Flights of Fall
Billions of birds fly through Minnesota on their way to their winter grounds.
By Michael D. Faw
Rivers of red-winged blackbirds were winging past as I stood on a grassy hilltop near Chaska. The fall evening provided perfect migration conditions with favorable winds and clear skies. Flocks of migrating birds were on their way, sometimes flying high and sometimes gliding by so low and close it seemed as if I could reach up and touch them. Every bird was on a winged mission--migrating south in search of abundant food and wintering grounds with resting sites, in places with milder climates and longer days.
Minnesota sits in the path of many avian flyways, and migratory birds pass over the state in great numbers each fall. The Mississippi Flyway is used by almost every waterfowl species leaving central Canada and heading south toward the tier of states along the Gulf Coast. Some birds, such as tundra swans, wing across Minnesota as they travel southeast from Alaska to the Eastern Seaboard and coast of North Carolina. Lake Superior--an open-water obstacle for many bird species--funnels raptors and warblers over Minnesota.
While some eagles and hawks passing through Minnesota spend the winter as close as Iowa, other hawks and birds such as pelicans and sandhill cranes fly to Texas. Robins and grackles stop short of the Gulf of Mexico and winter in Gulf Coast states.
Many of Minnesota's woodland warblers--common here in the summer--cross the Gulf of Mexico and continue on to Mexico, the Caribbean, and Central or South America. The ruby-throated hummingbirds you spot here in summer spend the winter in Costa Rica or the surrounding countries. For sandpipers, terns, and turnstones, the journey begins in Canada or Alaska and ends in South America.
Mass Migration. When birds are migrating, it's as if there's a marathon underway with skies full of fliers rushing to cover the distance. Red-winged blackbirds fly in massive, undulating waves that seem to span the horizon. Large Vs of Canada geese, clouds of snow geese, and lines of cormorants and American white pelicans pepper the sunlit sky.
Sometimes large numbers of migrating birds show up unexpectedly. During a few hours, bird-banding stations normally capture a handful of birds in mist nets. But near Nisswa last September, bander Mark Newstrom and his crew caught 37 migrating birds in an hour. Favorable winds and weather had triggered the flight of songbirds, including Tennessee warblers, chestnut-sided warblers, golden-winged warblers, black-and-white warblers, American redstarts, red-breasted nuthatches, and red-eyed and yellow-throated vireos.
"We were nearly overwhelmed with birds," said Newstrom, who has been banding birds for more than a decade. "The nets were full, and we had to scramble to process them. I'd never seen anything like it."
The captured birds left the station wearing metal leg bands, which might someday provide clues about routes and final destinations as people find and report banded birds.
Hawk Ridge. One day last fall, a record 102,329 raptors passed over Hawk Ridge Nature Reserve in Duluth, drawing national attention. The astronomical total on Sept. 15 included more than 101,000 broad-winged hawks, 82 American kestrels, 31 bald eagles, as well as turkey vultures and other hawks. Normally about 140,000 birds pass by Hawk Ridge in a few months.
"It was as if the floodgate had opened and released a flood of birds," said Hawk Ridge naturalist Debbie Waters. After two nights of cold, stormy weather that had stalled birds in the forests north of Duluth, the unfavorable weather pattern broke that morning. The wind blew from the north, the sun heated the air, and the hawks soared.
Hawk Ridge, one of the nation's top spots for viewing migratory hawks and songbirds, has attracted visitors from all 50 states and 40 countries. From Labor Day through October, visitors come for the spectacular views of Lake Superior and breathtaking glimpses of towering kettles (groups) of raptors spiraling upward as far as the eye can see.
For many years renowned hawk counter Frank Nicoletti has turned his eye to the sky and counted raptors there. Other highly skilled spotters, such as Tim Smart and Dave Carman, also use binoculars, spotting scopes, and hand-held click-counters to identify and count passing birds by size, shape, color, and flight pattern. Across a nearby ridge, volunteers and licensed bird banders work from an enclosed blind to capture raptors in nets and band them. Large crowds gather to observe the captured birds and help release them. Hawk Ridge staff and volunteers answer many questions as the crowds watch birds overhead and study the educational displays and literature.
Logistics. Once airborne, some birds glide slowly, and some move quickly-such as the common loon, which clips along at 70 miles per hour while migrating.
Birds try to reserve energy and body fat when they undertake migration. Soaring hawks glide on the wind to expend little effort. By flying in large V formations, Canada geese and tundra swans achieve aerodynamic efficiencies. Air passing over and under one bird's wings creates easy flying for the following birds.
Some birds follow ridges and shorelines that produce favorable breezes and air drafts to help the birds fly efficiently and reserve stored body fat. Crossing large bodies of water such as Lake Superior can expose small songbirds to predatory raptors and place them in peril if they become exhausted because they have nowhere to land, rest, and refuel.
Daytime migrants such as hawks, swifts, and hummingbirds are strong fliers. The earth's magnetic field and landmarks such as rivers, mountains, and vegetation zones guide them on their way.
To help ensure survival during migration, many birds form partnerships with summer-time rivals for territory, food sources, and nest sites. They find safety in numbers by confusing predators with so many possible victims. Also, flocks of birds have the advantage of more eyes to spot danger and food.
Some species, such as sharp-shinned hawks, follow and feed on flocks of smaller migrating birds. Nighttime migration offers safety from hawks and other predators.
Night fliers such as thrushes, warblers, and orioles navigate by the earth's magnetic field and by the stars. Office buildings with reflective glass windows and, in foggy weather, the flashing lights on communications towers can disorient them.
Time to Fly. Most Minnesota birds migrate when fall arrives, but their departure times vary. Among the earliest species to leave Minnesota, sandpipers begin leaving the state in early July. Waterbirds such as terns begin leaving in August.
In early fall you can spot arrivals from Canada's tundra: Dunlins, phalaropes, buff-breasted sandpipers, and the occasional ruddy turnstone pause briefly and leave quickly. Warblers are on the move in September. Others, such as sparrows, bluebirds, and robins, depart in October or November. In some species-such as the common loon-adults leave first, and the young of the year migrate up to a month later as they build their strength and increase body fat reserves. Most mallards and Canada geese stay on Minnesota's waters until freeze up. Some birds, including cardinals, chickadees, nuthatches, ring-necked pheasants, wild turkeys, and ruffed grouse, never leave.
Sometimes migratory birds decide to stay in Minnesota for the winter. Aerated office-building ponds and industrial discharge pipes create year-round open-water habitat. Bird feeders have also become a topic of controversy as more robins, mourning doves, Canada geese, and mallards are lured from leaving by the abundant food supply.
Unexpected Moves. At times entire species--chickadees, for example--that normally endure the Minnesota winter take flight en masse. Food shortages, severe weather, or other factors can cause the mass movement. While an exodus might leave some places void of a certain species in winter, birdwatchers might see record numbers of those species in other parts of the state or region.
Just as poor weather might force birds to move, fair weather can encourage them to stay. During the 2001 Christmas Bird Count (a 24-hour tally of birds observed nationwide), birders at Lowry Nature Center near Victoria counted record numbers of cedar waxwings, robins, and many waterfowl species. Lack of snow, warm temperatures, and open lakes created tolerable conditions for many birds, and they lingered. Missing from the count were juncos and other more-northern species that normally winter in Minnesota.
Viewing Places. If you want to observe the fall migration action, you're in luck. Minnesota is dotted with state parks, wildlife management areas, and other public places that attract migrating birds.
At Gooseberry Falls State Park on the North Shore, naturalist Retta James-Gasser reports: "We have many different birds passing through the park, starting with common nighthawks in late August, and white-crowned sparrows following. More than 20 varieties of wood-warblers also pass through the park because they do not want to head out over Lake Superior."
Along with fall leaf color, Itasca State Park in north-central Minnesota offers glimpses of common loons pausing on waterways as they migrate to the East or Gulf coasts. Northern goshawks perch in trees on their way to southern Minnesota.
To the west, Blue Mounds State Park's grasslands attract hawks, falcons, and mountain bluebirds. At the Minnesota Valley National Wildlife Refuge's Louisville Swamp Unit near Shakopee, birds gather on staging grounds to eat and build up fat reserves. Flocks range from small eastern bluebirds to large Canada geese. Robins, blue-winged teal, and herons also pause here to rest and feed.
In the southeast, the sprawling Whitewater Wildlife Management Area near Elba has 12 impoundments and 8 wetlands that attract large migratory flocks, including pelicans, Canada geese, and mallards. Flocks of migrating warblers use the nearby brush and woods to rest and feed. Weaver Bottoms, along the Mississippi River near Winona, is another resting stop. A November 2003 survey tallied more than 453,900 ducks and geese there. Thousands of tundra swans can be spotted as they fly from lakes in Alaska and the Yukon territories to open grain fields in North Carolina, Virginia, and Maryland.
City parks and other stopovers along the Mississippi are good places to encounter birds, such as tundra swans and eagles, that stop along the bluffs near Lake Pepin. Because of its importance to migratory birds, the river corridor is known as the Mississippi Flyway.
Places to observe birds abound. But remember that fall migration can be a hectic time for all wild birds, and your window of opportunity to see many of the migratory species might be a few weeks, or just a few days.
Perils of Migration
- Never to complete the journey. An estimated 20 to 30 percent of birds that hatch each year die in migration.
- Bad weather. Early snow or ice storms that cover food sources cause starvation. Strong winds can push birds off course and into unfamiliar habitat or over large bodies of water, where they become too exhausted to continue.
- Cats and other predators. With or without bell collars, cats take large numbers of birds resting and refueling at feeders.
- Windows. By some estimates, more than 100 million songbirds collide with buildings each year in the United States, disoriented by window glass.
- Communications towers. Flashing lights atop towers in foggy weather can disorient birds and cause deadly collisions with the dozens of guy wires that hold the tower in place. The nationwide death toll from towers is estimated at many tens of thousands.
For reports on bird activity, call Minnesota Ornithologists' Union at 763-780-8890 or 800-657-3700. Or visit The Minnesota Ornithologists' Union.
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Michael D. Faw is a freelance writer from Iowa who enjoys birding in Minnesota and elsewhere.