Cooperative Fish and Wildlife Research Units Program: Mississippi
Education, Research and Technical Assistance for Managing Our Natural Resources

For dabbling ducks in North America, duckling survival is one important parameter in recruitment, and survival may be influenced by wetland quality and availability, and other extrinsic factors. The Neotropical White-cheeked Pintail (Anas bahamensis) is widely distributed across the Caribbean islands and South America, and classified as threatened in Puerto Rico and a species of Least Concern across most of its range. Broods of White-cheeked pintail encounter diverse wetland types throughout their range, including managed and unmanaged (e.g., lagoons, flooded forest) habitats. Understanding how wetland use, and other extrinsic and intrinsic factors during brood rearing might influence ducking survival is an important process toward identifying potential bottlenecks to species’ recruitment. Therefore, we monitored fates of 92 radio-tagged White-cheeked Pintail ducklings in 31 broods from 2000 to 2002 at the Humacao Nature Reserve (Humacao) in southeastern Puerto Rico. We used known-fate models to estimate daily and interval survival rates of ducklings and broods. We conducted two primary analyses of duckling survival given the uncertain fate of 36 radio-tagged ducklings: 1) We conservatively assumed signal loss was independent of mortality and right-censored ducklings at signal loss; and 2) we liberally interpreted signal loss as entirely confounded with mortality and hence treated those as mortality events. In the conservative analysis, duckling survival varied among wetlands and was positively influenced by daily precipitation (β = 0.46 ± 0.28 [SE]). In the liberal analysis, duckling survival also varied among wetlands and was positively influenced by daily precipitation (β = 0.33 ± 0.20) and negatively influenced by hatch date (β = -0.01 ± 0.003). Estimates of 30-day duckling survival ranged from 0.02–0.60 and 0.00–0.16 in the conservative and liberal analyses, respectively. The derived 30-day estimate for brood survival was 0.22 (95% CI; 0.10-0.44). Palustrine emergent wetland habitats, particularly those managed for or otherwise containing herbaceous vegetation promoted greatest duckling survival at Humacao. We suggest emphasizing wetland management to sustain nesting and brood-rearing White-cheeked pintail at Humacao. Artificial floating nest structures have been used historically in some wetlands for breeding females, however we encourage judicious use of nest platforms as these may serve as predator traps for ducklings in some wetlands at Humacao.