Degree

Doctor of Renewable Natural Resources (PRNR)

Department

Renewable Natural Resources

Document Type

Dissertation

Abstract

Resident female wood ducks (Aix sponsa) in the southeastern United States are managed through nest box programs, with the goal of enhancing local hunting opportunities. Historically, hooded mergansers (Lophodytes cucullatus) were the only other cavity-nesting waterfowl species in the southeastern United States known to use these nest boxes. However, the recent northward range expansion of black-bellied whistling-ducks (Dendrocygna autumnalis) has extended into the range of wood ducks and mergansers. All three species are brood parasites, potentially using one another as hosts for their parasitic eggs and impacting their reproductive output. My research evaluated the nest box program administered by the Louisiana Department of Wildlife and Fisheries, focusing on the breeding ecology of cavity-nesting ducks and interspecific brood parasitism. Additionally, I analyzed a 14-year dataset for females banded from nest boxes to assess the impact of increasing the daily bag limit from 2 to 3 on wood duck survival and harvest rates. I monitored around 300 nest boxes weekly in Louisiana from 2020–2023, collecting data from February 1–July 31. I monitored individual eggs and nests, assigned fates, captured and banded incubating females, and marked ducklings. Trail cameras were placed inside a subset of nest boxes to collect videos. Among 261 black-bellied whistling-duck nests, I found nesting from late-March through late-July. About 7% of their nests were parasitized, primarily by wood ducks, with hooded mergansers as infrequent parasites. Black-bellied whistling-ducks hatched large clutches with varying compositions. I also monitored 1,206 wood duck nests; hooded mergansers and black-bellied whistling-ducks parasitized ~20% of nests. Parasitism by hooded mergansers reduced wood duck nest survival, but interspecific brood parasitism did not affect duckling recruitment. Wood duck egg survival decreased when in a clutch with hooded merganser eggs. Hooded mergansers had a more pronounced negative influence on wood duck productivity than black-bellied whistling-ducks. Red-bellied woodpeckers (Melanerpes carolinus) partially depredated wood duck clutches, reducing the number of wood duck eggs hatching at some sites. An analysis outside the breeding season revealed that increasing the daily bag limit did not affect the survival or harvest rates of box-nesting wood ducks. Future research should monitor black-bellied whistling-duck nesting chronology, as early-initiated wood duck nests are the most productive.

Date

10-30-2023

Committee Chair

Ringelman, Kevin M.

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