Weekend Science Fun: Beavers

Beavers are amazing animal architects.

Have you seen a beaver dam? We 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 the four front chewing teeth were bright orange. The orange color comes from the iron that strengthens a beaver’s teeth.

Beavers build dams to create deeper pools of water — called the beaver ponds — within a shallow creek. The structure where the beaver lives is called the beaver lodge. We didn’t see anything that looked like a traditional beaver lodge near the dam we found, but a book we read suggested if the conditions are right, beavers may simply use holes in the stream bank for homes.

Activity 1. Find out more about beavers.

Have you ever seen a real beaver?

Beavers are large rodents. A big one can weigh up to 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. That’s pretty incredible!

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


  • Pencils and colored pencils
  • Twigs and small branches
  • Chenilles
  • Blue construction paper or plastic wrap to represent water
  • Glue
  • Modelling clay
  • Pebbles
  • Age-appropriate scissors
  • Cardboard for base/support

Research how a beaver lodge is made, and then draw or build a model. 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 the canals that beavers use to float the trees to the lodge or dam.

Check out videos online that show beavers at work for ideas. Here’s a short one from PBS:

The BBC has a longer video narrated by David Attenborough.

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.

Public domain image from Wikimedia.

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


  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

    The water is part of the Little Colorado, near Springerville. We were actually there with a butterfly group.

  4. 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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