Habitat use and response to wetland management practices of non-breeding dabbling ducks in western Tennessee

Western Tennessee is an important area for non-breeding waterfowl in the Mississippi Flyway, including over 40% of the Mississippi Flyway population of American black ducks (Anas rubripes, hereafter black ducks), a species in decline. Information is lacking on waterfowl community ecology in the region, and managers must identify key habitats and consider functional use and potential predictors of resource use by non-breeding communities. Impacts of wetland management practices, such as moist-soil disking and subsequent planting of desirable grasses (i.e., Japanese millet [Echinochloa frumentacea], hereafter millet), must also be tested relative to impacts on waterfowl use and habitat quality. During winters 2011–2013 (November–February), I estimated food densities, diurnal habitat use, activities, and potential predictors of use of dabbling ducks (Anatini) at the Duck River Unit of Tennessee National Wildlife Refuge and Cross Creeks National Wildlife Refuge in western Tennessee, and I interpreted patterns relative to black ducks observed in concurrent studies (Chapter II). I also estimated autumn vegetation response, dabbling duck use and activities, and food densities in moist-soil wetland plots disked and planted with millet (Chapter III). Dabbling ducks primarily used moist-soil areas, and foraging was the dominant activity. Mudflats and scrub-shrub areas were also used as foraging areas. Habitat use was positively correlated with increasing emergent cover and energetic carrying capacity and was negatively correlated with increasing water depth. Black ducks occurred with other Anatini species in each habitat type, especially in moist-soil and scrub-shrub areas. Food densities were initially greatest in moist-soil areas, but foods declined rapidly. Vegetation was taller and percent cover of desirable species greater in un-manipulated than disked wetland plots, but duck use and food densities did not differ between treatments. Foraging was more frequently observed in disked than un-manipulated plots. Disking and millet planting did not improve wetland use by black ducks. My results suggest that managers should provide a complex of natural wetland types to accommodate non-breeding dabbling duck communities in western Tennessee. Disking and millet planting should not be used to improve moist-soil wetlands for black ducks, and other wetland manipulation techniques should be investigated.