Ice on the refuges and movement of radio-tagged wood ducks: Aaron Yetter’s blog

November 15th, 2019 – Aerial Waterfowl Inventory Blog We flew the waterfowl survey on Thursday, November 14th, 2019. Duck numbers on the Illinois River dropped 26% from last week, and we found significant areas of ice covering our refuges. I am sure many duck hunters were fearful of this following the Veteran’s Day snowstorm and ensuing record low temperatures on Tuesday, November 12th. We estimated 186,415 ducks on the Illinois River this week, which was 44% below the 10-yr average. On the bright side, we did pick up a few mallards (up 31%) from last week; however, they are still well below (down 35%) average for mid-November. The central Mississippi River fared much better when we observed over 525,000 ducks; most of them on the lower reaches of the river from Quincy, IL to Grafton, IL. I believe the large increase in duck numbers along this portion of the river this week was due to the central zone duck season opener in Missouri on November 9th. Ducks were scattered throughout the region and were forced into the refuges once duck season started. To illustrate the departure of ducks from the Illinois Valley, I decided to show some data from our radio-tagged wood ducks. This fall we had several wood ducks that were tagged with cellular transmitters and provide waypoints of locations at various times of the day. My colleague, Sam Klimas, provided the following illustrations of the movements from a few of the marked wood ducks. Individual locations of these birds indicated they move from diurnal to nocturnal roosts usually under 2 miles apart, and they developed a routine of using the same day and night habitats until disturbed or forced out by weather. The movie clips illustrate the daily movements of the birds (Forbes Biological Station Facebook Page). The second video shows the large scale movements of the ducks when weather forced the birds to migrate south. When they departed the IRV, these individuals made large movements to the south over hundreds of miles. One particular bird moved ~450 miles in a 7-hr period. These tagged individuals are greatly improving our understanding of when and where ducks migrate. For more information about the waterfowl survey, check out our webpage at www.bellrose.org. Stay tuned for more updates next week…….