Growing With Science Blog

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.

What about the structure where the beaver lives, called the beaver lodge? We didn’t see 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. Amazing!

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?

For more information, try:

My son found this in the soil.

A caterpillar that curls into a “C”-shape when disturbed is probably a “c”utworm. Cutworm larvae tend to overwinter in the soil as caterpillars (larvae).

Although it is not very pretty, you can see the suckers of the prolegs. Prolegs are the fleshy, leglike appendages found on the abdomen of caterpillars.

This caterpillar will come out of the soil to feed on new seedlings in the spring. Once it is full grown, it will pupate and then turn into a drab grayish-brown moth. You probably won’t see the moth because it flies at night.

Once it uncurls, the caterpillar gallops off to safety.

See you in the spring.

I thought these seed pods were pretty.

I’ll give you a big hint. They are from a desert tree. Do you know which one?

Edit:  The answer is now posted.