Beaver in a dam
Beavers are more than just adorable rodents with dexterous paws. Practically every important historical event before the Civil War had a beaver connection.

Book cover of Eager: The Surprising Secret Life of Beavers and Why They Matter

In Eager: The Surprising, Secret Life of Beavers and Why They Matter (Chelsea Green, 2018), Ben Goldfarb ’09 reveals that our modern idea of a healthy landscape is wrong, distorted by the fur trade that once trapped out millions of beavers from North America’s lakes and rivers. It also reveals how beavers can help us tackle problems from drought to biodiversity loss to pollution to climate change. In his words, “It’s an optimistic, hopeful book about the ways in which our gravest mistakes can be rectified.” In the words of a Boston Globe reviewer, “This book lodges itself among the ranks of the best sort of environmental journalism.” Here, Goldfarb answers questions from fellow science writer Geoffrey Giller ’10. At Amherst, each double majored in a science and a humanity— Goldfarb in environmental studies and English, Giller in biology and French—before heading to the Yale School of Forestry and Environmental Studies, where each received a master’s degree in 2013.


Ben Goldfarb
Ben Goldfarb '09. As Goldfarb traveled the country, "I went further and further down the beaver rabbit hole to the point where, now, I'm basically incapable of talking about anything else." Photo by Robbie McClaran.

When did you realize that beavers are more than just big rats with flat tails?

Well, they’re not not big rats with at tails. Some of my earliest beaver encounters were on the bike path behind Amherst, where there are beaver dams and ponds and wetlands galore. I remember walking back there with my parents, maybe it was sophomore year, and coming upon a beaver that had pulled itself out of the water and was sitting on the path, eating cambium, the inner bark of a branch, just like you’d eat corn on the cob.

My true passion for beavers emerged many years later, when I was living in Seattle and working for a magazine called High Country News, which covers environmental issues in the American West. I met a biologist, Kent Woodruff, who was then director of the Methow Beaver Project, which live-traps “nuisance” beavers—beavers that have been chewing down people’s trees or flooding their yards by building dams and ponds—and relocates them to public land, where beaver wetlands can create great wildlife habitat without damaging property.

Kent took me to some of these sites. When most of us picture a stream, we picture a clear rapid creek bubbling over rocks, something you could wade or jump across. The streams that Kent’s beavers had created, by contrast, were swampy and broad and full of silt and decaying vegetation. With his help, I came to realize that those kinds of streams are often more natural than the classic clear, clean, straight stream, and that beaver-trans- formed streams can really do some good for the landscape. It was that realization— that my conception of a natural ecosystem was inaccurate—that I first found so compelling.  

A beaver dam
"When beavers build dames," Goldfarb says, "they create ponds that, instead of letting water run off right away, gradually release flows throughout the summer and fall."

Pond near a beaver dam

Is that how you became a “Beaver Believer”? And what exactly does the term mean?

Beaver Believers are a growing coalition of people, from scientists to government land managers to farmers and ranchers, who are convinced that beavers are incredibly important for all kinds of environmental reasons, especially water storage. The Beaver Believer movement has the most adherents in the American West, where rainfall is scarce and keeping water on the landscape is crucial, and where any entity that’s capable of storing water is valuable.

Beavers, of course, do that better than anything. When beavers build dams, they create ponds that, instead of letting water run o right away, gradually release flows throughout the summer and fall. They’re keeping water in streams that might otherwise go dry. Meeting Kent began my conversion to the cult of Beaver Believer- hood, and as I traveled the country, interviewing more people, I went further and further down the beaver rabbit hole to the point where, now, I’m basically incapable of talking about anything else. I’m this obsessive acolyte who won’t shut up about these flat-tailed rodents.

Beavers are obviously important ecologically, but reading your book, I was most struck by their importance in shaping U.S. history—their impact in several wars and in exploration of the Western frontier.

Along with timber and cod, beaver furs were the most important natural resource in the early history of the United States. Here’s one example: When the first colonists showed up in Massachusetts, they owed lots of money to their creditors back in England. They repaid those debts by trading for pelts with the Native Americans and shipping those furs back across the Atlantic. So it was really beavers that made the Massachusetts Bay Colony possible. From there, beaver trappers and traders spread across the continent.

Practically every important historical event before the Civil War had a beaver connection. The Louisiana Purchase, for example, was motivated in large part by the desire to secure more beaver trap- ping grounds. The route that became the Oregon Trail was discovered by beaver trappers. Of course, tragedy came with the beaver trade as well. Many smallpox outbreaks that destroyed Native American populations were precipitated by white beaver trappers transmitting disease to Native tribes in the course of trading for pelts. The story of beavers is the story of early American history, in all of its grandeur and destructiveness.

Reading your book, I came to understand that the West used to be a swampier place, in large part because of beavers. Out West today, there are many Beaver Believers, but also a strong resistance from farmers and ranchers, and even from state and wildlife officials. Why is there an entrenched anti-beaver bias in places where it seems like reintroducing beavers could do the most good?

She started growling at me, which was a sound I’d never heard a beaver make before.

Even in the Northeast, there is beaver animosity. The Pioneer Valley, one of the more beaver-y corners of this country, has a strong beaver resistance, largely because beavers love to build dams in road culverts, which often end up raising the water high enough to flood the road. In some respects I think we resent beavers because they’re so much like us. Along with humans, beavers are among the only animals that modify their environment to maximize their own food and shelter. The problem from a human perspective is that the beaver’s vision of good habitat is very different from our own. We prize order: we like our streams straight, our crops planted in parallel rows. Beavers, on the other hand, love creating what looks to us like chaos, streams interrupted by ponds and marshes and swamps, with side channels branching o everywhere and jumbles of downed wood clogging flows.

The fact is, good beaver habitat tends to be good human habitat: We both love settling in river valleys and alongside low-gradient streams. When colonists first arrived in North America, the most fertile farmland was actually located on the footprints left behind by old beaver ponds, these at, treeless areas covered in rich layers of organic matter. In the 20th century, as beavers recovered from trapping and returned to those habitats, you suddenly had millions of humans and increasing populations of beavers living in close quarters. We and beavers share a habitat—and an impulse to meddle.

Close up of wood chewed on by a beaver
Ben Goldfarb '09 holds a log bearing the bitemarks of a busy beaver. Photo by Robbie McClaran.

Beaver dams can cause flooding, which can cause infrastructure problems, but as you explain in the book, if you trap a beaver and then remove or kill it, more beavers will come in. One solution is the use of “Beaver Deceivers.” Can you explain what those are, and also why they haven’t been more enthusiastically adopted?

A Beaver Deceiver is one type of flow device—a system of pipes and fences that regulates the height of a beaver pond. Let’s say you have a stream in your backyard, and one day a family of beavers shows up and builds a dam, and all of a sudden your yard is underwater. And you say, “I like watching these beavers work, and I appreciate the birds and amphibians that have come to colonize this great wetland habitat. But I don’t want my yard underwater; that part is not so much fun.” What you can do is install a flow device, using the pipe to effectively create a leak in the dam and the fences to stop the beavers from clogging up the pipe. The idea is that the beavers can stay put, because you’re not draining their pond entirely—you’re just draining it to a level that you can tolerate.

The agencies that manage beavers often have long-term contracts with trappers, and they’re generally more accustomed to simply killing the o ending beavers—a strategy that’s basically like putting up a “Vacancy” sign for the next beaver colony. One of the flow-device experts trying to change America’s approach to beaver conflicts is a guy named Mike Callahan, who’s based in Southampton, Mass., very close to Amherst. He’s spreading the gospel of coexistence. That same bike path that I referenced earlier, the one that runs behind Amherst—if you go out behind the College tennis courts, make a left onto the path and walk for 15 minutes, you’ll see one of the first flow devices ever installed in Massachusetts. It has been totally effective in preventing the path from flooding. Amherst is, in some ways, ground zero for the propagation of this cool technique.

A beaver in the water
"Good beaver habitat tends to be good human habitat," Goldfarb says. "We both love settling in river valleys and alongside low-gradient streams."

I’d like to talk about the time you were attacked by a beaver.

I’ve tried to block it out of my memory. It was less an attack and more a mild moment of aggression, totally justified on the beaver’s part. Last year I went to the United Kingdom to research part of this book. In the U.K., beavers were trapped out hundreds of years ago, completely eliminated. Here in the U.S., we always had a remnant population that was able to re-establish after the fur trade eased up, but in Britain, beavers were utterly wiped out. In the last several years, conservationists have begun to reintroduce beavers to England and Scotland. These are European beavers, a different species than those in North America, but indistinguishable to the layperson. The U.K. beavers are imported from Germany and Norway. Be- fore you can release these imports into the wild, they have to go through a quarantine period. Most beavers do the quarantine at one particular farm in southwestern England.

I visited that farm and got right in a beaver’s face to take her picture. She started growling at me, which was a sound I’d never heard a beaver make before. I very foolishly ignored that sound, and then the beaver lunged at me and gave me a little nip on the ankle. Beavers have incredibly powerful chewing muscles and chisel-like teeth. They can do quite a bit of damage if you’re not careful. Fortunately, I did not experience the full brunt of that British beaver’s incisors.

In the book, you mention the only known fatality from a beaver: some guy trying to take a picture with a beaver, and it severed his femoral artery.

Yeah, a fisherman in Belarus picked up a beaver, and it bit right through his thigh. That is case in point of why you should not go around manhandling beavers.

A beaver dam
When most of us picture a stream, we picture a clear rapid creek bubbling over rocks. Beaver streams, in contrast, are swampy and broad and full of decaying vegetation.

Another reporting anecdote that stood out to me was your visit to Half-Tail Dale. I believe you were invited to smell him.

That’s right. Half-Tail Dale was a beaver from central Washington, a captive of the Methow Beaver Project that I described earlier. One curious thing about beavers is that the males have no external genitalia. After all, if you’re an animal that spends his life swimming through underwater piles of sticks, you don’t want anything that can snag, which is why all of their reproductive anatomy is internal. This makes it impossible to visually tell a male beaver from a female beaver. The only way to differentiate the sexes is by smell. Beavers secrete a strong-smelling substance that they use to mark their territories. So, basically, you have to pin the beaver down, squeeze out a dollop of secretion from its scent gland and take a whiff. If the stuff smells like cheese, it’s a female, and if it smells like motor oil, it’s a male. At least that’s what I was told. When I actually smelled poor Half-Tail Dale, I just got a very powerful whiff of beaver.

What other reporting stories stand out most in your mind?

Lots of Beaver Believers work in conservation and care deeply about environmental issues. But one of the cool things about this movement is that many of its most enthusiastic members are ranchers in conservative places, like northern Nevada. A highlight for me was spending time with these cattlemen, who are not prototypical environmentalists but have nonetheless become wholehearted Beaver Believers, because they recognize how important these animals are for storing water, irrigating pastures and creating forage for cattle. During one prolonged drought in Nevada, for example, ranchers who had no beavers on their land had to remove their cattle from the range, whereas the guys who did have beavers were able to weather the drought much more successfully. These old-school stockmen in Nevada have become great stewards of their beaver populations, because they recognize the benefits so clearly.

You’ve written many magazine features, but this was your first book. How was the process different from writing for magazines?

One thing that’s always frustrated me about magazine writing is how much you have to leave out. You’re always writing for a word count, and inevitably so much interesting material ends up on the cutting room floor. In a book, you can follow your curiosity wherever it leads.

One example is that beavers, for a long time, were hunted in Europe for their castor sacs, a set of glands that produce some of their scent secretions. Castoreum, the substance produced by the castor sacs, was long prescribed as medicine for everything from constipation to epilepsy; more recently, food companies used it as a flavor additive to soft drinks and ice cream.

Centuries ago, there was this myth, actually perpetuated by Aesop, that if a beaver was being pursued by castor hunters, he would chew off his own testicles and then throw them back to the hunters as if to say, “Just take what you need and let me go in peace.”

This makes no sense. Beavers have no external testicles to chew off, and castoreum isn’t produced by the testicles anyway. Even so, it was a widely cited urban legend. If I stumbled upon that anecdote in the course of researching a magazine story, I’d probably have to stick it in the scrap heap and just mention it at a cocktail party. But in the book, that kind of weird detail can go right in.

Were there downsides to writing a book? I know you dealt with some anxiety, including after the book was written, when you were worried about how you’d described certain stream restoration techniques.

When you write a book, you’re trying to write a definitive document, and with that comes some pressure of representation. One of the hard things about being a writer is that you’re telling other people’s stories. I’m the conduit for people who have worked for decades on beaver issues, who know more about beavers than I ever will. I am the imperfect mouthpiece through which they speak to the world, and that can be intimidating, but it’s also what it means to be a writer or a journalist. I’ve tried to make peace with that.

It seems like beavers can be a significant solution to some of the water woes out West. Are you hoping that this book could affect water policy there?

My book’s primary audience is the layperson who wants to learn more about these amazing animals and how they’ve shaped our world and our history. But there’s also a secondary audience of experts: people who work in water management, wildlife biology or conservation and could potentially use Eager to inform their decisions. So, sure, I do think about the ways in which this book could guide policy. I just did a spot for a public radio station in Colorado about this libertarian gubernatorial candidate who basically has one plank in his platform, which is: “We need more beavers to store water in Colorado’s mountains.” Practically the entirety of his candidacy is built on beavers. Maybe that’s a sign that these strange niche rodents are entering the zeitgeist.


Geoffrey Giller ’10 has written for Discover, Scientific American and several other publications. His last piece for Amherst was the Fall 2017 feature on geologist Frederic Brewster Loomis, class of 1896, who unearthed the College’s mammoth skeleton.