April is when serious spring bird migration begins.

Author and birding guide Kenn Kaufman has a new book about migration that will make a timely arrival — April. The title is "A Season on the Wind, Inside the World of Spring Migration."

Kaufman lives where spring songbird migration is as good as it can be in North America. His home is in northwestern Ohio, near the Lake Erie shoreline, a short drive from a patch of swampy woods known as Magee Marsh.

I would not have picked northwestern Ohio as a go-to birding hotspot, but I have learned it is special in the spring. One visit in mid-May proved that. All the superlatives Kaufman uses to describe this place are appropriate.

His book centers on the marsh and the stretch of Lake Erie shoreline that it adjoins. He discussion is broader, however. He visits the reasons and mechanics of migration, its glories and its problems.

He touches Minneapolis at one point, indirectly, when he talks about flyways, those paths though the air that birds are supposed to follow. Some do, he writes, and some don't.

That brings to mind one of the arguments against U.S. Bank stadium and the threat all of its glass is said to pose to birds moving north along the Mississippi flyway. That's a migration route that generally follows the river.

It's truer for waterfowl than for songbirds, Kaufman writes. Flyways for the latter are mostly imaginary, he says, irrelevant, references to them even misleading.

Rather, spring migration fills the sky with birds, horizon to horizon as you move from the Great Plains east.

Kaufman writes that "one piece of sky is much like another. Most of the time it's more beneficial for them (birds) to spread out, and they do," he says.

Birds move on a broad front, according to Kaufman, in the same general direction, "but not following particular routes.

Migration is influenced by weather and physical barriers terrain might create. In Minnesota think of Lake Superior.

Magee Marsh lies tight against the Lake Erie shore. Migrants everywhere move mostly during the night. Many of the birds arriving at the Erie shore at first light of day chose to stop, to rest and refuel before the challenge of a 30-mile crossing to Canada.

Birders call this a fallout, and pray to be there when it happens. Hundreds, thousands of birds come to ground as a mass. Magee Marsh has short willows, dogwoods, and other shrubby trees. That puts birds in some cases at eye level along a mile-long boardwalk that cuts through the marsh.

For the hundreds of birders that visit during the spring migration peak, the middle two weeks of May, Magee is all they could hope for.

I've been four feet from Black-throated Blue Warblers at Magee. This is a special species in Minnesota, small in number, isolated in location. It is safe to say there are few four-foot looks at this bird here.

In Minnesota, Park Point in Duluth can mimic Magee, however. Birds, facing a flight along the Lake Superior shore or over the water can drop in to rest and feed along the point.

A foggy day will ground the birds on the point, and keep them,perhaps thousands, in place until it clears. That is our version of Magee. Four-foot looks might be possible on the best days. Kaufman would feel right at home.

He also touches fall migration, explaining why the dangers and costs actually benefit the population of migrants that leave North America for southern warmth.

Most fall migrants are birds hatched just months before. Kaufman uses Blackpoll Warblers to make his point.

Blackpolls, nesting deep into the Canadian north, migrate east in the fall before they turn south. Their eventual flight path covers hundreds of miles over the Atlantic Ocean. If a bird is not fit, not strong enough to make the flight, it dies.

The survivors are the strongest, the best birds to pass genes to the next generation. Migration survivors keep Blackpolls on the landscape. Other warblers taking other routes south face other dangers offering the same benefit for the species.

Kaufman takes one chapter for harsh words about wind generation of electricity, and its cost to migrating birds. He understands the need for clean energy. His concern is with location of the generators. He has fought that battle on ground near his home.

"… wind turbines placed in the middle of essential stopover habitat are likely to kill disproportionate numbers of long-distant migrants," he writes of efforts in the Magee Marsh area. These migrants already are pushing the limits of survival as they make their mandatory return to nest.

The book will be on shelves and web sites April 2. Houghton Mifflin Harcourt is the publisher. The book is paper-backed, 288 pages, illustrated, price $26.