Abstracts

Presented by Edward B. Farley - Email: efarley@ducks.org

Wetland managers need to understand how wetland management techniques influence food availability for waterfowl to help meet regional conservation goals. However, there is an information deficit on ecological returns on post-construction management of restored wetlands. We assessed the response of vegetation (summer), invertebrates (summer), seeds and tubers (autumn), and waterfowl (autumn and spring) to three wetland hydrology regimes (full water drawdown, partial water drawdown, and passive) on thirty randomly selected wetlands in the Montezuma Wetlands Complex, 2016 - 2018. We detected 127% and 90% greater seed and tuber densities in full (3-year mean = 848.7126.0 [SE] kg/ha) and partial drawdowns (681.862.5 kg/ha) than passively managed wetlands (365.020.5 kg/ha), respectively. Results suggest seed and tuber densities in managed wetlands in the northeastern United States are comparable to or greater than other parts of North America and moist-soil management should be considered an important technique to meet regional Duck-Energy-Day goals. Partial drawdown wetlands had greater submerged aquatic vegetation densities (3-year mean = 1,754.4473.0 kg/ha) than passively managed wetlands (3-year mean = 1,201.1527.4 kg/ha) across all years of the study. Partial drawdowns (3-year mean = 1,489.39 macroinvertebrates/m2116.48) also had 243% greater summer density of macroinvertebrates than passive drawdowns (3-year mean = 785.97 macroinvertebrates/m250.94) during the brood rearing period. During fall migration, passive wetlands had 367% and 182% greater waterfowl density than full and partial drawdowns respectively. In spring, waterfowl abundance was 216% and 156% greater in full and partial drawdowns than passive wetlands, with diving duck use 153% greater in both full and partial drawdowns and dabbling duck use 335% and 225% greater than in passive wetlands, respectively. We think seasonal differences in waterfowl use result from dry autumn and wet spring flooding regimes. Results reinforce the need for varying management techniques on wetland complexes to meet waterfowl needs throughout their annual cycle.