Abstracts

Presented by Samuel T Klimas - Email: sklimas@illinois.edu

The Illinois River Valley is an important region for non-breeding waterfowl, especially during spring as migrating individuals replenish vital nutrients to complete migration and initiate nesting. Identification and management of preferred waterfowl forages helps ensure adequate body condition of spring migrating waterfowl which is essential for survival and subsequent nest success. Green-winged teal (Anas crecca; hereafter teal) specialize on natural plant and animal foods in shallow wetland environments which may be limiting during spring migration. To identify diet selection, we collected 166 foraging teal and three benthic and nektonic core samples from wetlands in the Alton, La Grange, and Peoria reaches of the Illinois River during FebruaryApril 20162018. 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 with a multivariate analysis of variance. Seeds of early successional vegetation occurred in all teal diets, while invertebrates and vegetative material occurred in 67.4% and 25.8%, respectively. Teal consumed 85.8% (CI95 = 81.290.3%) plant material and 14.2% (CI95 = 9.618.7%) invertebrates based on aggregate dry biomass. We failed to find support for selection of plant and animal foods (t140 -0.7, P = 0.5), but at the taxa level teal selected Cyperus spp., Ammannia spp., Leptochloa spp., and Potamoageton spp. but avoided Amaranthus spp., Ipomea spp., Echinochloa spp., and Oligocheta. We found no support for a difference in selection ratios between sexes (F1,139 = 0.7, P = 0.7). Teal require a variety of early successional plant seeds and associated invertebrates which can be promoted by active moist-soil management at stopover locations. Managers should ensure shallowly flooded wetlands are available with diverse plant and invertebrate communities.