Food Selection of American Green-winged Teal During Spring Migration in Illinois

The Illinois River Valley (IRV) is an important region for non-breeding waterfowl, especially during spring migration as they replenish reserves to complete migration and prepare for the breeding season. Identification and management of preferred waterfowl food species can improve habitat quality and increase the body condition of waterfowl. American green-winged teal (Anas crecca; hereafter teal) specialize on natural foods, often feeding on small seeds and invertebrates in shallow water or mudflats. To identify food selection we experimentally collected 64 foraging teal and three benthic and nektonic core samples from each collection site during spring migration in the Alton, La Grange, and Peoria Pools of the Illinois River during February–April 2016–2017. We removed and sorted, dried, and weighed (± 0.1 mg) food items from the upper digestive tract (proventriculus and esophagus) of collected birds and core samples for comparison of use and availability, respectively. Further, we performed proximate analysis on teal carcasses to analyze body condition in relation to diet composition. Preliminary results suggest teal consumed 73.9% (CI95 = 65, 83%) plant material and 26.1% (CI95 = 17, 35%) invertebrates based on aggregate dry mass. In spring 2016, the most abundant foods in teal diets were seeds of smartweed (Polygonum spp.) and flat-sedge (Cyperus spp.) and aquatic worms (subclass Oligochaeta). Average food availability estimated from core samples was 308.9 kg/ha. and smartweed, duckweed (Lemna spp.), and aquatic worms were the most abundant food items at collection sites. Our study will present a novel look at food selection of an ecologically and economically important duck in Illinois and the Mississippi Flyway. Moreover, our results will provide a composition of vegetation to guide active wetland management resulting in increased food availability for spring migrating teal and other waterfowl species that forage in emergent wetlands.