The Great Lakes almost never freeze over completely, although in the bitter
winters of 1976-77, 1977-78 and 1978-79, all of the lakes had close to or over
90 percent ice cover. In more recent winters, such as 1993-94 and 2002-2003,
much of the lakes were heavily iced, and we experienced here (and to our
north) an influx of Red-necked Grebes and several species of diving ducks. The
intense cold in the Midwest now could result this winter in a similar influx,
although it is too early to tell at the moment. And I should say that we don't
yet have evidence of a strong positive correlation of Great Lake icing and
grebe fallouts -- all of this is speculation based on two events in the last
decade. Data from events in the 1970s and 1930s are less complete.
Since 1999, information about ice cover on these lakes has been mapped in the
Great Lakes Surface Environmental Analysis (GLSEA), a digital map of the
Great Lakes surface water temperature and ice cover that is produced daily at
the
NOAA Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor,
Michigan through the NOAA CoastWatch program. The lake surface temperatures
are
derived from NOAA polar-orbiting satellite imagery obtained through the Great
Lakes CoastWatch program. The data on ice cover is provided by the National
Ice
Center (NIC) and updated at least twice a week. Check this out on the web at:
http://coastwatch.glerl.noaa.gov/cwdata2/lct/glsea.gif
As Virginia birders have learned over the years, influxes of birds from the
north tend to come in years of low prey/food availability in boreal birds' core
range, rather than because of unusually cold temperatures to the north. So
while we shouldn't expect most influxes of birds here to be driven by colder
weather, the freezing of freshwater bodies to the north of Virginia usually
does
produce a noticeable increase in waterfowl numbers on unfrozen water bodies
here.
The bitter cold, when prolonged in our state, takes its toll on our species
as well: Brant can be frozen out of the saltmarshes, as happened in the grim
winter of 1976-1977, which sent waterfowl southward onto the Delmarva Peninsula
in great numbers. Brant foraged *inland* during that winter on the Delmarva
Peninsula, feeding on the rocket launch pads at Wallops Island, on roadsides,
median strips, and even front lawns in downtown Chincoteague. Many Brant died
of starvation and/or exposure, whereas others were killed on the roads by
vehicles. If I recall correctly, Bill Williams found many long-dead Brant on
Rogue, Cobb, and Hog Islands well into summer of 1977. Documentation of these
kinds of events by birders is invaluable, and this listserv is a good place to
post information of this sort (also good to post observations on www.eBird.org
and send to local regional editors for VA/MD: Marshall Iliff at miliff@xxxxxxx
and Todd Day at BlkVulture@xxxxxxx). Waterfowl researchers are often very
interested in anecdotal information from the wintering grounds.
In general, watching the chat-lines from states to our north can be a good
way to prepare for what we might find here (see
http://www.birdingonthe.net/birdmail.html for links) -- a Northern Shrike at
Assateague and a Common Murre
just offshore in New Jersey last week are good examples of uncommon species
that
might turn up in Virginia or, in the case of the shrike, are likely already in
Virginia. A few Snowy Owls have been reported just over our borders as well.
Finally, colder weather drives birds into feeders that might not otherwise
use feeder: after a week's absence (during the record-breaking warm weather),
at
least three Baltimore Orioles (2 ads., 1 imm.) and the Yellow-breasted Chat
have returned to the feeders here at the house. Numbers of birds attending the
feeders have increased from roughly 25 birds per day to about 200 per day.
Ned Brinkley
Cape Charles, VA
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