Denver's top bird-killing buildings

One of the biggest threats to migratory birds is city skyscrapers — and city data shows the Wells Fargo building is Denver's deadliest.

Why it matters: It's estimated that between 365 and 988 million birds die each year in the U.S. from building strikes.

• Birds are critical to ecosystems as pollinators and pest controllers. They're also lovely to look at and listen to, which can draw people in and help foster an appreciation for nature.

Driving the news: This month marks the start of spring migration when more than 300 bird species move through the Mile High City.

• Denver is part of the Central Flyway, which birds use annually to fly from their breeding grounds in the north to their wintering grounds in the south.
• Many birds won't reach their destinations, however, because downtown's glow can confuse and lead them to urban areas, where they're more likely to crash into windows.

By the numbers: Over the last four years, the Wells Fargo building on Lincoln Street has proven to be Denver's biggest bird killer. So far, 17 deaths have been recorded on its premises — the most of any other downtown building.

• The second-deadliest appears to be the Internal Revenue Service building on North Broadway, with 14 collisions.

State of play: To curb the problem, volunteers with Lights Out Denver — part of a nationwide movement in large cities — will spend the next several months patrolling downtown in search of birds that have collided with buildings. Their findings are reported to a public database.

• The team's goal is to partner with the most problematic buildings to help make them safer, such as installing outside screens so birds can see them, Tim Luethke, who helps run the program, tells Axios Denver.

What they're saying: For businesses unwilling to spend money to make changes, Luethke says the cheapest and simplest solution for saving birds is "just turn off their lights during migration season," which runs through mid-June and again from mid-August to the end of September.

The big picture: Lights Out Denver has collected at least 110 birds across 59 species. 90% of them were found dead.

What we're watching: The birds! Luethke says some of the best places to spot rare migratory species near the city are at Denver Audubon, Belmar Park in Lakewood and in the Central Park area along Sand Creek.

• "Sand Creek has just a huge diversity of birds. I just saw a cinnamon teal out there, which is a really rare duck species. That's a great spot," he tells us.

How you can help: Residences account for an estimated 44% of fatal bird collisions in the U.S. Bird-proof your windows with products like Feather Friendly or CollidEscape, and check out other DIY tips.

• Monitor bird migration in real time using BirdCast, a forecasting tool created with the help of researchers at Colorado State University.
• Lights Out Denver also welcomes volunteers.