Why beavers build dams

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 

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