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The Western Great Lakes Bird and Bat Observatory
Lake Michigan Offshore Waterfowl Surveys
Bill Mueller, WGLBBO
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 Grant for 2010-2011, and a second grant for 2012.
Study area: the western offshore waters of Lake Michigan, from central Door County, WI, to Chicago, IL
(Surveying an area ~ 1-10 miles offshore)
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.
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.
WI Department of Natural Resources aircraft - a twin-engine Cessna Skymaster
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.
SURVEY BLOCK AND TRANSECTS
Figure 1. Survey Block Route
2 Miles from
Shore
4M
iles from Shore
6 Miles from
Shore
8M
iles from Shore
10 Miles from
Shore
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.
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.
Visibility o Sun Glare (direction with respect to front
of plane) o Light conditionso Water surface (e.g., calm, small waves –
no whitecaps, occasional whitecaps) o Observer fatigue
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
8 MOST ABUNDANT SPECIESSpecies Max. Count Total Count Date & Date & % of Total RangeLong-tailed Duck 25,555:11/2 32,714: 47.6 Oct-
MayRed-breasted Merganser 9,311:1/20 20,538: 29.9 Oct-MayCommon Goldeneye 6,660:2/11 6,946: 9.6 Oct-MayBufflehead 429:4/29 1,447: 2.1 Oct-
MayCanvasback 1,030:11/2 1,036: 1.5 Oct-
NovBonaparte’s Gull 442:5/4 442: 0.6 MayGreater Scaup 401:11/2 434: 0.6 NovCommon Merganser 308:2/11 312: 0.5 Jan-Feb
Other species: MALL, HOGR, TUSW, COLO, DCCO, GLGU, WWSC, GRYE
Door and Kewaunee counties
LTDU Sightings by Month
RBME Sightings by
Month
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