Picture an airport terminal full of songbirds, all buying tickets for flights south.
They're migrants, of course, leaving town for the winter. It's a mixed flock, many species, no rush, no pushing. Fall migration lacks the nesting imperative of spring.
In line by order of departure, shorebirds are first, looking for June flights. Then, swallows, booking for July, followed as the weeks advance by flycatchers, vireos, thrushes, warblers, sparrows and blackbirds.
The latter species want flights in late September and October.
Some are taking short flights, no farther than Missouri for many bluebirds. Other species go as far as Brazil.
Backyard birds like chickadees, nuthatches, cardinals, woodpeckers and finches might change local territory in winter, but they don't line up at ticket counters.
Most of our songbirds are tropical birds, briefly coming north for less-competitive breeding opportunities, then returning to South or Central America.
But not all tropical bird species are migrants. Migration is the exception, not the rule. Of the approximate 10,500 bird species in the world, around 15% migrate.
In the U.S., 318 landbird species move to the neotropics in winter, according to Roger Pasquier, author of the book "Birds in Winter." (Neotropics are the "new" tropics, those discovered when the Western Hemisphere was first explored.)
Why do some birds choose migration while others don't? Ornithologists continue to search for an answer.
An interesting migrant that spends its breeding season with us is the broad-winged hawk. A woodland species, it can be seen in the metro area.
Many birds route their migration across the Gulf of Mexico. Broad-wings do not. They swing southwest into Mexico, following the twists of Central America, always over land as they head deep into South America.
The flight path is squeezed when the birds reach Veracruz, Mexico. Over a million broad-wings can be seen there during fall migration.
Hawk Ridge in Duluth is an excellent place to see broad-wings as they begin that long trip.
Actually, Hawk Ridge is an excellent place to see 20 common raptor and owl species early in their migration. That season runs from late August into November.
Timing depends on the bird. If raptors were to line up for air tickets, the queue would look something like this, August to November: osprey, harrier, kestrel, merlin, peregrine falcon, broad-winged hawk, Cooper's hawk, sharp-shinned hawk, red-tailed hawk, Northern goshawk, rough-legged hawk, and finally golden and bald eagles.
These birds will avoid flying over water when possible. If they reach the shoreline of Lake Superior they follow the shore into Duluth.
Broad-wings can be stars of the show. On the best days, clear, with wind from the northwest, you might see tens of thousands of this bird, best viewed from the Skyline Drive location known as Hawk Ridge.
The hawks form what are called kettles, dozens or hundreds of birds drifting south in tight circles high above the city. Other species fly close by the overlook at eye level.
Owls and turkey vultures, and many songbird species, also use this migration path.
Everyone interested in nature should visit Hawk Ridge at least once during migration season. The upcoming special event known as Hawk Weekend, Sept. 20-22, is a great time to be there.
Hawk Ridge Bird Observatory, the sponsor, offers spotters, guides, programs, field trips, hikes, birds in hand, a banquet and guest speaker. Details, and a map, are at hawkridge.org.
Mid-September days are peak for broad-wings. The record high count for this raptor was set Sept. 15, 2003 — over 101,000 hawks in one day.
Read Jim Williams' birding blog at startribune.com/wingnut.