Short Wave

Migrating Birds Have a Big, Clear Problem

October 22, 2025

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  • Collisions with glass windows pose a massive, often invisible threat to migrating birds, resulting in an estimated billion bird deaths annually in the U.S. 
  • Effective solutions to prevent bird-window collisions exist, ranging from turning off nighttime lights to applying specific patterns of decals or treatments to glass, as demonstrated by a 95% reduction in strikes at Chicago's McCormick Place after treatment. 
  • Advocacy groups are leveraging data collected from citizen scientists (like Lights Out DC volunteers) to drive change, leading to new local building codes requiring bird-friendly construction in cities like Washington D.C., New York City, and San Francisco. 

Segments

Introduction and Listener Support
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(00:00:16)
  • Key Takeaway: Listeners are encouraged to support Short Wave by leaving ratings or reviews on their listening platform.
  • Summary: The host, Emily Kwong, asks listeners to leave a rating or review on their platform, noting this is a free and easy way to help new listeners find the show. She shares positive feedback from a listener named Ruthie. The introductory segment concludes by transitioning to the main episode content.
Bird Migration Dangers
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(00:01:08)
  • Key Takeaway: Migrating birds fly at night to avoid predators and utilize cooler, more stable air, but this exposes them to artificial lights and deadly glass collisions.
  • Summary: NPR science correspondent Nell Greenfield Boyce discusses the annual mass migration of hundreds of millions of birds occurring nightly. Birds navigate using the moon and stars, which can draw them toward artificial lights. Upon resting during the day, they encounter glass, which is a major hazard, causing an estimated billion U.S. bird deaths yearly.
Impact of Window Collisions
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(00:02:33)
  • Key Takeaway: Bird collisions with windows often result in fatal injuries like concussions or broken bones, even if the bird initially flies away.
  • Summary: Volunteers in cities like D.C., Chicago, and Dallas actively search sidewalks every morning for collision victims. A specific example involved an Acadian flycatcher that did not survive treatment after hitting an office building window. Birds can strike glass at speeds up to 30 miles per hour, leading to severe internal trauma.
Urban Collision Hotspots
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(00:06:16)
  • Key Takeaway: Bird collisions occur most frequently below the tree line, with one- to three-story buildings accounting for many deaths due to their sheer number, though specific architectural features create ‘death traps’ like skyways.
  • Summary: The problem is not limited to skyscrapers; most collisions happen low down when birds rest. Certain buildings with highly reflective or transparent glass funnel birds toward deadly atriums or skyways, such as the mirrored glass skyway observed in D.C. Volunteers document these deaths to build data sets for advocacy.
Solutions and Mitigation Strategies
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(00:09:08)
  • Key Takeaway: Effective window treatments require specific patterns of dots or lines covering the entire glass surface, rendering hawk decals ineffective for broad protection.
  • Summary: Solutions include turning off nighttime lights and applying bird-friendly window treatments based on years of research. Hawk decals only prevent birds from hitting the decal itself, not the whole window. Treatments must cover the glass with patterns of a certain size so birds perceive it as a solid barrier, not open sky or reflection.
McCormick Place Case Study
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(00:10:03)
  • Key Takeaway: Applying full-window dot patterns to Chicago’s McCormick Place convention center reduced bird collisions by 95% following a mass casualty event.
  • Summary: After nearly a thousand birds died crashing into McCormick Place, the center installed dot decals across its vast glass surfaces. This intervention, covering glass equivalent to two football fields, resulted in a 95% reduction in subsequent bird collisions. This event spurred collaboration among bird groups, architects, and researchers.
Collaborative Prevention Efforts
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(00:11:48)
  • Key Takeaway: The Bird Collision Prevention Alliance was formed to share science and create toolkits for various scenarios, focusing on local solutions rather than national policy.
  • Summary: The alliance brings together over 100 members, including federal agencies and bird groups, to work collaboratively on saving birds at scale. While they avoid national politics, they focus on local building codes, which are already being adopted in D.C., New York City, and San Francisco. Planning bird-friendly design from the start minimizes renovation costs.
Individual Home Action
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(00:14:46)
  • Key Takeaway: Homeowners should treat any window where a collision has been heard, and specifically target windows near bird feeders, baths, or fruit trees.
  • Summary: Listeners can take action by treating any window proven problematic by a previous ’thunk’ sound, as they may not witness all incidents. Treatment should also be applied to large, reflective windows or sliding doors near attractive bird features. Effective solutions range from DIY painting to commercially available products that prevent future strikes.