As of mid-November 2010, we have: 1) completed 1 season of field work related to this project, including conducting 7 foraging trials in 3 different wetlands; 2) processed 185 foraging-trial samples, and; 3) compiled preliminary results. Spring migration was compressed in 2010 due to a late thaw, which may have led to faster turnover (i.e., shorter duration of stay) of ducks at our study sites, thereby influencing their willingness to forage in trial plots. Duck use of trial plots was greater early in migration than late, corresponding in decreased seed consumption (i.e., increased giving-up density [GUD]) over the course of spring. Herein, we report our activities, preliminary results, and potential modifications to the experimental design for the 2011 field season. 1) Experimentally estimate GUD (kg/ha) of migratory mallards and other dabbling ducks during Spring (e.g., late-February to mid-April) in moist-soil wetlands in central Illinois. We conducted 7 experimental trials at 3 wetland complexes in central Illinois during spring 2010. Our study sites included wetlands that were readily used by mallards (Anas platyrhynchos) and other dabbling ducks (Anas spp.), were accessible by all-terrain vehicle (i.e., to place and remove experimental foraging patches), and could be observed from a distance without disturbing the study plots. Thus, we conducted 3 trials at Spring Lake Bottoms State Fish and Wildlife Area (Illinois Department of Natural Resources) in Tazewell County, 3 trials at Sand Lake (privately owned) in Mason County, and 1 trial at The Emiquon Preserve (The Nature Conservancy) in Fulton County. We initiated trials 17 March (i.e., immediately after ice receded) and concluded 12 April, after most dabbling ducks had departed. Ice-out was considerably later than normal in 2010, which lead to a compressed spring migration period and 2 a relatively short amount of time to conduct the experiments. Individual trials lasted 6–21 days, depending on the amount of duck use that trial plots received or if they were clearly abandoned. 2) Evaluate if GUD of spring-migrating dabbling ducks in central Illinois varies with respect to initial seed density (kg/ha), seed size (e.g., large or small), predation risk (e.g., visual obstruction near foraging sites), substrate type (e.g., sand or clay), or environmental covariates (e.g., temperature).
|Name||INHS Technical Report 2010 (46)|