Nearly three thousand acres of former rice fields on Savannah National Wildlife Refuge are managed to benefit wildlife. The refuge includes 18 impoundments, nearly 50 miles of earthen dikes, and a variety of trunks, or floodgates. As in plantation fields, freshwater from the Little Black River is raised and lowered in these impoundments to create diverse habitats. The managed wetlands benefit fish, shorebirds, wading birds, and waterfowl, including nearly 25,000 ducks annually. Aquatic management keeps wetlands flooded for several years to encourage plants with high food value and cover for wildlife, and the impoundments also provide breeding habitat for birds, amphibians, and fish. These animals in turn are prey for alligators, river otter, ospreys, and bald eagles. Moist soil management produces shallow water and mudflat habitats, and water is drained during the growing season to promote plants preferred by wintering waterfowl, breeding birds, and other wildlife. Countless invertebrates thriving within decaying plant litter provide valuable protein for migrating shorebirds and ducks.