Study 107: AERIAL INVENTORIES OF WATERFOWL IN ILLINOIS Job 107.1: Inventories of waterfowl along the Illinois and central Mississippi rivers during fall and winter. Objectives: 1) Inventory waterfowl and American coots along the Illinois and central Mississippi rivers during fall migration using light aircraft. 2) Compute use-days and peak abundances for observed species. 3) Provide general inference regarding the distribution of waterfowl in space and time. 4) Compare these data to recent and long-term averages. 5) Summarize and distribute these data for parties of interest. We completed 14 aerial inventories of the Illinois (IRV; Hennepin south to Grafton) and central Mississippi river valleys (CMRV; Grafton north to New Boston) between September 2009 and January 2010. Habitat conditions for waterfowl in the IRV were poor due to flooding of wetlands during the growing season. Similarly, waterfowl habitat conditions in the CMRV were above average in early September, but extensive flooding along the lower CMRV in late October likely reduced the quality of waterfowl foraging habitat in this region. Peak abundance of ducks inventoried was higher in the IRV and CMRV in 2009 than 2008. In 2009, peak abundance of total ducks in the IRV was 226,950; this estimate was 3% higher than the 2008 peak (221,300), but 19% below the most recent 5-year average (2004–2008; hereafter, 5-year average) of 278,473. Total duck abundance in the CMRV was 530,250 (53% higher than 2008; 41% above the 5-year average). 3 Study 108: ECOLOGY OF FALL-MIGRATING MALLARDS IN THE ILLINOIS RIVER VALLEY Job 108.1: Ecology of fall-migrating mallards in the Illinois River valley. Objectives: 1) Document daily movements of mallards in the IRV and identify factors affecting inter-wetland movements. 2) Describe diurnal and nocturnal habitat use by marked individuals and identify factors associated with wetland habitat use. 3) Investigate patterns and length of foraging flights from rest areas. 4) Estimate survival rates and cause-specific mortality. 5) Determine number of days radio-marked mallards remain in the IRV after transmitter attachment, and if possible, determine stopover duration. 6) Evaluate proportional use of refuge and non-refuge sites. We radio-marked 71 mallards (Anas platyrhynchos) (41 females, 30 males) at The Nature Conservancy’s (TNC) Emiquon Preserve in Fulton County (near Havana, IL) during fall 2009. We estimated the average minimum daily movement of mallards in LaGrange Pool of the Illinois River was 4,374 ± 253 m. Our radio-marked birds stayed 29 ± 3 days in the IRV, and males (32 ± 4 days) stayed longer than females (26 ± 4 days). Mallards used open water wetland habitats most frequently (50.8%) followed by herbaceous wetland (15.9%), woody wetland (13.4%), andcorn fields (10.1%). Mallards were found on privately-owned lands for the majority (74.1%) of locations. Apparent survival during stopover in the IRV was 70.4%, and most mortality was attributed to hunting.
|Name||INHS Technical Report 2010 (35)|