the western great lakes bird and bat observatory lake michigan offshore waterfowl surveys bill...

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