Breeding latitude drives demographic rate variation in wood duck populations, informing banding strategies in eastern North America

Abstract

Sustainable game management requires effective monitoring of population trends and demography at a biologically relevant scale. As a commonly harvested species that uses forested wetlands throughout their annual cycle, wood ducks (Aix sponsa) are challenging to monitor using traditional abundance methods; thus, banding is critical for assessing vital rates. We used capture-mark-recovery data of wood ducks banded during the pre-season period from 2000–2022 to evaluate spatial variation in demographic rates and used the results to provide updated monitoring recommendations. We fit a dead-recovery model with Brownie parameterization within a Bayesian framework at varying spatial scales to characterize demographic rate variability. We identified significant latitudinal gradients in wood duck demography within the Atlantic and Mississippi flyways. Specifically, 3 latitudinal regions maximized inter-region variation and minimized intra-region variation in survival and harvest probabilities. Using simulations of varied band deployment across these latitudinal zones, we found that current deployment distribution was reasonably robust to latitudinal bias, but changing deployments in the future could lead to considerable bias in flyway-wide estimates of survival and harvest probability, which are used to set harvest regulations. We recommend revised banding goals and annual estimation of survival and harvest probabilities by latitudinal region to optimize wood duck harvest management and account for changes in band distribution over time.