Activity Budgets and Food Resources for American Black Ducks Wintering in Western Tennessee

Joshua M. Osborn, Matthew J. Gray, Heath M. Hagy, Matthew D. McClanahan

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Abstract

American black duck (Anas rubripes, hereafter black duck) populations have declined by >50% since the 1950’s, with the greatest declines in the Mississippi flyway (Conroy et al. 2002). Little data exist detailing habitat selection and effects of management practices on black ducks in the interior U.S. During November-February 2011-2013, we observed black duck behavior and abundances and sampled food resources in six habitat types (mudflats, moist-soil wetlands, open water, submerged aquatic vegetation (SAV), flooded forest and shrub edges, and unharvested, manipulated corn fields) at the Duck River Unit of Tennessee National Wildlife Refuge and Cross Creeks National Wildlife Refuge in west-central Tennessee. At TNWR, black ducks had the highest foraging rates in moist soil (31.1%) and flooded corn (46.7%) and the lowest foraging rates in flooded forests (10.6%). Moist-soil wetlands contained the greatest density of foods at both refuges (1001.8 kg/ha), followed by mudflats (317.2%) and flooded forests (168.4 kg/ha) at TNWR and CCNWR, respectively. Food was abundant in SAV areas during late November (630.6 kg/ha) at both refuges but declined rapidly as winter progressed. Black duck densities and foraging effort correlated positively in moist-soil and SAV in early winter. Interestingly black duck densities were greatest overall in flooded forests, but these habitats generally contained relatively low food densities and ducks typically did not forage there. We suggest flooded forests may be important for life-history strategies other than energy acquisition (e.g., pair bonding, thermoregulation, predator avoidance) and that diurnal black duck habitat selection is a function of factors other than food availability. Black ducks, like other waterfowl, appear to require a complex of different habitats to meet their daily requirements (Pearse et al. 2012). Conservation planners should consider factors other than energetic carrying capacity when prioritizing wetland conservation and restoration activities for species such as the American black duck.
Original languageEnglish (US)
StatePublished - 2014

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Keywords

  • INHS

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