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 weekly aerial inventories of the Illinois (IRV; Hennepin south to Grafton) and central Mississippi river valleys (CMRV; Grafton north to New Boston) between September 2008 and January 2009. We considered fall 2008 habitat conditions for waterfowl in the IRV as“poor” due to growing-season flooding. Waterfowl habitat conditions in the CMRV were also below average due to spring and summer flooding. Peak abundance of total ducks inventoried was higher in the IRV and l ower in the CMRV in 2008 than 2007. In 2008, peak abundance of total ducks in the IRV was 221,300; this estimate was 16% higher than the 2007 peak (190,210) and 24% below the most recent 5-year average (2003─2007; hereafter, 5-year average) of 292,539. Total duck abundance in the CMRV was 345,745 (18% lower than 2007; 8% below the 5-year average). 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 captured and placed radio transmitters on 16 mallards (Anas platyrhynchos) (8 males, 8 females) at Chautauqua National Wildlife Refuge (NWR) near Havana, IL, in late November and early December 2008. Six birds departed LaGrange Pool of the IRV within 2 days post-capture and were not included in further analyses. The remaining 10 mallards were subsequently triangulated in wetland and upland habitats in Mason and Fulton counties. Frequently used areas included a power plant cooling lake (Duck Creek Power Station), gravel pit lakes and agricultural ditches in Fulton County, Rice Lake and Sanganois State Fish and Wildlife areas, Chautauqua NWR, The Nature Conservancy‟s Emiquon Preserve, and Quiver Creek. We estimated radio-marked mallards spent 10.8 days (SE = 3.0 days) in LaGrange Pool; however, we did not estimate duration of stay prior to capture. Home range size (95% minimum convex polygon) was variable and averaged 21,923 ac (SE = 7,530 ac). Radio-marked mallards were located on privately-owned wetlands more frequently (93% of locations) than publically-owned wetlands (7% of locations). Two of 16 birds (12.5%) were harvested by hunters (Illinois and Arkansas). We will continue to compile and analyze 2008 telemetry data throughout 2009-2010.
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