The Builders episode artwork

EPISODE · Apr 10, 2026 · 30 MIN

The Builders

from Radiolab · host WNYC Studios

In an episode first aired back in 2025 on our sister show, Terrestrials, we take you on a musical journey all about beavers. Few mammals have a bigger positive impact on the planet than the beaver. With its bright orange buck teeth, the creature is an expert engineer that brings life wherever it waddles and even fights fires. Our story begins in the Bronx river, once known as the  “open sewer” of New York City. After some humans decide to clean it up, we meet one of the river’s residents - José the beaver. We learn about the US government parachuting beavers out of planes into the mountains. And finally head to California where we discover how one beaver family saved acres of land from burning.  Special thanks to author Ben Goldfarb, Christian Murphy from the Bronx River Alliance and Dr. Emily Fairfax.  Terrestrials was created by Lulu Miller with WNYC Studios. This episode was produced by Ana González and sound-designed by Mira Burt-Wintonick. Our team includes Alan Goffinski, Joe Plourde and Tanya Chawla. Fact checking was by Diane Kelly.  Our advisors for this show were Ana Luz Porzecanski, Nicole Depalma, Liza Demby and Tovah Barocas. EPISODE CITATIONS: Books -  Eager: The Surprising, Secret Life of Beavers and Why They Matter (https://zpr.io/4QLuhrSMfurk), by Ben Goldfarb Beaverland: How One Weird Rodent Made America (https://zpr.io/3BbaViJK8Hk3), by Leila Philip’s Videos -  Watch the US government drop beavers out of planes (https://zpr.io/y2JJPwwyr3Bp).  Watch Leave It to Beavers (https://zpr.io/JVGZYmNCTy6h), a documentary about beavers restoring rivers and wetlands. Articles -  How reintroducing beavers can enhance ecological health (https://zpr.io/KNxz3MtKL9sV), by Madison Pobis, Stanford Report. Beaver Dams Help Wildfire-Ravaged Ecosystems Recover Long after Flames Subside (https://zpr.io/kAnjEUPvPUeJ), by Isobel Sandcomb, Scientific American  HEY GROWN-UPS! Love the show? Leave us a ⭐⭐⭐⭐⭐ rating and review on your podcast app—it helps curious listeners find us! We want to hear from you! Share your thoughts about Terrestrials with us.Subscribe to our weekly newsletter for bite-sized essays, activities, and ways to connect with the show.Follow us on YouTube, Instagram, and TikTok for behind-the-scenes extras and more.Listen to original music from Terrestrials on Spotify, Apple Music, or our music page. Got a badgering question for the team? Email us at [email protected] or submit a voice memo with your name, age, and your question using this form! Terrestrials is made possible in part by listeners like you. Support the show by joining Radiolab’s membership program, The Lab—and we’ll send you a special thank-you gift from our team!Leadership support for Radiolab’s science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

In an episode first aired back in 2025 on our sister show, Terrestrials, we take you on a musical journey all about beavers. Few mammals have a bigger positive impact on the planet than the beaver. With its bright orange buck teeth, the creature is an expert engineer that brings life wherever it waddles and even fights fires. Our story begins in the Bronx river, once known as the  “open sewer” of New York City. After some humans decide to clean it up, we meet one of the river’s residents - José the beaver. We learn about the US government parachuting beavers out of planes into the mountains. And finally head to California where we discover how one beaver family saved acres of land from burning.

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The Builders

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This episode is 30 minutes long.

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This episode was published on April 10, 2026.

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In an episode first aired back in 2025 on our sister show, Terrestrials, we take you on a musical journey all about beavers. Few mammals have a bigger positive impact on the planet than the beaver. With its bright orange buck teeth, the creature is...

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