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Why Do Beavers Build Dams?

Beavers are one of the largest rodents on earth. They have flat scaled tails, thick fur, strong teeth, and webbed feet. But they are most known for their dam-building skills. Did you ever wonder why they built these dams?

Beavers build dams by instinct. When they hear running water, they are compelled to do so to protect their homes from leaks. If you play the sound of flowing water on a speaker, a beaver will build a dam over it even if there is no water in sight.

Facts About the Beaver

Beavers are equipped with powerful jaws and strong teeth. Their upper incisors are from 20 to 25mm long. They continue to grow throughout their life. They use this to cut down small trees to build their homes and dams.

According to National Geographic, there are only two species of known to man. The American Beaver or Castor canadensis and the Eurasian Beaver or Castor fiber. The two species weigh about the same size and weigh about 60 to 70 pounds.

All beavers need water to survive; because of this, they choose to live around freshwater ponds, rivers, marshes, lakes, and swamps. These creatures have adapted to a semi-aquatic lifestyle with closeable nostrils, ears, and even transparent eye membranes. (Source: Live Science)

Where Do They Live?

A beaver lives in a home called a lodge. These lodges are dome-shaped and are often made out of sticks, grass, and moss. They are then sealed with mud to keep things in place. Some lodges can be as high as 3 feet and as wide as 8 feet.

Beavers are such amazing builders that they even have an underwater backdoor for easy access to swimming. (Source: Live Science)

How Do Beaver Dams Help?

Beavers play a huge role in our ecosystems. The dams they build change the flow of the river and prevent them from flooding low lands. These dams also prevent the soil from eroding. They also raise the water table, which allows sediments to settle and break down toxins. When sediments and debris build-up, the amount of nitrogen and carbon decreases. Because of this change in chemical composition, the type of species living in the body of water differs as well. This attracts new species of fish, amphibians, and birds. (Source: Live Science)

How Do Beavers Build Their Dams?

Back in the 60s, a Swedish biologist wanted to know if the dam-building behavior was innate or learned. So Lars Wilsson decided to experiment. He caught four adult beavers and raised them in different habitats.

Some were kept in an outdoor enclosure. At the same time, others were in a glass-walled terrarium. In the first phase of the experiment, he found out that the beavers acted upon instinct. By the second phase, he observed a set of beavers born in captivity and kept in isolation. He was able to see that they, too, started building dams that were close to perfect even on the first try.

At the end of the experiment, Wilsson found out that beavers are compelled to start building a damn with just the mere sound of running water. (Source: Mental Floss)

1 thought on “Why Do Beavers Build Dams?”

  1. Robert Peters

    How did this “instinct” knowledge of how to build a home (dam) EVOLVE over TIME?

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