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Weekend Science Fun: Beavers

Recently my family was reading a book about animal architects and we were astonished at beavers' construction abilities.

Everyone knows about the beaver dam. We actually saw one in northern Arizona last summer.

We figured out it was a beaver dam because we saw their webbed footprints in the mud, we saw where trees had been gnawed off, plus we found a skull. How did we know it was a beaver skull? We recognized it because a beaver's four front chewing teeth are bright orange.

Beavers build dams to create a deeper pool of water called the beaver pond. The structure where the beaver lives is called the beaver lodge. We didn't see anything that looked like a traditional beaver lodge here, but the book we read suggested beavers may simply use holes in the stream bank if the conditions are right.

Activity 1. Find out more about beavers.

Beaver are large rodents, a big one weighs one hundred pounds. They are brown and have a large flat tail. Their feet are webbed for swimming. They eat plants, especially bark and twigs from the trees that grow around their ponds.

Check these beaver facts.

Building Behaviors
A new dam is started by a young pair of beavers. Young beavers set out on their own at roughly two years old. Beavers mate for life, and the mother beaver has babies each year. The yearlings from the first year stay and help with the new babies. Once their mother has her second batch of young, however, it is time to leave.

Photo by Steve at Wikimedia

If you think about it, not only do these young beavers go on to build dams and lodges in a new place and under different conditions than their original home, but also their only previous experience has been to help their parents repair the structures that had been already in place before they were born. They have never built a dam before, yet they are able to do so.

Activity 2. Build a model of a lodge or dam, or even a complete diorama in a shoebox.

Watch these videos from the BBC, narrated by David Attenborough. Note:  There is a pop-up ad on each one.

1. In this video beavers are building their first dam from mud and sticks and then the channels that lead to their food (beavers build canals away from the main pond to serve as ways to move branches and food back to the lodge). There is a brief clip comparing beavers to human builders.

2. This video shows the beavers building their lodge.

3. This video shows beavers in winter. Beavers do not hibernate, but continue to eat food that they've stored underwater.

Beavers generally have at least two entrances to their lodges that are underwater. Under a pile of branches and stems, there is a space for them to eat and sleep. At the top is a chimney for air circulation.

Think about how a beaver lodge is made, and then draw or build a model yourself. You might want to try using real twigs and branches, or chenilles to make the structures. Use blue construction paper or plastic wrap to represent water. Draw some beavers in the pond, and add some trees for them to build with and eat. If you do an entire diorama, be sure to include the beaver dam. You might even want to add canals.

Have fun and let us know if you have any questions or comments.

Have you ever seen a real beaver?

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4 thoughts on “Weekend Science Fun: Beavers

  1. rebecca

    Where in AZ was that photo taken? It reminds me of Queen Creek, near Superior, but I'm sure a lot of desert creeks look similar!

    Once when I was in northern Wisconsin I was setting drift nets in a stream at night to sample night-swimming invertebrates, and kept being startled by the very loud SLAP! of a beaver slapping its tail against the surface of the water, irate that I was disturbing his habitat at such an hour.

  2. Mike B.

    While we do live in the Beaver State, and I've seen dams before, I'm yet to see an actual beaver in the wild. I know folks like to have the dams removed to prevent flooding, which I suppose doesn't bode well for the beavers.

  3. Roberta

    Yes, beaver dams are supposed to be good for the ecology of an area, but it doesn't seem like it when its your property going under water.

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