Thousands upon thousands of birds are expected to cross over Illinois as part of their spring migrations in coming days.

Thursday night saw the highest migration totals of the season so far, but researchers at Cornell believe that Sunday and Monday nights could see even more avian traffic in the skies over the Chicago area, with hundreds of thousands of birds expected to traverse the area.

According to estimates from Birdcast, Sunday night and into Monday morning there could be “medium” activity for migrating birds, with thousands of birds per kilometer flying over the area.

Even more birds are expected to take flight Monday night and into Tuesday morning thanks to favorable weather conditions, with a “high” number of birds expected to take to the skies over the Chicago area.

According to estimates, up to 383 million birds could be in flight over the central United States during the peak of the migration overnight.

On Thursday night the Chicago area experienced its busiest night of the spring migration season so far, with more than 367,000 birds having been estimated to have passed over Cook County alone.

In all, more than 23,000,000 birds are believed to have crossed the state of Illinois so far during the spring migration.  

Among the primary birds expected to be flying through the area are American Redstarts, Magnolia Warblers, Baltimore Orioles and Indigo Buntings, according to researchers at the CornellLab.

As millions of birds continue visiting the Chicago area, here are some steps that residents can take to keep them safe.

When do birds typically migrate?

Peak migration for birds over the state of Illinois occurs in mid-to-late May, with hundreds of different species heading north for the summer breeding season.

Those migration flights for songbirds and other species typically take place in the overnight hours. According to experts, birds typically take flight 30-to-45 minutes after sunset, with the greatest number of birds in flight typically seen approximately two-to-three hours later.

When should residents turn lights off?

One of the best ways to help protect birds is to turn off lights during peak migration times.

According to Birdcast, the best time to turn off or dim exterior lights and interior lights is between the hours of 11 p.m. and 6 a.m., when most birds are active.

Bright lights can disorient and attract birds, making them vulnerable to collisions and to predators on the ground, according to the website.

Hundreds of millions of birds are killed each year in collisions with buildings, and residents and businesses are being asked to do their part to keep the creatures safe.

In addition to turning off unneeded exterior lights, residents and businesses are also asked to dim or turn off lights in lobbies, and to draw blinds to help keep light from escaping through windows.

Finally, exterior lights should be aimed downward and be well-shielded so that birds aren’t attracted to them.

Are there other steps?

Another key step in protecting birds is to bring pet cats inside during overnight hours.

According to the American Bird Conservancy, cats kill an estimated 2.4 billion birds in the United States every year, and during migration season those impacts can be even more devastating, as exhausted birds typically seek refuge in plants and trees to rest on their journeys, making them vulnerable to attack.

Since cats like to hunt at night, active migrating birds can be a target, leading to experts asking residents to keep animals inside when possible.