Abstracts

Presented by Elizabeth S. Bonczek - Email: lizzi.bonczek@gmail.com

Mottled ducks (Anas fulvigula) are endemic to the Gulf Coast of the United States, and are non-migratory throughout their range. Because of this, they rely on coastal marsh and associated habitat to fulfill their needs across the annual cycle. The Louisiana mottled duck population has declined over the last decade and the 2018 Louisiana breeding survey was the lowest on record. This decline may go hand-in-hand with the high rate of wetland loss and degradation, and agricultural shifts from rice to other crops. As the landscape changes, it is crucial to identify the times of the year when mottled ducks are most vulnerable to mortality, and which habitat types they use to better inform land conservation. We used the GPS locations of mottled ducks tracked between September 2017 and August 2018 to quantify adult female survival and evaluate home range and space use. We captured mottled ducks during molt and outfitted them with GPS-GSM transmitters to collect locations every two hours. We used the Known Fate procedure in program MARK to examine temporal variation in survival in reference to biological seasons and hunting periods. Our best-fitting survival model parsed the year by first and second hunting season splits. Weekly survival was lowest during the first hunting split (0.981) and highest during the second split (1.000), with overall annual survival estimated at 54.8%. Additionally, we created seasonal home ranges using dynamic Brownian bridge movement models to examine habitat use over the breeding, molting, and pairing periods. Mottled ducks used a variety of habitats, including rice and freshwater marsh, and there was substantial variation among individuals. They less frequently used neighborhood ponds and forested wetlands, which are not habitats typically associated with mottled ducks in Louisiana. By understanding seasonal habitat use, wildlife managers can implement targeted conservation and management strategies for the benefit of this flagship coastal marsh species.