Hundreds of millions of birds are migrating through the U.S. this weekend. (hollandevens / Pixabay)

Hundreds of millions of birds are currently on the move every night across North America as they wing their way south during fall migration. Chicago is under a high alert Sunday, with a massive number of birds expected to pass overhead.

Dead sparrows collected following collisions in Washington, D.C., which, unlike Chicago, isn't situated in a migratory flyway and there are no buildings taller than 10 stories high. (USGS Bee Inventory and Monitoring Lab)

Robyn Detterlines March Chicago Collision Bird Migration Madness tournament may be a product of her own imagination, but the stakes are very real for birds when it comes to navigating their way safely through Chicago.

One of Carvana's auto vending machines. (Courtesy of Carvana)

In response to concerns about putting a see-through glass tower in the path of migrating birds, Carvana revised its plan to incorporate bird-friendly components. Critics called the proposed mitigations “woefully inadequate.” 

One of Carvana's auto vending machines. (Courtesy of Carvana)

A 140-foot-tall transparent structure that’s brightly illuminated 24/7, located across the street from Harms Woods nature preserve, along a key migratory greenway, is a triple threat to birds, environmentalists say.

The notch in this sandhill crane's beak was caused by a plastic bottle cap, which became caught and kept the bird from being able to eat. (Willowbrook Wildlife Center / Facebook)

The U.S. needs a national strategy to deal with its plastic waste problem, which the country produces at a greater rate than the entire European Union combined, according to a new report. Interventions can’t come soon enough for wildlife.

The Thompson Center’s glass facade wouldn’t pass muster today under a new law requiring bird-friendly design for state buildings. (WTTW News)

Nearly 600 million birds are killed annually in North America due to collisions with buildings. A new Illinois law mandates bird-friendly design for state buildings.

A baby gull. (Elien Said / Pixabay)

Bird monitors said the gull colony is probably stressed in some way, either from lack of food, not enough room on the roof or extreme heat.

An American woodcock is being treated for injuries after colliding with a building in Chicago. (Courtesy Willowbrook Wildlife Center)

An American woodcock, one of the earliest migratory arrivals in Chicago, is recovering from a head wound and broken clavicle after colliding with a building in Chicago.

Migrating birds frequently are injured or stunned colliding with buildings in Chicago. (Courtesy of Chicago Bird Collision Monitors)

Chicago Bird Collision Monitors is recruiting volunteers to help rescue birds injured or stunned while navigating their way through downtown’s maze of confusing lights and glass buildings.

Since 2003, a group called the Chicago Bird Collision Monitors has made it their mission to collect birds that have been killed or injured after striking buildings and other structures.