You may think that only “humans” can build houses and develop the environment, but in fact, there are other creatures besides humans who can change the environment by their own power.
That’s what beavers are. An adorable beaver with a slightly goofy face and short limbs.
It is a popular character that is also the subject of anime movies, but the detailed ecology is not well known. Let’s take a closer look at how beavers live!



~ Basic information. ~

Mammalia-Rodentia-Castoridae-Beaver genus.


Tail length:21-50cm(Width about 15cm。)


There are only two types of beavers classified in the genus beaver.Eurasian beaver distributed in Germany, France, Norway, Russia, etc. And it is an American beaver distributed in Alaska, Canada and the United States.

Their ecology is similar and they inhabit freshwater areas such as rivers, lakes and ponds and their surroundings. Some areas have become extinct due to overhunting for high-quality fur, but now conservation activities are becoming more active and the number of individuals is increasing.

Next, let’s check the physical characteristics of beavers. Beavers have a high ability to “gnaw” and their teeth contain a lot of iron for that purpose, making them very hard. The hardness is such that even trees with a diameter of 10cm can be felled in a few minutes. In addition, as aquatic rodents, they are second in size only to capybaras.

The body color is brown, but there are individual differences and the color varies depending on the habitat. White hair that is excellent in water resistance grows inside the hair and is an important point that enables life in water.


The tail is flat and generates propulsion by moving up and down when swimming. Beavers are nocturnal and are rarely seen during the day.

They usually live with their family and form a community with their spouse and immature children. It can be said that they are very similar to humans. Beavers are very wary animals, so do not approach them carelessly. This is because it is not uncommon for them to be attacked.

Thinking “It’s okay to be attacked because it’s cute” is dangerous. Beavers have teeth that can chew down trees in a few minutes. It is also easy for them to injure humans, and there is a risk of life-threatening injury if an artery is damaged.




Beaver’s Q&A.

Where does Beaver get its name?

The origin of the name is believed to be the old English word “beofor”.

If we dig deeper, it comes from the Indo-European language (a hypothetical language constructed as a common ancestor of the Indo-European languages) “bhe-bhru-s”, which means “brown”. In other words, we can see that the name beaver comes from the color of its body.

By the way, the Japanese name is “umidanuki” but it is rarely used now. Beavers are not marine creatures, so they can be misleading.

※The sea is called the “umi ” in Japanese.


Why do beavers live there?

Beavers live in rivers and lakes in forests and mainly live in water. They need to protect themselves from natural enemies and rarely move on land. They may eat near the shore, but it can be said that it is rare to see them.


What do beavers eat?

Beavers are herbivores and eat up to 2kg of leaves, grass, and tree bark a day. They especially like leaves and often chew down trees themselves to eat them.


It’s a feat that they can do because of their strong teeth. Also, if the branch is less than 1m long, they can eat it all in just a few minutes. Although it looks cute when they hold food with both hands and eat it, I can’t help but be surprised by their method and amount of food!


Are there any creatures that look like beavers?

Animals that are often compared to beavers are capybaras and nutrias. In particular, the nutria, which belongs to the rodent family, is very similar to a beaver.

The body shape is almost the same, but it is slightly smaller than a beaver. Also, it is easy to tell them apart because of the big difference in their tails.

While a beaver’s tail is flat and wide, a nutria’s tail is thin like a mouse’s. There are also differences in their ecology.


Nutrias also inhabit lowland freshwater areas like beavers, but there are exceptions. They can be found at altitudes of around 1,000m in the Andes, and have also been spotted in brackish and seawater areas in Chile. By the way, nutrias are also found in Japan as an invasive species and can be seen in the Kinki and Chugoku regions.

What are the natural enemies of beavers?

Beavers’ natural enemies are medium-sized carnivores such as wolves, coyotes, weasels and martens.

However, many of these natural enemies are not good swimmers. Since beavers mainly live in water, they are considered to be in an environment where they can easily avoid attacks from their natural enemies.

Why do beavers build dams?

Many wild animals build nests by stacking or assembling materials such as branches and leaves. Beavers’ nest-building process is not much different, but they have an amazing ability to adjust water levels by building dams.

The act of building a dam is instinctive and can be done without being taught. Specifically, they gnaw down trees near the water’s edge and assemble them with mud and branches to cross the river.

In the center of the lake created by the dam, they build a nest like a private room by assembling wood. The nest is higher than the water surface and is shaped like a mountain, with two or more entrances leading into the water.

Although there are air holes, it can be said that it is safe to enter the nest because they are not accessible to predators. Dams are usually about 20-30m long, but a huge dam measuring 850m was discovered in Canada’s Wood Buffalo National Park.

In this way, beavers are said to be “the only animals other than humans that can reshape their surroundings so that they can live comfortably.”


Is it true that all beaver families get along well?

It’s true.

Beavers, like humans, form communities with couples and immature children. Children start swimming in about 10 days, but do not leave their parents immediately.

They finally begin to become independent when they are about 2 years old, around the time when younger brothers and sisters are born. Living together as a family for a long time is something that can be done precisely because they get along well.




Type of beaver.

  • American Beaver
  • Eurasian Beaver