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F.4-3: Spatiotemporal Dynamics in Winter Harvest Distribution of Mallards Banded in Arkansas

Presented by Douglas C OSborne - Email: osborne@uamont.edu

Band encounter data has been used to draw inferences about dynamics in distribution patterns of mallards (Anas platyrhynchos) since the 1950s. Based on these data, others have documented shifts in wintering locations of mallards in the Pacific Flyway during the 1950s and Central Flyway during the 1960s. Despite well-known biases in band encounter data, inferences made about harvest distribution can be informative to management and policy personnel. We used encounter data from mallards banded in Arkansas during winter between the years 1950-2017 to describe short- and long-term patterns in the distribution of mallards. We used kernel density estimation to quantify the center of winter harvest distribution and found significant overlap between historical and present distributions. However, not all shifts were in a northernly direction; models suggest center of mallard harvest in September is now 3.5 degrees more southerly than in the 1960s. Inversely, center of mallard harvest in December and January are 1 degree and 0.5 degrees further north than historically. In the long term, it seems likely that extreme climate events are constricting migration behavior and constraining wintering habitat selection. In the short term, we observed extensive inter-annual variation in harvest distribution for Arkansas banded mallards. We present these data with the caveat that mallards banded in Arkansas may not be representative of the entire Mississippi Flyway population. A sample of mallards banded in other Mississippi Flyway states had a further northerly and easterly wintering distribution. However, because a large proportion of Mississippi Flyway mallards wintered in Arkansas historically, understanding distributional shifts may be important not only to local managers, but may help inform management throughout the flyway.
Session: Harvest (Wednesday, August 28, 15:30 to 16:50)