scaup and ring-necked ducks. DU's primary focus on this landscape is the protection and enhancement of remaining shallow lakes and the restoration of small wetlands and associated prairie uplands for migrating and breeding waterfowl.
A good example of DU's work in this region is the Smith Lake project in Minnesota. Traditionally, Smith Lake provided excellent foraging habitat for migrating waterfowl, but over time invasive carp and poor water quality diminished its productivity. In 2005, Ducks Unlimited worked with the Minnesota Department of Natural Resources to design and install a high-velocity fish barrier downstream of Smith Lake. The fish barrier was initially effective, but mild winters and high water levels allowed undesirable fish species to become reestablished. In response, DU designed a new water-control structure, which enabled lake managers to temporarily lower water levels to eliminate nuisance fish and rejuvenate lake vegetation and associated invertebrate populations. Since this project was completed, water quality has vastly improved, vegetation has returned, and waterfowl use has increased dramatically.
Nebraska's Rainwater Basin
Located on the High Plains of south-central Nebraska, the Rainwater Basin annually hosts some of the most spectacular concentrations of migrating waterfowl in the world. Each spring an estimated 7 million to 9 million ducks and 2 million to 3 million geese visit wetlands in this area to rest and refuel on their way north. Historically, the region boasted some 11,000 wetlands, which totaled more than 200,000 acres of prime waterfowl habitat. Today, only about 10 percent of the Rainwater Basin's wetlands remain intact, and these habitats play a central role in supporting continental waterfowl populations during migration.
DU's work in the Rainwater Basin focuses on protecting remaining wetlands and restoring hydrology to degraded basins. For example, DU recently purchased a 50-acre parcel of private land that contained the remainder of a large wetland basin on the adjacent Heron Waterfowl Production Area (WPA). This acquisition enabled a portion of a county road to be removed, further restoring the natural hydrology of this 217-acre wetland. In addition, a concentration pit on the WPA was filled, allowing runoff to spread evenly across the wetland basin to provide productive shallow-water feeding habitat for migrating dabbling ducks and other waterbirds.
Southern Oregon−Northeastern California
The Southern Oregon−Northeastern California (SONEC) region lies in the west-central portion of the Great Basin. This unique landscape's topography is generally "basin and range," where water supplies are derived mainly from snowmelt and seasonal precipitation. Its rich mosaic of wetlands, wet meadows, and irrigated pastures provides vital migration habitat for Pacific Flyway waterfowl, especially northern pintails. Of particular importance are grazed or hayed surface- irrigated pastures that provide abundant succulent vegetation, seeds, and invertebrate food resources for migrating waterfowl. In fact, approximately half of all wintering ducks in the Central Valley of California and one-third of the continent's northern pintails stop to feed and rest in the SONEC region in spring, and these birds rely heavily on surface-irrigated pastures for foraging habitat while they are here.
Unfortunately, changing irrigation practices now threaten waterfowl and other wetland wildlife in the SONEC region. Surface-irrigated acres have declined by 40 percent, as many ranchers have switched to center-pivot sprinkler irrigation to reduce costs and improve water-use efficiency. However, sprinkler irrigation does not create the shallow flooding conditions that provide ideal foraging habitat for waterfowl. In response, DU is working with the USDA Natural Resources Conservation Service to help ranchers maintain surface-irrigation practices in historical floodplains through the Environmental Quality Incentives Program. Nearly 6 million acres of surface-irrigated ranchlands remain in the West, and great potential exists for conserving these key habitats in the SONEC region and other areas of high importance to migrating waterfowl.
Migration is a pivotal event in the annual cycle of North America's waterfowl. To meet the physical demands posed by long-distance flights and subsequent breeding activities, waterfowl require diverse and abundant foraging and resting habitats on key staging areas. That's why DU and its partners are working hard to ensure that waterfowl encounter abundant, high-quality wetlands throughout their long journeys, so the birds can return to the breeding grounds each spring in prime condition and begin the cycle again.
Dr. John Coluccy is director of conservation planning in DU's Great Lakes/Atlantic Region.