(Betsy Bloom/Daily News photo) Red-eyed vireos, like this one hunting for insects, are among the songbird species now migrating through the region.

Now is the time to get out for the last glimpses of the songbirds that don’t stick around for winter. Their movement south already is in full swing.

Waves of warblers, vireos, swallows, flycatchers and other smaller species have begun showing up in Wisconsin, departing from the Upper Peninsula and farther north.

And if you can’t see them, you might be able to hear them — at night.

It’s the time of year when, as I leave the office in downtown Iron Mountain, the darkness above will have the faint sounds of twittering.

Phyllis Carlson of Quinnesec noticed the change as well.

“Go out on a starry nite in the Fall and LISTEN — you can hear birds as they migrate over,” she posted Sunday on Facebook. “Last nite over 859,000 flew over Dickinson Co. Fall migration is in full swing!”

She got that number from the Migration Dashboard on the BirdCast website, https://dashboard.birdcast.info/, a useful tool for monitoring the peaks of seasonal movements for migratory birds. It’s supported by the Cornell Lab of Ornithology, Colorado State University and the University of Massachusetts Amherst.

The dashboard showed Friday that an estimated 1,140,800 birds had passed through the county overnight, from just before 8 p.m. to about 6 a.m. It explained, “Birds usually begin to migrate 30 to 45 minutes after sunset, with the greatest number in flight two to three hours later.”

As of Friday, the site estimated about 9,423,200 birds had fully crossed the region, all of them headed south.

Most migrating birds do their traveling at night, according to the National Audubon Society, https://www.audubon.org. A September-October 2013 Audubon magazine article by T. Edward Nickens, “Listening to Migrating Birds at Night May Help Ensure Their Safety,” detailed the reasons why the birds favor that time period when they’d normally be least active.

“The stars and the moon aid night-flying birds’ navigation. Free of daytime thermals, the atmosphere is more stable, making it easier to maintain a steady course, especially for smaller birds such as warblers that might fly as slowly as 15 miles per hour. Cooler nighttime temperatures also help keep hard-working birds from overheating. And for birds that frequently wind up on the menu of hawks, cats, and other daytime predators, flying under cover of darkness can be a lifesaver,” Nickens wrote.

His article was on researchers developing recording methods to capture the sounds birds make during night flights, with the goal of better understanding the role these vocalizations play in nocturnal migration.

“While scientists aren’t certain about the reasons that migrating birds call when flying at night, there are some widely accepted theories. Research has shown that birds do it more frequently in rough weather and when navigating headwinds and crosswinds, so the calls likely help birds stick with their flocks. Communicating at night might also prevent fatal crashes. High call rates coincide with incidences of mass collisions with tall, lit structures such as high-rises and offshore energy structures. It may be that night flight signals serve as a warning to other birds about such perils,” Nickens wrote.

The full article can be read at https://www.audubon.org/magazine/september-october-2013/listening-migrating-birds-night-may.

BirdCast also has live bird migration maps as detected by U.S. weather surveillance radar network, produced by the Cornell Lab of Ornithology. Another map, this one done by Cornell and Colorado State, predicts which areas in the U.S. will see high migration activity in coming days.

So a number of online resources are available to know what kind of migratory movement is expected as the seasons shift.

Betsy Bloom can be reached at 906-774-2772, ext. 240, or bbloom@ironmountaindailynews.com.