12/23/2022

How The Humble Beaver Shaped A Continent

12:24 minutes

a beaver peeking through tall grass in a marsh.
North American Beaver at Carburn Park in Calgary, Alberta. Credit: Chuck Szmurlo, Wikimedia Commons Attribution 2.5

The American beaver, Castor canadensis, nearly didn’t survive European colonialism in the United States. Prized for its dense, lustrous fur, and also sought after for the oil from its tail glands, the species was killed by the tens of thousands, year after year, until conservation efforts in the late 19th century turned the tide.

In her new book, Beaverland: How One Weird Rodent Made America, author Leila Philipp tells that tale—and the ecological cost of this near-extermination. But she also has good news: beavers, and their skillful engineering of waterways, have the potential to ease the fire, drought and floods of a changing climate. She talks to Ira about the powerful footprint of the humble beaver.

This book is the SciFri Book Club’s January 2023 pick. Find out more about our book club on this month’s main page.


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Segment Guests

Leila Philip

Leila Philip is the author of Beaverland: How One Weird Rodent Made America, and a professor of English at the College of the Holy Cross in Worcester, Massachusetts. 

Segment Transcript

IRA FLATOW: We’ve been talking about what happened when one town in New Hampshire lost its local beavers, but what happens when an entire continent loses the vast majority of this vital ecosystem engineer. That is, in fact, the story of North America after European colonization and the loss of beavers, and the effort to reintroduce them may shape what happens to our ecosystems, for better or for worse, under future climate change.

Leila Philip is here with me to tell that story. She’s the author of the new book Beaverland– How One Weird Rodent Made America. Leila, your book is really a “leave it to Beaver” story. Welcome to Science Friday.

LEILA PHILIP: Thank you so much. I’m so glad to be here with you.

IRA FLATOW: Nice to have you. I know you start this book with your own local story about your local beavers and how they turned a wetland into a pond. How dramatic was this change?

LEILA PHILIP: It happened so fast. So I walked past this swampy area with my dog probably every day and just didn’t really pay much attention to it, and then one day, we walked past. And it was just full of water. Beavers had cut down some trees and, in very short order, had swelled the water.

And what’s amazing about what beavers do is they’ll come to a creek– in this case, the little area near my pond was just a little trickling creek– and they swell it with a dam. And in this case they stayed in that area because it was a low area, and they didn’t need to move on. There was plenty of food.

After they cut down enough trees to build the pond, they then fed on the aquatic vegetation there. After the beavers made this pond, what was incredible was the biodiversity that followed. So many animals, just bobcats, and muskrat, and mink, and otters, it was just remarkable.

IRA FLATOW: And how much water do they store? After all, they are incredible engineers, as you say.

LEILA PHILIP: That was the other thing that was incredible, and I leaned into in writing this book because we know climate change is going to create far more devastating floods and fires, not to mention periods of extreme heat and drought. And beavers can help us deal with these problems because they bring water.

So to go to your question, they’ll go to a creek, and they’ll swell it out with water. And then they’ll move down further, and they’ll swell it out again. So what was once a single thread of water looks from above like a line of almost beads on a chain, and then the beavers will build canals into the woods on either side because they need them for transportation.

And so the water has a lot of interaction with the land. If you get a flood the water has a lot of places to go so that, instead of ripping through the stream system, the water has a chance to settle down. And this is why it may seem counterintuitive to people, but beavers actually help with flooding. And science has actually been supporting this with study after study in recent years.

And then around their ponds are these marshy areas that are wetlands. So a wetland, the water you can see is just the beginning because underneath imagine this giant sponge you can’t see. So every one of these beaver damming complexes is like a giant invisible sponge, storing water for times of drought. And we need that water, which is why beavers are so incredibly important to the health of the whole ecosystem.

IRA FLATOW: And you make that point in your book, that Indigenous peoples of North America knew what you’re telling me. They knew that beavers were crucial to the health of their ecosystems. They even forbade hunting of beavers, didn’t they?

LEILA PHILIP: They was one of the really interesting things that I learned when researching and writing this book. The Indigenous peoples that lived throughout North America understood the ecological value of the beavers. So the Algonquian peoples of the woodland areas of the Atlantic seaboard and up through the Great Lakes area had these wonderful stories of great beaver that are important teaching stories about beaver, and they had strict rules about how to hunt and harvest beavers.

And out in the arid northern plains, in places like Montana, the Blackfeet and other peoples out there actually had prohibitions against hunting the beaver because they understood the value of the beaver played in keeping water in the lands. So this knowledge base is something that, I think, it’s pretty interesting that our science now is almost catching up to. Geomorphologists, hydrologists, wildlife managers are all beginning to really understand and study the value of the beaver as what is called a keystone species.

IRA FLATOW: So you’re talking about how the country was filled with beaver, and then, in the book, it talks about how European settlers came in and totally disrupted the ecosystem.

LEILA PHILIP: Yeah, I think colonization was environmentally devastating on many respects, but the fur trade, which wiped out the beaver, geomorphologists now talk about that as the great drying because, basically, what happened was the river systems very quickly became degraded without beavers in them. So in what are called paleorivers, or rivers before colonization, you don’t have single channel rivers that we see today that run along one thread.

Instead, you would have multithreaded, braided creeks and streams that were messy and multithreaded and would overspill, contract, and then recede with the rhythm of the seasons. And so they were– imagine them as arteries or veins of water that were pulsing life into the land. That’s a river system that is working at peak hydraulic function. So when the beavers were taken out and no longer able to maintain the river system, you had really huge impact.

IRA FLATOW: At the height of the beaver trade, these animals were slaughtered by the tens of thousands every year. How did we get it together to protect beavers after this massive kill off? Did we realize their value?

LEILA PHILIP: Well, that’s what’s so kind of amazing and fantastic about this story is that, while we didn’t understand yet their value to us as environmental restoration partners, which we do understand now, but smart policies at the right time in the early 1900s brought beavers back. It’s part of this kind of counterintuitive North American wildlife program that we had, which was fantastically successful, and in a counterintuitive way, it was actually based on bringing wildlife back for hunting and trapping.

So at that time, the idea was to return wildlife as a hunting and trapping resource, but thank goodness, the beaver were returned. They rebounded. And now we understand that a live beaver is much more valuable than a pelt.

IRA FLATOW: This is Science Friday from WNYC Studios. But still, we just heard a story from New Hampshire where the public was pushing back against having a beaver pond because it got in the way of their snowmobiles and took their recreation away. So there is still– there is push and pull, is there not?

LEILA PHILIP: Yes, there’s always going to be human-wildlife conflict because we live where the wildlife have always been. But I have to say stories like that really give me pause because there are now very sophisticated methods for controlling beavers with nonlethal methods, and flow devices, and pond levelers. The places where I have seen those fail, often they have been jerry-rigged solutions that towns have done. The highway department has just put maybe some wire over the culvert.

And of course, beavers can just stick– stuff wire and block the culvert right back up. So I think it really behooves a town or a community to explore in a really full way nonlethal methods before they do things like start breaking the dam because breaking a dam is just often a very unproductive way of managing beavers. Either you drive the beavers away, and you have no more pond anymore, so you lose all that biodiversity and the beautiful pond, and the beavers go somewhere else to create a problem for someone else if habitat is limited, or the beavers may die because, if it’s November and they can’t have shelter in time, they’ll be– winter’s coming.

IRA FLATOW: This is such an interesting book. I learned so much from your book. For example, who knew that a million years ago beaver were as big as bears? Wow.

LEILA PHILIP: Yeah, yeah, isn’t that amazing? They’ve been on the continent for something like 37 million years, and I like to imagine beaverland. Imagine North America when there were 400 million beaver living on it and so much water pulsing through the land and the great boreal forests. No wonder there was a tremendous resource of wildlife that sprang up throughout the continent.

IRA FLATOW: Well, I want to ask you one last question about that, about 400 million beaver. You talk about that with climate change and the future challenges we’re going to face, how will beaver help us face those challenges?

LEILA PHILIP: It has been shown in study after study that beaver wetlands hold nine times more water than areas without beavers, so imagine if, in the coming times of drought, you have these big sponges of water in the land. That’s going to help everything.

Out West, there are now– the US Fish and Wildlife Service just funded a study looking not just can beavers help prevent wildfires but how many beavers where, so in other words, harnessing beaver wetlands to use as kind of speedboats for wildfires. And in flooding out in Milwaukee, there’s a study that was done in 2021– I write about this in the book– where they’re looking at the watershed of the Milwaukee river.

And they’ve estimated that if they put in literally 4,500 and I think it’s 63 beaver, they can create water storage for 1.7 trillion gallons of water. And that is water storage valued at $3.3 billion annually. And I think we should think about beavers like millions of highly trained engineers out there, ready to work for us for free, instead of instinctively thinking of them as nuisance pests. And I think if we can change that paradigm, we’ll be a lot better off.

IRA FLATOW: Unfortunately, Leila, we have run out of time. I want to thank you for taking time to be with us today.

LEILA PHILIP: Thank you so much for having me.

IRA FLATOW: Leila Philip, author of Beaverland– How One Weird Rodent Made America. And good news, bookworms, members of the SciFri book club will be reading Beaverland together, this January. You can find everything you need to get started, including upcoming events, a short excerpt to read, and a giveaway to win a free book. It’s all on our website sciencefriday.com/beaverland. That’s sciencefriday.com/beaverland.

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