Bottomland hardwood forests provide forage and other important resources for wintering and breeding waterfowl in the Southeastern United States. My objective was to conduct an initial investigation of possible influences of habitat features, flood events, and human disturbance on relative abundances of wintering ducks in Delta National Forest (DNF), Mississippi. I surveyed 65 wetlands in DNF 17 times from November 2012 to March 2013 and analyzed abundance data from wood ducks (Aix sponsa), mallards (Anas platyrhynchos), gadwalls (Anas strepera), and hooded mergansers (Lophodytes cucullatus). Waterfowl abundance varied by species but generally increased during major flood events and on wetlands having an approximately equal interspersion of scrub-shrub and open water consistent with the “hemi-marsh” concept. I recommend partial removal of scrub-shrub from selected wetlands to promote emergent plant communities and increased duck use and experimental evaluation of waterfowl responses to management of wetlands and human activities during winter in DNF.

Dans une ville de Vilnius, la structure et la division des populations d’oiseaux hivernants étaient faites des recherches en 2003 – 2005. Ainsi que dans les étangs des régions de Neris, Vilnelė et de Žvėrynas. Pendant la période des recherches les neuf espèces d’oiseaux migrateurs étaient aperçues: le canard colvert, le harle bièvre, la mouette rieuse, la poule d’eau, le fuligule milouin, le garrot à œil d’or, le grèbe huppé, le foulque macroule, le cygne muet. Pendant des recherches de différents saison dans toutes les gisements d’eau de Vilnius on rencontre le plus souvent le canard colvert et le harle bièvre. La mouette rieuse était trouvée aussi dans toutes les gisements d’eau, mais l’abondance de la mouette rieuse s’accroîssait seulement pendant la période de la migration d’été. Le plus grandes agglomérations des canards colverts on trouve dans les étangs de Žvėrynas, Vilnelė et à coté de la région d’Antakalnis. Dans ces endroits les canards sont nouris toujours. Des endroits pour hiverner le plus importants pour le harle bièvre sont dans une rivière Neris à coté d’un parc Vingis, à Vilnelė et à Neris à coté de la région d’Antakalnis. Pour appréciér l’abondance des oiseaux en 2003 – 2004 et en 2004 – 2005 pendant des saisons d’hiver l’abondance de la population a changé seulement du harle bièvre: en 2004 – 2005 en hiver la population de cette espèce d’oiseaux était plus petite que en hiver dernièr.

Estimates of abundance are critical to manage and conserve waterfowl and their habitats. Most surveys of wintering waterfowl do not use probability sampling; therefore, development of more rigorous methods is needed. In response, I designed and evaluated an aerial transect survey to estimate abundance of wintering ducks in western Mississippi during winters 2002?2004. I designed a probability-based survey using stratified random and unequal probability sampling of fixed-width transects. To correct for visibility bias inherent in aerial surveys, I conducted an experiment to model bias and incorporated correction factors into estimation procedures to produce adjusted estimates. Bias-corrected estimates were most accurate. Precision of abundance estimates of total ducks met a priori goals (CV ≤ 15%) in 10 of 14 surveys. Based on a simulation study, the implemented survey design provided the most precise estimates, yet certain refinements remained possible. I also illustrated potential applications of survey results in the context of conservation and management of wintering waterfowl populations and habitats. I described patterns of abundance within and among winters, including a comparison with surveys conducted during winters 1988?1990 that revealed mallard abundance decreased 65% from the late 1980s. I developed a method to illustrate population abundance spatially for scientific and public education. I attempted to explain temporal variation in abundance estimates relative to variables potentially representing hypotheses explaining regional distributions of ducks. I concluded the data provided stronger support for factors related to energy conservation by ducks than factors related to energy acquisition. Finally, I determined associations between duck distributions and habitat and landscape features in accordance with the habitat-complex conceptual model. Landscapes with greater interspersion and diversity of wetlands attracted increased numbers of ducks, a though other factors such as wetland area also were important. I concluded that this study advanced methodologies to survey wintering waterfowl. Although improvements were warranted, I recommend this survey design for continued monitoring of wintering ducks in western Mississippi. Furthermore, I suggest habitat management on public and private lands should include complexes of seasonally flooded cropland, moist-soil, forested, and permanent wetlands to potentially increase wintering duck numbers in western Mississippi.