Short Wave — Migrating Birds Have a Big, Clear Problem

Host: Emily Kwong (NPR)
Guest: Nell Greenfieldboyce (NPR Science Correspondent)
Date: October 22, 2025
Duration: ~15 minutes

Episode Overview

This episode explores a major but often unseen danger to migrating birds: collisions with glass windows and buildings. Hosts Emily Kwong and guest Nell Greenfieldboyce delve into bird migration patterns, how human-made environments (especially glass buildings) threaten these annual journeys, and what scientists, volunteers, and city planners are doing to help. The episode balances science, real-world stories, and hope, with actionable solutions for individuals and communities.

Key Discussion Points & Insights

1. The Hidden Crisis of Migrating Birds

• Birds on the Move: Every autumn, hundreds of millions of birds migrate at night, mostly unnoticed by humans.

  • “Like every night, hundreds of millions of them are taking to the air…this is happening in the dark at night while we're sleeping.” — Nell [01:47]

• Why Night Flights? Birds migrate at night for cooler air, fewer predators, and celestial navigation (moon and stars).

  • "They use the moon and the stars." — Nell [02:05]

2. The Deadly Attraction of Artificial Lights and Glass

• Birds are drawn off course toward urban lights, often encountering glass—the invisible killer.
  • “When they come down to rest and refuel in the morning, they can encounter something that they have not been prepared for by evolution, and that is glass.” — Nell [02:14]
• Estimated at least a billion birds die in the US each year from window collisions, especially spiking during migration seasons.
  • "Researchers estimate that every year in the US...collisions with windows take out at least a billion birds." — Nell [02:37]

3. On-the-Ground: Volunteers and Bird Rescue Work

• Volunteers in cities like Dallas, Chicago, Philadelphia, San Diego, and Washington, D.C. rise early to find injured or dead birds beneath buildings.
• Profile of Stephanie Halley, a D.C. volunteer who rescued a stunned Acadian flycatcher:
  • "This is a good sign, the fluttering, which means that...hopefully, he's just stunned.” — Stephanie (via Nell) [03:50]
• Unfortunately, most collision victims succumb to their injuries, often flying up to 30 mph into hard glass.

4. Urban vs. Suburban/Rural Hazards

• Glass collisions aren't just a skyscraper or city problem. Most strikes happen at low heights, such as at homes and low-rise buildings.
  • "Most collisions are happening down low. Like below the tree line…one to three story buildings like homes—that accounts for a lot of the bird deaths…” — Nell [06:32]

5. Deathtrap Architecture and Data-Driven Solutions

• Certain buildings (mirrored glass, atriums, skyways) are especially hazardous, dubbed the “walkway of death” by volunteers.
  • "We call this the walkway of death. So this is a very deadly spot." — D.C. volunteer [07:00]
• Groups like Lights Out DC document every collision, providing crucial data that informs solutions and helps push for change.

6. Fixes and Scientific Solutions

• Decals & Patterns: Contrary to popular belief, hawk stickers don’t work unless the ENTIRE window is treated. Effective solutions use closely-spaced dots or lines across glass to break up the illusion of open air.
  • “If you've got existing windows you want to treat, you need like a pattern of dots or lines that's a certain size, basically so the birds won't think they can fly through. And this is effective.” — Nell [09:41]
• Case Study: McCormick Place, Chicago
  • After 1,000 birds died in a single night, the convention center applied dotted window decals over their expansive glass exterior—reducing collisions by 95%.
    • "Data taken before and after shows that this actually reduced bird collisions there by 95%" — Nell [10:56]

7. Collaboration & Advocacy

• Inspired by events like the McCormick Place disaster, agencies (US Fish and Wildlife, bird conservation groups, architects) formed the Bird Collision Prevention Alliance—sharing research and toolkits, not lobbying for laws but focusing on scalable, science-driven action.

  • "So they formed this new group called the Bird Collision Prevention Alliance...meeting frequently and putting together toolkits for different scenarios." — Nell [11:34]

• Most building regulation is local. Cities like D.C., New York, and San Francisco now require “bird-friendly” glass on new construction—especially up to 100 feet above ground.

  • "D.C. is one of them. So it passed this law recently saying you have to have bird friendly construction for like the bottom hundred feet of buildings..." — Nell [12:51]

• Notable change is happening: After McCormick Place, similar policies and renovations are taking root elsewhere.

  • “It's highly improbable that architects...are not aware now that this is an issue.” — Tina Phillips (Cornell Lab of Ornithology, paraphrased by Nell) [13:41]

8. What Individuals Can Do

• Focus on problematic windows—any you've heard birds hit, or near bird feeders, fruit trees, or with large reflective surfaces.
  • “Any window where you've ever heard that thunk...that needs to get treated.” — Brian Lenz (American Bird Conservancy) [14:50]
• Range of solutions: from DIY window painting to commercial bird-safe film/products.
  • “If you take those windows and put a bird-friendly solution on the outside...you probably will never hear another collision at your house again.” — Brian [15:20]

9. A Note of Optimism

• Growing awareness, local action, and citizen science are making a measurable difference for migrating birds.
  • “The least we can do is to make their journey a little easier.” — Emily [16:06]

Notable Quotes & Memorable Moments

• On the Quiet Hazards Above Us:
  “Huge numbers of birds are flying overhead.” — Nell [01:47]
• On Glass as an Evolutionary Trap:
  “They can encounter something that they have not been prepared for by evolution, and that is glass.” — Nell [02:14]
• On Effective Solutions:
  “The only thing [hawk decals] do is keep the birds from hitting the hawk decal.” — Brian Lenz [09:21]
• On Making a Real Difference:
  “It reduced bird collisions there by 95%.” — Nell, about Chicago’s McCormick Place [10:56]
• On Spreading Change:
  “It's just a matter of, like, is there enough public pressure?” — Nell [14:02]
• Personal Call to Action:
  “If you take those windows and put a bird friendly solution on the outside...you probably will never hear another collision at your house again.” — Brian Lenz [15:20]

Timestamps for Key Segments

• Migration & Night Flights: 01:41–02:14
• Artificial Lights & Glass Hazard: 02:14–02:56
• Volunteer Rescue Stories: 03:14–04:09
• Scope of the Problem (Cities vs. Homes): 06:02–06:43
• Hazardous Architecture & Data Gathering: 07:00–08:53
• Effective Window Treatments: 09:05–10:56
• Chicago Mass Collision & 95% Reduction: 10:05–10:56
• Bird Collision Prevention Alliance: 11:13–12:46
• Local Laws/Policy Movements: 12:48–13:27
• Personal Action Items: 14:40–15:33

Conclusion

The episode makes it clear: window strikes are a widespread, human-created hazard for migrating birds—but also a solvable one. Small changes (at home), significant architectural adaptations (in cities), and cooperative science-based advocacy are already having a substantial positive impact. The show calls listeners to notice, care, and act, so the invisible journeys of birds become safer and more successful for millions.

For further information or to take action, check out resources from Lights Out DC, the American Bird Conservancy, and the Bird Collision Prevention Alliance.