Beavers and Wetlands: Nature’s Engineers

If you’ve been through a wetland or even been to Eagle Marsh lately and noticed a pile of sticks in the water, a lodge, or even a dam, you’ve more than likely found yourself some beaver evidence. As North America’s largest rodent, they do much more than chew on trees. Beavers are wetland engineers, create homes for wildlife, and their behavior and activities change throughout the seasons.

Beavers Through the Year

Spring

When the ice melts, the work begins. Starting in the spring, beavers repair any winter damage to their dams and lodges. They also start foraging and restocking their food supplies with fresh branches. This is also the time of year when beavers are having babies.

Summer

Summer is a time of growth and exploration. Beavers maintain dams and dig out channels, while young kits learn to swim and collect food. Around this time, the two-year-olds are encouraged to head out and start their colonies.

Fall

Ever heard of the phrase “busy beaver”? Well, you’ll find a lot of busy beavers this time of year. Beavers gather branches, especially willow, and store them under water to eat over the winter. They are also busy reinforcing their dams and lodges with mud, stones, grass, and other vegetation to fill gaps and seal any holes.

Winter

As we move into winter, you might be wondering… “Do beavers hibernate?” They remain active year-round but stay in their lodges during the coldest days and feed on the underwater food storage they created during the fall. Beavers will stick around as long as they have enough food. Also, during the winter between January and March, beavers mate, with babies being born in the spring.

Why Beavers Matter

According to the Beaver Institute, “A keystone species, the North American beaver, Castor candensis, is a vital ecosystem engineer. Their dams create wetlands that are among the most biologically productive ecosystems in the world, comparable to coral reefs and rainforests.” The creation of dams helps slow water, allowing water to filter into the ground, which can help raise the water table and recharge aquifers. These dams can also trap sediment and allow for better water quality downstream. By creating these dams, they also make large ponds that might be home to fish, amphibians, turtles, waterfowl, and more. If beavers ever move on from their lodges, either because the water is too low or for other reasons, other animals like muskrats or otters often utilize those homes.

At our preserves, you would more than likely encounter a dam along one of the flowing bodies of water, like the Graham McCullough ditch, but you would find a lodge, maybe near the former irrigation pond near the barn, where the water is not flowing.

Of course, sometimes their work can cause challenges, like flooding roads or clogging culverts. Our land manager, Don, keeps an eye on beaver activity, and we step in when needed—clearing debris, dams, unclogging culverts, or installing culvert screens—to keep both people and wildlife in balance.

The key is finding that balance. When water levels are stable and trees aren’t at risk, letting beavers do their thing is usually best. Their natural engineering helps keep wetlands strong, connected, and ready for the seasons ahead.

Join Us to Learn More

Want to learn more about beavers on our property? Join us for a Beaver Hike at Eagle Marsh on Tuesday, November 4, from 5:45 to 7:15 p.m. We’ll talk a little bit about beavers and explore how beavers shape wetlands, then hike out to look for signs of their activity on our preserve.

Come walk with us, ask questions, and experience the wetland world through the eyes of nature’s best engineers!