The Western Great Lakes Bird and Bat Observatory Lake Michigan Offshore Waterfowl Surveys

1. The Western Great Lakes Bird and Bat Observatory Lake Michigan Offshore Waterfowl Surveys Bill Mueller, WGLBBO

2. Offshore Lake Michigan Waterfowl Surveys To learn more about the distribution of waterfowl and waterbirds in western Lake Michigan’s open waters, offshore surveys were conducted during fall, winter, and spring of 2010-2011 – with a second round of surveys in 2012. We received a USFWS Coordinated Bird Monitoring Grantfor 2010-2011, and a second grant for 2012.

3. Study area: the western offshore waters of Lake Michigan, from central Door County, WI, to Chicago, IL (Surveying an area ~ 1-10 miles offshore)

4. Our Objective Determine a more complete picture of offshore spatial and temporal distribution of waterfowl and waterbirds in western Lake Michigan’s open waters. Long-tailed Duck was the most frequently found species.

5. Observations took place from mid-October 2010 through early May 2011, and again from February 2012 through late April 2012, utilizing a twin-engine, WDNR aircraft flown out of Wittman Regional Airport, Oshkosh, WI. A double-observer protocol was used on each flight; observers did not communicate during the flight. We searched transects using parallel bands of known width.

6. WI Department of Natural Resources aircraft - a twin-engine Cessna Skymaster

7. Surveys were conducted along transects oriented north-south and spaced 3.2 km (2 miles) apart. This spacing helped avoid double counting and allowed adequate coverage. The fixed-wing aircraft flew at ~95 miles/hr ground speed following the mapped transects in alternating directions. Surveys were flown at a 100 m (300 ft) aircraft altitude.

8. SURVEY BLOCK AND TRANSECTS

9. The time of each bird sighting was recorded; position was marked via on-board GPS. No observations were recorded in extremely rough water conditions (e.g., no more than small waves; no whitecaps) Sampling units were single birds or groups of birds.

10. Transect width (200 m) is established within a band with a declination in degrees from the horizon from 17-20.9° depending on altitude of the plane.  Each observer uses a clinometer to establish the correct vertical declination from the horizontal during flight, to enable the observer to maintain the correct transect width.  

11. Visibility • Sun Glare (direction with respect to front of plane) • Light conditions • Water surface (e.g., calm, small waves – no whitecaps, occasional whitecaps) • Observer fatigue

12. Observation condition rating (based upon and determined independently for each side of the plane/each observer)        1.        Poor visibility conditions         2.        Fair         3.        Good/Average         4.        Very Good         5.        Excellent

13. Species Max. Count Total Count Date & Date& % of TotalRange Long-tailed Duck 25,555:11/2 32,714: 47.6 Oct-May Red-breasted Merganser 9,311:1/20 20,538: 29.9 Oct-May Common Goldeneye 6,660:2/11 6,946: 9.6 Oct-May Bufflehead 429:4/29 1,447: 2.1 Oct-May Canvasback 1,030:11/2 1,036: 1.5 Oct-Nov Bonaparte’s Gull 442:5/4 442: 0.6 May Greater Scaup 401:11/2 434: 0.6 Nov Common Merganser 308:2/11 312: 0.5 Jan-Feb 8 MOST ABUNDANT SPECIES Other species: MALL, HOGR, TUSW, COLO, DCCO, GLGU, WWSC, GRYE

15. Door and Kewaunee counties

16. LTDU Sightings by Month

17. RBME Sightings by Month