Our Shared Environment Warbler season has arrived in Naperville

Late, late at night, when all is very still outside, you can still hear the ceaseless thrum-hum of tires on the highways -- I-88, Route 59, Ogden Avenue, 75th Street -- as people go about their business around and through Naperville.

What you can't hear are the thousands, perhaps hundreds of thousands, of warblers moving silently through Naperville's night sky on their migratory path to winter feeding grounds in Florida, Mexico, Central America and the West Indies.

Why at night? The darkness relieves some of the threat of predation for these tiny songbirds. The cooler night air helps avoid overheating on a journey spanning thousands of miles.

But wait until morning.

In the morning, warblers take a break from their prodigious journey from the northern U.S. and southern Canada, swooping into heavily wooded, densely shrubbed areas in and around Naperville. And when they do, they're hungry, needing to refuel before continuing the migration.

Warblers feed largely on insects and their larvae. This accounts, at least in part, for their proclivity for thick woods, hedges and shrubs. Go where the bugs are, eat hearty, rest a bit and continue the trek.

In general, you won't find warblers in our area during the summer (although there's always the exception when a couple of warblers don't read the book). The breeding and nesting ranges for most species are farther to the north and northeast, well into Canada. But twice a year they move through our neighborhood.

"Blackwell Forest Preserve, Herrick Lake, the Morton Arboretum and Green Valley are all great places to see warblers in September," said Doug Higgins, Naperville resident and avid bird watcher. "If you see a little bird in tree foliage or dense cover flitting from branch to branch every couple of seconds, chances are it is a warbler."

What kind of warbler is another matter. More than half of the 115 or so known species are in North America and they migrate through the Great Lakes region twice each year, in May and September. They display a range of colors: yellow, orange, red, blue, gray and brown. But from a distance, even the most brightly colored warblers look like LBJs -- shorthand among the birding intelligentsia for "little brown jobs."

"Without binoculars, however," said Higgins, "it is nearly impossible to clearly identify warblers because of their constant movement and habit of staying in tree foliage or dense cover."

On any given September day, the warblers' Naperville sojourn can be heavily influenced by prevailing weather patterns. Like airliners, migrating birds are helped or hindered by wind direction.

"The day after a front moves through," Higgins said, "you can expect to find a whole new batch of birds in our neighboring habitats."

Traveling with the front, birds can cover twice as much territory in a day. Conversely, a head wind will keep a flock of warblers in one locale until the wind direction changes.

The time for Naperville bird fanciers to see these little guys is right now and for the next week or two. After that they'll be vacationing in Mexico while we dust off the snow shovels.

Go out early, between 7 and 8 a.m. This is when the warblers have just finished the night's flight and are very active in search of food. Look for action in the high tree tops or dense underbrush.

You might also look for other people doing much the same thing, but armed with binoculars or long-lensed cameras. Look where they're looking; follow their lines of sight.

Likely you're in the company of birders who can help in first spotting, then identifying, a warbler. After all, who else would be out in the woods so soon after sunrise, when most of Naperville is queuing up at the nearest coffee shop?

You may find it a challenge to see that first warbler. You may find it a thrill to identify the second and the third. You may start a list (because that's what birders do). You may enjoy sharing a word with other bird watchers.

Or you may simply enjoy being outside, in a natural setting, sharing our environment with warblers, whoever and whatever. Certainly, it is worth a try.

Contact Rick Johnson at  johnson.rick5@gmail.com