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