White-cheeked Pintail duckling and brood survival across wetland types at Humacao Nature Reserve, Puerto Rico
Duckling survival is an important influence on recruitment in several North American Anas species. White-cheeked Pintail ( Anas bahamensis ) breeding in Puerto Rico encounter a variety of wetland types that may influence duckling survival. We monitored fates of 92 radio-tagged ducklings in 31 broods in 5 wetland habitat types at Humacao Nature Reserve in southeastern Puerto Rico from 2000 to 2002. Wetlands included 2 separate coastal lagoon complexes, mangrove forest, and managed and unmanaged wetland impoundments containing herbaceous vegetation. We used known-fate models to estimate daily and interval survival rates of ducklings and broods. We conducted conservative and liberal analyses of survival because of uncertain fates of 36 ducklings. In the conservative analysis, the most parsimonious model for duckling survival contained wetland type and a positive influence of daily precipitation. In the liberal analysis, duckling survival also varied among wetlands, was positively influenced by daily precipitation, but negatively influenced by hatch date. Brood survival was also positively influenced by precipitation and female body mass. Managed wetland impoundments and shallowly flooded lagoon habitats containing ferns, interspersed cattail ( Typha dominguensis ), and other herbaceous cover promoted up to 3 times higher survival of ducklings over the course of a 30-day duckling period than we found in mangroves, more deeply flooded lagoons with predominately restricted shoreline cover, or unmanaged impoundments overgrown with vegetation. Broad confidence intervals for survival estimates among wetlands preclude unequivocal interpretation, but our results suggest that White-cheeked Pintail ducklings survive poorly in mangroves but benefit from appropriate management.