Survival of Wood Duck Ducklings and Broods in Mississippi and Alabama

Abstract

Although North American wood ducks (Aix sponsa) are well‐studied throughout their range, researchers know little about demographic and environmental factors influencing survival of ducklings and broods, which is necessary information for population management. We studied radiomarked female and duckling wood ducks that used nest boxes and palustrine wetlands at Noxubee National Wildlife Refuge (NNWR) in Mississippi, USA, in 1996–1999, and riverine wetlands of the Tennessee‐Tombigbee Rivers and Waterway (TTRW) system in Alabama in 1998–1999. We estimated survival of ducklings and broods and evaluated potentially important predictors of duckling survival, including age and body mass of brood‐rearing females, hatch date of ducklings, duckling mass, brood size at nest departure, inter‐day travel distance by ducklings, site and habitat use, and daily minimum air temperature and precipitation. At NNWR, survival of 300 radiomarked ducklings ranged from 0.15 (95% CI = 0.04‐0.27) to 0.24 (95% CI = 0.13‐0.38) and was 0.21 (95% CI = 0.15‐0.28) for 1996–1999. Our overall estimate of brood survival was 0.64 (n = 91; 95% CI = 0.54‐0.73). At TTRW, survival of 129 radiomarked ducklings was 0.29 in 1998 (95% CI = 0.20‐0.41) and 1999 (95% CI = 0.13‐0.45) and was 0.29 (95% CI = 0.20‐0.40) for 1998–1999. Our overall estimate of brood survival was 0.71 (n = 38; 95% CI = 0.56‐0.85). At NNWR, models that included all predictor variables best explained variation in duckling survival. Akaike weight (wi) for the best model was 0.81, suggesting it was superior to other models (<0.01 < wi < 0.18). We detected 4 competing models for duckling survival at TTRW. Inter‐day distance traveled by ducklings was important as this variable appeared in all 4 models; duckling survival was positively related to this variable. Patterns of habitat‐related survival were similar at both study areas. Ducklings in broods that used scrub‐shrub habitats disjunct from wetlands containing aggregations of nest boxes had greater survival probabilities than birds remaining in wetlands with such nest structures. Managers may increase local wood duck recruitment by promoting availability of suitable brood habitats (e.g., scrub‐shrub wetlands) without aggregations of nest boxes that may attract predators and by dispersing nest boxes amid or adjacent to these habitats. We did not determine an optimal density of nest boxes relative to local or regional population goals, which remains important research and conservation needs.

Survival and habitat selection of wood duck ducklings

“…Contrary to the southern breeding range, we did not find evidence of a relationship with hatch date or mass. Patterns in habitat selection were consistent with previous research that identified use of woody or dense vegetative cover (McGilvrey , Sousa and Farmer , Smith and Flake , Granfors and Flake , Davis et al ). Brood and duckling survival may limit recruitment at our northern study area and additional data collection is required to support life‐cycle analysis (Coluccy et al , Davis et al ).…”

“…We assumed complete brood and duckling loss upon the death of a female during the brood‐rearing period (Granfors ). We defined a successful brood as ≥1 duckling surviving to 30 days post‐hatch (Granfors , Davis et al ).…”

“…Wood ducks commonly use dense vegetative cover for foraging, loafing, predator avoidance, and thermoregulation (Hepp and Hair , Bellrose and Holm , Granfors and Flake , Baldassarre ). Ephemeral wetlands provide a food base (McGilvrey , Hepp and Hair , Drobney and Fredrickson , Davis et al ) and riparian areas provide movement corridors between a variety of habitat types necessary for wood duck ducklings (Hepp and Hair , Bellrose and Holm ).…”

Genetic introgression and the survival of Florida panther kittens

“…Rigorous estimates of survival rates and understanding factors influencing those rates are critical for discerning proximate and ultimate causes of dynamics, regulation, and persistence of populations (Newton 2004; Ozgul et al 2006) and for devising and implementing management interventions for species conservation (Davis et al 2007). Population dynamics of many vertebrate species are strongly influenced by changes in survival rates (Heppell et al 2000; Oli and Dobson 2003; Stahl and Oli 2006).…”

Nest and brood survival of Ring-necked Ducks in relation to anthropogenic development and wetland attributes

“…Brood survival of Ring-necked Ducks in Minnesota (0.235) was similar to other diving ducks in the boreal forest (e.g., 5 of 22 and 1 of 10 scaup broods to 30 days [Greater Scaup (Aythya marila) and Lesser Scaup combined] in each of 2 years; Walker and Lindberg 2005), but was low compared to dabbling ducks (Mallards: Talent et al 1983, Orthmeyer and Ball 1990, Stafford et al 2002Wood Ducks: Ball et al 1975, Davis et al 2007; and Gadwall [Mareca strepera]: Pietz et al 2003), and diving ducks in parkland habitats of Minnesota and Manitoba (Canvasbacks; Korschgen et al 1996b, Leonard et al 1996. Brood survival in Ring-necked Ducks has only been examined previously in Maine and was substantially higher there (77% to 45 days, n = 64; McAuley and Longcore 1988).…”