What Do We Manage For?
Tennessee National Wildlife Refuge's diversity of habitats supports breeding, wintering, and/or migration habitat for 301 bird species, and habitat for 51 mammals, 89 reptiles and amphibians, and 144 species of fish. This refuge serves as an important wintering ground for thousands of migratory waterfowl each year, as they travel through the Mississippi Flyway. The refuge winters approximately 150,000 ducks and 6,000 geese. In some cold winters the refuge has been known to exceed a peak of 250,000 ducks. During the last ten years geese have peaked at 19,000 and ducks have peaked at more than 321,000.
The refuge is also a significant wintering area for American black ducks within the Mississippi Flyway, with the peak averaging around 10,000 each year. Historically, the refuge wintered 20-30% of the black ducks occurring in the Mississippi Flyway. In the past, the refuge has been a site for American black duck research projects.
Wood ducks are an important species harvested in Tennessee and the southeast, often ranking number 1 or 2 in ducks retrieved by the hunting public. Other duck species present in significant numbers during fall and winter include the mallard, gadwall, American wigeon, blue-winged teal, American green-winged teal, northern pintail, ring-necked duck, canvasback, lesser scaup, bufflehead, common goldeneye, and ruddy duck.
King Rails regularly nest in the moist soil habitats on the Duck River Unit, one of the few known nesting sites in Tennessee. Their populations have significantly declined in recent years and are now the highest priority marshbird in this region, King Rails may serve as an umbrella species for other priority marshbirds.
Although the Interior Low Plateaus may not be considered among the most important regions in eastern North America for supporting migrant shorebirds, there are still significant shorebird populations moving through the region and in particular the Tennessee River Valley. The refuge seeks to provide habitat in the managed impoundments of the Duck River Unit for both northbound and southbound migration, with an emphasis on southbound migrants.
Grassy Lake on the Duck River Unit historically supported a large colony of primarily Great Blue Herons. However, the colony has declined recently as the birds moved off to other areas and established several smaller nesting colonies. The decline appears to be simply a case of tree die-off and movement of the birds to other suitable habitats.
The refuge’s habitat is also vitally important for land bird populations. A 2005 study on the Big Sandy Unit demonstrated that the Big Sandy Unit’s oak-hickory forest supports 55 species of forest nesting song birds. Each year around ten pairs of Bald Eagles nest on the refuge. During the wintering season large trees along the shoreline provide multiple eagle roosts during winter.
The refuge’s importance to populations of waterfowl and migratory birds has resulted in the refuge’s designation as a Globally Important Bird Area by the American Bird Conservancy. American Bird Conservancy’s Important Bird Areas Program was launched in 1995 and has concentrated on identifying and documenting the top sites in all 50 states.
How Do We Manage For Wildlife?
Habitats Available on the Refuge
Tennessee NWR encompasses 51,358 acres and is composed of three separate units; the Duck River Unit (26,738 acres), the Big Sandy Unit (21,348 acres) and the Busseltown Unit (3,272 acres). All three units are located along a 65-mile reach of the Tennessee River.
There is a total of 3,000 acres of farmed cropland on all three units, with approximately 700 acres on the Big Sandy Unit, 1600 on the Duck River Unit, and 700 acres on the Busseltown Unit. This land is farmed each year through cooperative farming agreements to provide supplemental food and cover for the thousands of waterfowl. In addition, approximately 1,400 acres in the Duck River Bottoms are managed for native wetland plants, or also called moist-soil vegetation. These bottoms are compartmentalized by a series of levees and water control structures that allow water levels to be controlled for optimum waterfowl food production.
The refuge contains approximately 20,000 acres of forest, with the majority being comprised of upland stands that are predominantly oak-hickory. Small isolated blocks of bottomland hardwoods occur on the Duck River and Busseltown units. Most of these stands are dominated by light seeded species such as maples, sweetgum, and green ash. The remainder of refuge not falling into the forested, agricultural, or moist-soil categories primarily consists of open water habitats.
Migratory birds and other wildlife benefit from several direct habitat management activities on Tennessee NWR. Approximately 1,600 acres of Refuge habitat managed as moist soil units are created through water level manipulation. Water level management within large impoundments create high quality moist-soil habitats and provides flooded agricultural fields for waterfowl and other wildlife. During the spring and summer on the refuge, water is removed from the shallows of some impoundments to allow for the germination of natural wetland plants and the invertebrates attracted to these wetlands. After the plants have matured and produced an abundance of seeds, the impoundments are flooded. Waterfowl and other marsh birds feast upon these natural seed sources. Drawdowns in the moist soil areas also produce mudflats that nourish shorebirds during their spring and fall migrations.
This refuge supports wood duck reproduction success with an active wood duck nest program. Large numbers of "woodies" can be found in refuge wetlands, nesting in artificial nest boxes, and in natural tree cavities. These nest boxes are also beneficial to a number of hooded mergansers that nest on the refuge. Each year during late summer, a wood duck banding is conducted in which refuge employees attach bands to the legs of these colorful "summer ducks" in order to gather information about hatching success, survival and harvest pressure.
A cooperative farming program is coordinated for the primary purpose of providing food and other needed habitats for waterfowl and other wildlife. Under this program, select refuge lands are offered to local farmers for agriculture. In exchange for a share of the crop, local farmers cultivate and plant the refuge's lands to produce corn, millet, and winter wheat for waterfowl. The refuge's share is left unharvested in the field. Flooded agricultural fields of unharvested crops draw ducks and geese onto the refuge where they are able to feed and rest. Healthy, well-nourished ducks and geese depart the refuge in early spring.
Currently inactive, a forest management plan has been developed for the refuge to carefully alter the forest structure to produce more understory vegetation. This type of forest management can improve habitat for nesting songbirds and many other species of wildlife.
In addition to the managed habitats, there are several naturally occurring habitats such as mudflats that aren't actively managed by the refuge, but are extremely important to many species of wetland wildlife. The primary role the refuge plays associated with these habitats is protection.
Currently the refuge has an active wildlife and habitat survey program which monitors winter waterfowl populations, moist-soil and agriculture habitats, shorebirds, eagles, wood ducks and songbirds.
The refuge also provides habitat and protection for several species listed under the Endangered Species act. The listed species that occur or have been known to occur on refuge are the bald eagle, least tern, wood stork, piping plover, and the pink mucket, ringpink, and orangefoot pimpleback mussels. Endangered species that potentially occur or have occurred on the refuge are the pygmy madtom, and the rough pigtoe, fanshell and white wartyback mussels.