Survival, recruitment, and management of box-nesting populations of wood ducks in Mississippi and Alabama.

摘要

I estimated survival of radiomarked female wood ducks (Aix sponsa ) and ducklings in different wetland environments in Noxubee National Wildlife Refuge (NNWR) in Mississippi from 1996–1999 and in the Tennessee-Tombigbee Rivers Waterway (TTRW) in Alabama during 1998–1999. Survival of brood rearing females was 0.90 ± 0.05 (± SE) at NNWR and 0.92 ± 0.07 at TTRW. Survival of 300 radiomarked wood duck ducklings ranged from 15% (95% CI = 4–27%) to 24% (95% CI = 13–38%) among years and was 21% (95% CI =15–28%) overall at NNWR during 1996–1999. Survival of 129 radiomarked ducklings was 29% in both 1998 (95% CI = 20–41%) and 1999 (95% CI =13–45%), and 29% (95% CI = 20–40%) overall at TTRW.; I used Akaike Information Criteria to examine biotic and abiotic effects on duckling survival. At NNWR, the best predictor model contained all measured variables (i.e., hatch date, brood size at nest departure, duckling mass on hatch date, distance moved by ducklings between days, hen age [yearling or adult], hen mass at end of incubation, site-habitat types, ambient temperature, rain, and the interaction of the latter 2 variables). At TTRW, the best model included brood size and inter-day movement distance. Although there were 4 competing models of duckling survival at TTRW, I found strong evidence that inter-day movement distance and brood size were important. Ducklings that traveled to scrub-shrub habitats away from their hatching site at NNWR and TTRW had highest 30-day survival rates, ranging from 58–71%.; I identified 13 agents of duckling mortality and estimated cause-specific mortality rates from 234 and 90 deaths of ducklings at NNWR and TTRW, respectively. Avian (n = 155; 46%) and aquatic (n = 79; 23%) predators were most important at both areas and in all years.; Thirty-five-62% and 38–65% of duckling recruitment occurred from first and second uses of large nest boxes, respectively. Forty-five-87% and 13–55% of duckling recruitment resulted from first and second uses of small boxes, respectively. Removing unhatched eggs and nest materials from boxes during the breeding season and locating boxes near suitable brood-rearing habitats (e.g., scrub-shrub) may promote fall recruitment of box-nesting populations of wood ducks.