Semester of Graduation

Summer 2025

Degree

Master of Renewable Natural Resources (SRNR)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Understanding variability in breeding origins of harvested waterfowl is important for effective population management and regional conservation. Band-recovery data are often used to estimate harvest derivation and inform resource allocation for cross-seasonal conservation. However, uneven spatial and temporal banding effort across species' breeding ranges may result in an incomplete understanding of summer origins and recruitment, particularly if portions of the breeding range are inaccessible. Analysis of stable-hydrogen isotope ratios in duck feathers (δ2Hf) provides an alternative method for identifying source origins of unmarked populations since environmental deuterium values follow a predictable latitudinal gradient across North America. I collected >1800 feather samples from cohorts of male and female adult and juvenile blue-winged teal (Spatula discors), gadwall (Mareca strepera), green-winged teal (Anas crecca carolinensis), lesser scaup (Aythya affinis), mallards (Anas platyrhynchos), and northern pintail (Anas acuta) harvested across Louisiana during the 2022–2023 waterfowl hunting season, and >2200 samples during the 2023–2024 season. In Arkansas, I collected >800 samples from green-winged teal and mallards in the 2022–2023 season, and >900 in the 2023–2024 season. In Chapter 1, I evaluated how δ2Hf and inferred geographic origins differed by sex, age, harvest region, and harvest date across two years for each species. While I found statistical differences in δ2Hf across each parameter, these differences were not large enough to detect interpretable differences in inferred origins. However, results revealed that high proportions of individuals likely originated from more northern geographies within their breeding range. In Chapter 2, I paired δ2Hf sampling with informative Bayesian priors (spatial relative abundance and proportional band returns), to compare the origins of waterfowl harvested in Louisiana to geographic areas of banding effort and band recovery. I found that while there is variation by species, many harvested individuals originated from latitudes underrepresented by long-term banding efforts. Together, my results suggest that while pre-season banding efforts are essential for informing population vital rates, they may not completely represent source origins if individuals move post-hatch or after molt prior to capture. Additionally, these findings improve our understanding of migratory connectivity and could aid strategic conservation initiatives targeting specific breeding geographies.

Date

6-30-2025

Committee Chair

Fowler, Drew N.

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Available for download on Tuesday, June 30, 2026

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