When we ponder the variety of waterfowl that winters in the Chesapeake Bay region, we rarely think of where these ducks, geese and swans reside the rest of the year.

Like other migratory animals, several areas are necessary for waterfowl to survive. One area is their wintering ground. And for many North American waterfowl, this is the Chesapeake Bay.

But their breeding area is even more important to these birds.

Waterfowl leave for their breeding areas in the spring. Many of the Bay’s waterfowl, especially ducks, fly west to the Allegheny Mountains, across northern West Virginia and northeastern Ohio, and continue to their final destination: the prairie provinces of North America known as the Prairie Pothole Region.

This region is characterized by small landscape depressions left behind as glaciers receded from this part of the continent. These depressions, termed potholes, collect rainfall and snowmelt, forming small shallow wetlands and lakes.

In the heart of the Great Plains, the Prairie Pothole region extends from central Iowa to north of the Canadian border, encompassing a large portion of eastern North Dakota and eastern South Dakota as well as smaller portions of western Minnesota, northwestern Iowa and northeastern Montana.

This area is vital for much of North America’s waterfowl. The Prairie Pothole Region — commonly referred to as the “duck factory of North America” because of its critical importance to breeding waterfowl — is annually responsible for producing 50 percent of the total number of ducks for eight of the 12 most common species that breed there.

Some of the Chesapeake’s wintering waterfowl that depend upon the Prairie Pothole region for breeding include the American widgeon, gadwall, mallard, shoveler, canvasback, redhead, lesser scaup, bufflehead and ruddy duck.

Large numbers of breeding ducks are attracted to the Prairie Pothole Region because of the tremendous density and diversity of wetland habitats.

Retreating glaciers carved out nearly 25 million prairie pothole wetlands. This amazing density — an average of 83 potholes per square acre is unparalleled in North America.

Duck breeding-pair densities in this area approach 120 pairs per square mile.

While most ducks instinctively return to the female’s old breeding grounds, they won’t breed and nest there unless they see an abundance of water.

But adequate water is only part of the equation. The birds also require upland cover to nest in, and the more cover they have, the better their chances of surviving and successfully hatching the eggs in their nest.

Duck production has varied greatly in the past because of erratic precipitation patterns, predators and most importantly —the loss of wetland habitat.

As it is nationwide, wetland loss is a major concern in the Prairie Pothole Region. Many wetlands have been drained or filled and much of the native grasslands have been converted to cropland.

Iowa lost 98 percent of its wetlands in this region the past century. In other states, the losses amounted to 90 percent in Minnesota, 49 percent inNorth Dakota, 35 percent in South Dakota, and 27 percent in Montana.

Thanks to habitat conservation programs and a series of wet years during the breeding season, duck production in the Prairie Pothole Region of the United States has soared to new heights in the past few years.

Landowners are learning that not only are these pothole wetlands important to ducks, but also to people. Pothole wetlands help to retain water, control flooding and improve water quality. And, the surrounding grasslands provide forage for livestock.

These wetlands also provide opportunities for fishing, hunting, wildlife watching and outdoor education.

The Prairie Pothole Joint Venture is a public/private conservation effort to protect and enhance wetland habitat.

Most prairie wetlands are privately owned. Through cooperative landowner agreements, existing wetlands and grassland can be protected or restored.

Protecting these vital breeding grounds in North America’s Prairie Pothole Region helps to ensure that waterfowl will continue to grace our