What Hoppers got dam right about beavers

Hoppers” Beaver Expert Shares Wacky Facts About These Dam Builders

By Brianne Kane edited by Andrea Thompson

Field researchers will put considerable effort into studying animals in the wild. In Hoppers (2026), scientists may have reached the pinnacle of how far they are willing to go in the name of science: they jump into the body of a robot beaver and join a colony of beavers.

But what do true beaver experts actually do to study these industrious creatures? To help separate fact from fiction, Scientific American spoke with Emily Fairfax, who studies ecohydrology at the University of Minnesota and has worked with the Hoppers team to ensure the depictions of the beaver were accurate. (Her university’s website boasts: “When Fairfax says she can talk about beavers all day, she’s not kidding.”)

[An edited transcript of the interview follows.]

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In hoppers, scientists observe from afar, disguise themselves as animals and even send robots. Is this really how we study beavers in the wild?

We study wild animals this way. If you’re rehabilitating a baby animal, you may want to dress up as an adult version so it doesn’t learn that humans are its parents. We use robots, although I don’t shape mine like beavers. I fly drones in the field quite often. We also use trail cameras, which are cameras that we can attach to trees and study beavers. I think it would be amazing if we could jump into the body of a real animal and go in and communicate with it, because you can only learn a lot from a 10,000 foot aerial view.

In the film, beavers are considered a keystone species. What does this mean? Are there animals that could replace the beaver in a humid environment?

A keystone species is an animal that, for whatever reason, many other animals and plants depend on. Often our keystone species are ecosystem engineers capable of transforming the physical earth and creating unique environmental conditions. In the case of the beaver, what they do is: they create wetlands, and there are no animals other than beavers and humans that can go out and create wetlands. Additionally, we quite often try to imitate beavers for restoration purposes; we do things called beaver dam analogs, which are fake beaver dams, to try to get some of the benefits of the beaver dam itself.

Do you think you could build a dam as good as the beavers?

No chance. Even having worked as an engineer myself, I’ve said many times that the first time I went to a beaver pond, I realized I couldn’t do that with the same materials. Then I realized I couldn’t make it either if you gave me a backhoe and even gave me the plan.

Are the beavers working together to build these wetlands, or is it just one beaver on a mission?

No, family units are very important to beavers. Disturbing a beaver family is actually one of the most damaging things you can do to beavers, because their environment is designed to keep every beaver busy.

One of my favorite jokes in the film involves beaver oils. At one point, someone says they smell like vanilla, and our king beaver keeps trying to share his oils, but the recipient isn’t particularly interested. How accurate was this depiction and why do they have these oils?

It was disturbingly precise. Beavers have oils that they excrete [their rear end] and will pick up these oils in their paws while they groom themselves. Castor oils are called castoreum and come from the castor bags found inside the castor. In the 1970s and 1980s, if you ate or drank something that had “natural vanilla flavor” or “natural raspberry flavor,” it was actually beaver castoreum. So you have, in essence, tasted beaver butt juice.

The movie also begins with a very funny depiction of a class pet, but do you think beavers would actually make a good class pet?

Beavers would be the worst pets! You came back from recess and all your desks were destroyed and pushed into a dam. They are so stubborn. They are also big. Adult beavers weigh between 40 and 110 pounds.

The film overall deals with climate change and humans affecting natural habitats. How are beavers affected by these changes in the real world?

Fortunately, beavers are one of the most resilient species to climate change. Whether they’re in a prairie, whether they’re in a forest, whether they’re in the mountains or deserts, it doesn’t matter: they can create good wetland habitat. What poses a challenge for humans and beavers is that as the Arctic melts, permafrost disappears. Beavers have been to the Arctic several times during their evolutionary history, but each time they went, the Arctic was a jungle. So when we see them moving north now, we’re very concerned that they’re going to create more wetlands, which could accelerate the thawing of the permafrost.

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