Postbreeding Ecology of Wood Ducks in the Illinois River Valley

The wood duck (Aix sponsa) is the most abundant nesting duck species in Illinois and consistently rank second only to mallards (Anas platyrhynchos) in both Illinois and the Mississippi Flyway duck harvest. Much research on wood ducks has involved their breeding ecology. However, despite the consistent and maintained harvest of this species, relatively few studies have investigated the postbreeding ecology of the species, especially in Illinois. We captured and radiomarked female and male wood ducks during the postbreeding period in late July and August as part of a three year study. Capture locations were within the La Grange Pool of the Illinois River extending from near Pekin, IL (River Mile 157.7), IL, to the La Grange Lock and Dam (River Mile 80.2) near Meredosia, IL. We used standard radio-telemetry techniques to track wood ducks to determine diurnal and nocturnal habitat use, daily movements, survival rates, stopover duration, and proportional use of refuge and non-refuge sites. We documented 8,235 locations of radiomarked wood ducks. Preliminary analyses indicate that locations of wood ducks were primarily in forested (44%), emergent vegetation (35%), and aquatic bed (14%) wetland habitats. We documented 3,810 movements from diurnal to nocturnal locations and preliminary analyses indicate wood ducks moved 2,781 m (45 SE) between daytime habitats and night roosts.