What Hoppers is right about beavers

Containers‘ Beaver expert shares the wild facts about these dam builders

By Brianne Kane edited by Andrea Thompson

Field researchers will go to great lengths to study animals in the wild. IN Containers (2026), researchers have reached perhaps the pinnacle of how far they are willing to go in the name of science: they jump into a robotic beaver body and join a beaver colony.

But what exactly do beaver experts 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 worked with Containers team to ensure the beaver depictions were correct. (Her university 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, dress up as animals and even send in robots. Is this really how we study beavers in the wild?

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

In the film, beavers are referred to as a keystone species – what does that mean? Are there animals that can replace the beaver in a wetland?

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. As for the beaver, what they do is: they make wetlands, and there are no animals other than beavers and humans that can go out and make wetlands. Also, we try to imitate beavers quite often for restoration; 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.

Think you can build a dam nearly as good as the beavers do?

Not a chance. Even after working as an engineer myself, I have said many times that the first time I went to a beaver pond, I realized that I could not make it with the same materials. Then I realized that I couldn’t make this either if you gave me a backhoe and you even gave me the blueprint for it.

Do beavers work together to build these wetlands, or is there just one beaver on a mission?

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

One of my favorite running jokes in the movie is about the 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 in them. How accurate was this depiction and why do they have these oils at all?

It was disturbingly accurate. Beavers have oils that they secrete from (their rear end) and will scoop these oils up into their paws while grooming themselves. Beaver oils are called castoreum, and they come from the castor sacs, which are inside the beaver. In the 1970s and 1980s, if you ate or drank anything that had “natural vanilla flavor” or “natural raspberry flavor,” it was actually beaver castoreum. So you’ve essentially tasted beaver swamp juice.

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

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

The film 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 resistant species to climate change. If they are in a prairie, if they are in a forest, if they are in the mountains or in the desert, it does not matter: they can create a good wetland habitat. Something that has been challenging for people and beavers is that when the Arctic thaws, the permafrost will no longer remain. Beavers have been to the Arctic many times in their evolutionary history, but every time they’ve been up there, the Arctic has been 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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