 A presentation of the United States Fish and Wildlife Service. Every fall, as they have for countless centuries, geese, ducks, shorebirds and other migratory birds leave their northern nesting grounds and fly southward before the grip of winter titans. They migrate along well-defined ancient routes as surely as we follow a highway. One heavily used route, called the Atlantic Flyway, leads over the Chesapeake Bay down the Delmarva Peninsula to what is now known as Blackwater National Wildlife Refuge. Blackwater was established by Congress in 1933 as a refuge where these long-distance travelers could rest and feed in peace. There had been a growing concern during the early part of the century that the loss of wetland habitat as well as overhunting was causing an alarming decline in waterfowl and other wildlife populations. Out of this concern, a nationwide system of wildlife refuges, many situated along the migratory flyways, was born. Today, as the 100th anniversary approaches of when the first refuge was established by President Teddy Roosevelt in 1903, there are more than 500 national wildlife refuges across the nation, managed by the U.S. Fish and Wildlife Service. The mission of the National Wildlife Refuge System is to administer a national network of lands and waters for the conservation, management and, where appropriate, the restoration of the fish, wildlife and plant resources and their habitats within the United States for the benefit of present and future generations of Americans. For well over half a century, Blackwater National Wildlife Refuge has been supporting this mission. The tidal marshes along the Blackwater River have always been a haven for ducks. When Blackwater came into being during the 1930s, ducks were the primary visitors to the refuge. There were few geese. All that changed when mechanical corn pickers came to the area during the early 1940s. While the dried corn was being stripped from the cob, enough was spilled on the ground to attract migrating geese to this high-energy food. Over the next few decades, the number of geese that no longer continued their migration to their traditional southern wintering ground steadily increased. By the 1960s, the number that stopped at Blackwater had grown to more than 100,000. They congregated on Blackwater because the refuge offered protection and there was plenty of food in the surrounding marshlands and farm fields. Farming became an integral part of wildlife management on Blackwater. Clover and buckwheat are planted for protein, which the birds need for muscle building and feather replacement. Corn and sorghum are also planted to provide high-energy carbohydrate foods that the birds eat to build body reserves for the long flight back to their northern nesting grounds in the spring. The freshwater impoundments are a haven for the tens of thousands of ducks that pass through Blackwater on their migrations. Several species of ducks, known as dabblers, feed on vegetation and small invertebrates that live on the bottom of these freshwater impoundments. To provide food for dabbling ducks and other water birds, the refuge uses a method called moist soil management to encourage the growth of nutritious plants in the impoundments. In summer, when migratory waterfowl have gone, the impoundments are drained to allow moist soil seed-bearing plants, such as tixeed sunflower, a chance to become established. When plants with little wildlife value, such as cocklebur, begin to crowd out the sunflowers and other beneficial plants, the impoundments can be flooded to kill unwanted plants. In the fall, the impoundments are filled to a depth between 6 and 10 inches, so that when the ducks arrive, a feast lies just below the surface. For this to work, timing is essential, as well as an ample supply of freshwater that can be moved by gravity through the complex of connected impoundments. Rain is the primary source of freshwater. Through ditches dating back to colonial times, water flows from the 5,000-acre Kentuck swamp on the north side of Key Wallace Drive into the impoundments. During a drought emergency, water can be pumped from a series of wells to keep the system operating. Another challenge is to make sure that saltwater doesn't intrude into the freshwater impoundments and affect the plants. Salinity levels are therefore closely monitored. Several impoundments can be seen on the north side of Wildlife Drive. Many more are located on other parts of the refuge, and additional impoundments are being constructed each year. These man-made, intensively-managed impoundments make it possible for the refuge to provide food and protection for many thousands of waterfowl, wading birds, songbirds, shorebirds, and other wildlife. Blackwater is much more than croplands and impoundments. Over half of the refuge is forested with stands of tall loblolly pine, ideal nesting habitat for bald eagles. There are more than 30 active eagle nests in and around the refuge, the largest concentration north of Florida. The forest also provides habitat for the endangered Delmarva fox squirrel, a stocky, bushy-tailed cousin to the common graysquirrel. Delmarva fox squirrel populations were reduced throughout their range when their forest habitat was cut down. Today, the largest contiguous forested tract with a healthy population of fox squirrels is on Blackwater. Refuge staff carefully monitor squirrel populations by periodic trapping to record health data. In recent years, the population has grown large enough so that some squirrels can be transplanted to other areas to establish new colonies. When the weather cools, the squirrels retreat into one of the many nesting boxes on the refuge. Here the squirrels give birth during winter. For refuge biologists, this is an ideal time to record nesting success and track population trends. Winter is also an ideal time to capture and band Canada geese. The refuge's banding activities are part of a national program that tracks the movements of geese and other waterfowl. During banding, the sex and age of the birds are recorded. The band numbers become part of a national database. When a bird is recaptured or dies and the band is returned, valuable information about its life history is revealed. The data helps scientists learn about survival rates and predict population trends. Banding is also used to monitor wood duck populations, one of the duck species of management concern that had once experienced a significant decline in numbers. Wood ducks prefer cavities in old trees for nesting, but when the old growth forests were cut, nesting sites were lost and the population suffered. When nesting boxes designed for wood ducks were introduced, the ducks quickly accepted them. Today thousands of boxes have been installed across the country and wood duck numbers have increased. Refuge staff also lend a helping hand to osprey nesting efforts. Ospreys, also known as fishawks, can be found worldwide. The ospreys on the refuge migrate each fall to South America, returning in the spring to raise another brood. Ospreys like bald eagles and peregrine falcons suffered when DDT entered the food chain. The pesticide was linked to the thinning of their eggshells and few young hatched. Today with the elimination of DDT and the protection of key habitats, osprey populations are recovering. Also doing well, in fact too well, are the resident Canada geese that no longer migrate to their northern breeding grounds to nest. These geese, whose numbers are rapidly increasing, are becoming a nuisance wherever they take up permanent residents. Also a nuisance for wildlife managers are mute swans, whose regal beauty disguises an efficient marsh destroyer. The mute, distinguished by the black knob on its orange bill, was introduced from Europe and is rapidly spreading. Mute swans are aggressive nesters, displacing other birds. They feed by pulling out the plants from wetland bottoms, speeding the destruction of the marsh. The most threatened wildlife habitat on the refuge is the marsh. During the past 60 years, 8,000 acres, more than 12 square miles, have disappeared beneath the waves. A loss not only to waterfowl, but also to the Bay's aquatic life. The reasons for the loss are complex and not fully understood. Scientists speculate that two events are happening at the same time. Sea level rise and land subsidence. Global warming is thought to be the reason for sea level rise, as glaciers and the polar regions melt under rising temperatures. The land under the marshes is also slowly sinking, as groundwater is pumped out for human use. The cumulative result has been that water levels have risen 6 inches during the past 100 years. This house on Barron Island, one of several islands that are part of Blackwater Refuge, once stood high and dry, far from the water's edge. There once was a lawn, boat docks, and a beach, all now swallowed up by the rising waters. Today, Barron Island is only a fraction of its former size. It too may one day slip below the rising waves, as have so many other islands in the Chesapeake Bay. If, and when it goes, gone too will be one of the Bay's most productive, wading bird rookeries. Herons and egrets now nest on Barron Island by the hundreds. The magnificent birds born on this island can be seen throughout the Chesapeake Bay area. Not much can be done at the local level to stop sea rise or land subsidence. What can be done is to preserve and protect what remains. A major culprit in marsh loss is a large rodent introduced from South America, the Nutria. Nutria destroy the marsh by digging up plants and eating the roots. Their excavations accelerate marsh erosion. And these rodents are prolific breeders. Nutria were brought into the area during the 1940s to be raised in captivity for their fur. At the time of their introduction, the marshes around Blackwater were filled with muskrats and the fur trade was flourishing. A few nutria escaped and today there are tens of thousands destroying the marsh. The refuge issues permits to muskrat and nutria trappers to remove these rodents. But trapping hardly makes a dent in the numbers. Invasive plants are also taking their toll on the marsh. Fragmites is a hardy plant and difficult to control. It quickly crowds out other plants destroying the natural diversity in the marsh. Refuge biologists closely monitor the health of the marsh by conducting periodic surveys. They record the diversity, distribution and growth rate of the plants in their sample plot. While these surveys become part of the long-term record of the marsh, they also serve as the basis for current management strategies such as when to burn the marsh. Fire is a tool used to maintain and invigorate the marsh. Without fire, the dead plant material chokes off new growth. The plants that emerge after burning provide food for waterfowl and the new root system binds and strengthens the frail marsh. Burning the dead material also reduces the risk that lightning strikes become uncontrolled destructive wildfires. To compensate for the continuing loss of marsh habitat, the refuge is expanding by acquiring lands from willing sellers. During the fall and spring, blackwater is a crucial resting and feeding stop for thousands of migrating birds representing many species. Blackwater is also a magnet for all those who love nature. Visitors come from around the world to marvel at the wondrous spectacle. Blackwater also very much belongs to its surrounding human community of Dorchester County and Maryland's eastern shore. And what happens is that there's a piece of corn back here, squirrel walks in, steps on this pan, and the door closes. Your Canada geese and your snow geese. For many school children, blackwater is their first up-close introduction to the natural world of wetlands and wildlife. The refuge is a marvelous classroom and its environmental education program, a wonderful way to breathe life into a student's biology lessons. Several times during the year, the refuge, together with the Friends of Blackwater, a volunteer organization, offers demonstrations and guided talks that explain some of the wildlife-related activities that take place at the refuge. Volunteers are an important part of what makes blackwater work. More than a hundred volunteers contribute over 10,000 hours a year staffing the visitor center and helping with many public use and biological activities. Blackwater provides benefits to people as well as to wildlife. Not only is it a great place to observe and photograph wildlife, but there's hiking and birdwatching, biking and fishing, and limited hunting opportunities as well. Blackwater is a story of challenges met and promises kept. A place that benefits both its wildlife clients and its owners, the American people. Please help us protect this area for future generations.