Shoreline Numbers and Channel Surveys

Continuing the series of Lake Michigan shoreline counts from last fall, I completed six more sessions in December and early January. Despite lower waterfowl diversity during these months, good numbers of diving ducks continue to pass, generally in response to local weather, forage availability, and various disturbances. On December 2, I tallied 11,596 Long-tailed Ducks at Lake Harbor Park. This unusually large cluster was concentrated by pressure from duck hunters far offshore to the north and south.

Other highlights were a Red-throated Loon and 9 Horned Grebes on December 19, and a juvenile Black-legged Kittiwake on December 24 at the Muskegon State Park overlook.

Consistently cold temperatures, strong winds, and snowfall during December made additional forays difficult, but more significantly, the chilly conditions produced early freezing along Lake Michigan. By early January, overall ice cover was the greatest since the winter of 1993/94. As shallow water froze, various species of waterbirds moved to open channels or left Lake Michigan entirely.

Under such conditions, shoreline counts are unproductive, so I switch to surveys of Muskegon Lake Channel, although careful counts can be quite time-consuming and somewhat uncomfortable. High numbers there reflect the impact of ice coverage this winter.

On January 12, with pack ice extending 0.5 mile offshore, my counts included:

Canvasback - 3

Redhead - 26

Greater Scaup - 547

Lesser Scaup - 1

Surf Scoter - 1

White-winged Scoter - 28

Long-tailed Duck - 21

Bufflehead - 3

Common Goldeneye - 553

Common Merganser - 16

Red-breasted Merganser - 48

The various species of divers forage at different distances from shore. Common Mergansers and Buffleheads not only stay very close, but they actually prefer inland waters. Common Goldeneye remain within one mile of shore, and Red-breasted Mergansers range only moderately further. White-winged Scoters and Greater Scaup forage further yet, and the most distant rafts consist solely of Long-tailed Ducks. These patterns relate to diving ability. The Long-tailed Duck dives deeper than all other local waterfowl and is surpassed only by the Common Loon. A scientific paper from 1947 reported that Long-tailed Ducks were occasionally caught in gill nets in Lake Michigan more than 200 feet below the surface!

Today, January 29, I conducted another survey at the channel. This time, pack ice extended three miles offshore, and according to the ice cover estimates provided by the National Weather Service, Lake Michigan was 45% covered with ice, and drift ice extended about nine miles from shore. At the limit of pack ice, Lake Michigan is approximately 100 feet deep, and this would preclude benthic foraging by all but the most persistent ducks. Still, I was amazed by some of the numbers:

Canvasback - 4
Redhead - 35

Greater Scaup - 2,258

Surf Scoter - 2

White-winged Scoter - 463

Long-tailed Duck - 3,137

Bufflehead - 1

Common Goldeneye - 912

Common Merganser - 6

Red-breasted Merganser - 18

I have never before seen so many Long-tailed Ducks in the channel. I did not find any Lesser Scaup, but I could have missed a few among the Greaters. Still, after painstakingly counting and observing them, I am certain that no more than 2% were Lessers. Both Surf Scoters were adult males, which are the least common age/sex cohort in this area. The White-winged Scoter total was astounding; without a doubt this is the most ever recorded in Muskegon County.

- Brian Johnson