Millions of birds soar above the suburbs as spring migration peaks

This week, millions of birds will fly through the night skies above the Chicago area as they travel from their winter homes down South to their summer breeding grounds in Canada and northern states like Wisconsin and Minnesota.

With spring migration in full swing, hundreds of species such as the Baltimore Oriole and Nashville Warbler are following Illinois’ rivers and Lake Michigan to find their way. Free of daytime temperatures, the birds are further aided by the stars, moon and stable night atmosphere.

“It’s an extremely exciting time of year for birdwatchers,” said Tom Prestby, Audubon Great Lakes Conservation Manager. “Beginning middle of May is really when everything comes together, and we have the highest number of species around that we're going to have at any time in the calendar year.”

Spring migration is long and it comes in waves, starting in late February and March with waterfowl and goose migration. Next, short-distance migrants like Robins and Red-wing Blackbirds make their way up.

And finally, the reason May is so exciting to avid birdwatchers: the neotropical migrants come.

“Those neotropical songbirds that we all get really excited about like warblers, Scarlet Tanagers, orioles, grosbeaks, buntings — they're all in peak migration right now,” Prestby said.

While birds are migrating all across the country, Chicagoland gets a front-row seat given its position in one of the major migratory bird routes in North America, the Mississippi Flyway.

And while migrating birds can be seen in quite a few places in the Upper Midwest, Lake Michigan’s shoreline acts as a barrier and a guide for many migrants.

“They’ve already been using a ton of energy migrating. They do not want to cross that body of water. So cities like Chicago, Milwaukee, those larger cities along the Great Lakes and especially Lake Michigan since it's a north-south oriented lake — they basically use that shoreline as their guide north,” Prestby said. “Especially within a couple of miles of the lake, you get higher numbers of these migrants than you would in most other places in the Midwest.”

While spring migration serves as a wondrous natural phenomenon for many, it also represents the highest mortality risk these birds will face in their lifetime. And the birds’ greatest challenges are human-caused: loss of habitat, collisions with manmade structures and climate change.

As global warming makes false springs more likely — characterized by early onset spring followed by freezing temperatures — some birds are migrating earlier only to find themselves facing death and decreased food amid icy weather.

On the other hand, some birds that haven’t adapted to earlier springs can miss out on peak food resources like insect emergences and new plant growth, Prestby said. This is particularly true for long-distance migrants that rely on innate triggers to begin migration, such as length of daylight.

In the case of collisions, city lights are the prime culprit. Birds can become disoriented by bright artificial lights and skyglow, causing them to collide with buildings or windows.

To combat the threat, bird lovers and environmental organizations are promoting Audubon’s Lights Out program, which encourages home and building owners to turn off or dim their lights as much as possible during spring and fall migration seasons.

Property owners can also consider planting natives to help fill gaps in habitat — and to attract birds to their own lawns, Prestby said.

“You can bring birds to your own yard if you own property, or even if you don't and you just have a balcony or something similar,” he said. “Planting native shrubs or perennials or trees if you're able to is a huge, huge benefit to birds. They'll seek out native species as they're migrating because native species provide insects for them and they're aligned to match when these native species are in their blooming period.”

For people looking to birdwatch, Prestby recommended Audubon’s online tools including its Bird Migration Explorer and Illinois Coastal Stopover Tool.

Parks along Lake Michigan such as Montrose Park, Lincoln Park and Jackson Park get high numbers of birds, along with natural areas like Fort Sheridan in Lake Forest, Rollins Savanna in Grayslake and Illinois Beach State Park in Zion.

“You really can’t go wrong this time of year if you just get outside with your (binoculars), in the morning especially,” he added. “You can seek out large numbers of birds at some of those parks along the lake, but going to any kind of park or forest preserve or something like that basically until about Memorial Day is going to usually result in a really fun morning.”

• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.