If you want to find eagles, the most important thing to know is they work only as hard as they have to.
When lakes up north start to freeze, eagles will head for the nearest open patch of water. In December, that's often on the northern stretches of the Mississippi River flyway, between Red Wing and Wabasha, Minn.
"They're still trying to decide where to spend the winter," says Pat Manthey of the Wisconsin Department of Natural Resources.
"We call them indeterminate migrators. They're not like the swallows of Capistrano that come back every year. Eagles only go as far as they need to go to find what they need."
If there's a cold snap in December, they'll head south, perhaps as far as Illinois. But some will stop below a dam or at the mouth of a river, and if the fishing is good, they'll stay.
Some discover commercial
fishing operations, such as the one in Ferryville, Wis., where they can
wait for cast-off fish.
Others find a field where hog or poultry farmers have discarded dead animals or ground them up and spread them with manure.
"(One year), I was sending people to a road between
Independence and Arcadia in Wisconsin because 200 to 300 eagles were
sitting in a farm field eating chicken guts," said naturalist MaryBeth Garrigan.
In the bluff country of northeast Iowa, the famous Decorah eagles spend the winter where they know they'll have a plentiful supply of food — right above a fish hatchery.
The pair is tracked as they travel, then shown via livestream after they return to Decorah in late fall to prepare the nest for eggs. Another pair, the Decorah North eagles, also are shown as they mate, incubate eggs and raise their eaglets.
For more web cams, see Wildlife reality show.
Other eagles spend the whole winter around Prairie du Sac, Wis., picking off fish stunned by a hydroelectric dam on the Wisconsin River. The local eagle council offers weekly bus tours.
But eventually, snow drives most eagles out of the fields and toward the Mississippi River.
"Usually, the birds get going in January, and then we'll see them for the next few weekends,'' said Terry Ingram of the Eagle Nature Foundation in Galena, Ill. , which offers bus tours along the Mississippi.
"Every week is different. Once a group of eagles was moving through when we were in Green Island, just south of Bellevue, Iowa, and we had 100 of them surrounding the bus.''
For a list of eagle-watching tours and festivals, see Where eagles land.
Eagle watchers on the Upper Mississippi actually welcome snow and severe cold, because it forces the eagles to congregate where there's open water.
"Eagles have no sense of smell, so they have to depend on their eyesight," Garrigan says. "Once it snows, they have to move to the river and depend on fishing."
Besides open water, they need a protected place to sleep, such as a valley with big, mature oak trees.
From there, they'll fly to
the river in the mornings, just after daybreak, then return to their
roosts until mid-afternoon, when they'll make another fishing trip to
stock up for the night.
When it's very cold, the eagles hunker down in
cottonwoods along the river, conserving energy. For the best chance of seeing them fly, go out early on a warm day after a cold snap, when they'll be hunting for food.
In February, eagles that had flown south start to move north, typically reaching Minnesota by March. And as the weather warms, eagles start to show courting behavior.
For the best luck finding eagles, go early in the day or
later in the afternoon. Dress warmly and bring binoculars. Along
rivers, look for dark blobs in cottonwood trees.
If you get close, don't startle the eagles by slamming car doors or making sudden movements, or they may return to their evening roosts with empty stomachs, wasting the energy they need to survive in the severe cold.
In Minnesota, the most reliable place to see eagles is Reads Landing, a tiny settlement across from the mouth of the Chippewa River just north of Wabasha.
Often, eagles fly overhead. There's also a nearby pullout on Minnesota 61 at Camp Lacupolis.
The National Eagle Center in Wabasha is a guaranteed place to see eagles, since four bald eagles and a golden eagle live there. Try to go during a feeding. The riverside center also has scopes for visitors to use.
It offers viewing maps of both the Wisconsin side of the river and the Minnesota side.
It also lists a weekly count of wintering eagles in the area, including Reads Landing and, across the river, Alma and Buffalo City.
For more, see All eyes on Wabasha.
Farther down Minnesota 61, past its junction with I-90, the rest stop/picnic area at Dresbach is a good place to spot eagles.
It's right across the river from Nelson Park at the northern tip of French Island in La Crosse, Wis., where there's a waterfowl viewing platform.
To get to Nelson Park, take Wisconsin 35-53 to the Oktoberfest grounds and turn west on Clinton Street. Go to Bainbridge Street and turn right. Take a left on Goodard Street, which turns into Lakeshore Drive. Follow it to the park.
In south-central Wisconsin, the dam on the Wisconsin River at Prairie du Sac is a good place to see eagles. Hydroelectric turbines stun the fish going through, making them easy pickings for eagles, and valleys amid the bluffs provide sheltered roosts.
Dams on the Mississippi River always are good places to look because they keep patches of water open all winter. There are 12 locks and dams between Minneapolis and Guttenberg, Iowa.
In Alma, Wis., across from Wabasha, the dam is right downtown, and eagles are easily seen from a platform. At the dam in Genoa, Wis., eagles gather to feed on shad cast off by ice fishermen.
Prairie du Sac and towns along the Upper Mississippi hold eagle-watching events and tours from early January through March.
In winter, sloughs that are buggy and wet in summer are easily navigated by snowshoe.
For information on a winter eagle-watching excursion between Wabasha, Minn., and Genoa, Wis., see Open sesame on the sloughs.
Farther south, look for eagles below Lock and Dam 13 in Fulton, Ill.
On the Illinois River, you can spot eagles from the Illinois Waterway Visitor Center across from Starved Rock State Park, where you can make a detour to see some of the park's spectacular frozen waterfalls and canyons.