Energetic Carrying Capacity of Riverine and Connected Wetlands of the Upper Illinois River for Fall-Migrating Waterfowl

Abstract

Abstract The Illinois River historically provided high-quality habitat for a variety of migratory birds but sedimentation, management for commercial navigation, and increasing hydrologic variability have contributed to reductions in aquatic vegetation and naturally occurring foods for waterfowl. Cover of aquatic vegetation within the Illinois River Valley (IRV) declined during the 1950s, and it has not recovered in its historical range. The Dresden and Starved Rock reaches of the Illinois River, unlike other reaches in the IRV, still retain aquatic macrophytes in the main channel and connected backwater wetlands. To determine energetic carrying capacity of seeds and tubers for waterfowl in the upper Illinois River, we collected benthic core samples from random locations throughout the Dresden and Starved Rock reaches in falls 2013–2014. All sampling locations (i.e., main channel and connected backwater wetlands) had low mean density of seeds and tubers (<175 kg/ha) and duck energy days (DED; <1200 DED/ha)...