Why Do Beavers Build Dams?


| LAST UPDATE 01/10/2023

By Daria Appleby
Beaver Dam Benefits Explained
Allison Shelley via Getty Images

If you've ever wandered through the woods and spotted large stacks or barriers of branches, then you might have wondered how these were constructed. Well, the rodents that scurry through the leaves built them. Beavers are habitual to the forest and renowned for building dams, but what effect does this have?

According to the National Park Service, beavers use their strong front teeth to construct dams from trees and branches. When there's a freshly fallen from above, that's the key target for a solid dam. With the help of surrounding nature, such as grass, rocks, and mud, beavers will gather the resources to "reinforce these structures," says LiveScience. When the work in the day is done, and the beavers are satisfied with their dam, it comes down to the question of, what now? Well, while they don't necessarily live in them, they are built for a substantial purpose. These dams help the beavers stay safe. However, the challenge of building these dams arises from their awkward and varied bodily shape; hence, the variety of dams built.

Beaver Dam Benefits
Allison Shelley via Getty Images
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Chris Jordan, a biologist at the National Oceanic and Atmospheric Administration Northwest Fisheries Science Center in Newport, says they are "smelly bags of meat with really short legs." This makes them easy animals to prey on as they are easy to sniff out and cannot outrun their predators unless they are in water. Their small legs provide the power to swim extremely fast whilst holding their breath for up to 15 minutes. But, each to their own. Still, by building a dam, they are deep enough for the animals to hide from predators such as mountain lions, bears, wolves, and coyotes. The dams also help create floods, which only results in their benefit. Despite the element of survival, dams benefit their creators and other species by slowing down the water streams and maintaining a landscape. Emily Fairfax, an ecohydrologist at California State University, says, "This transforms simple streams into thriving wetland ecosystems. The amount of food and water available in their wetlands makes them ideal habitats for many different species. That's part of why beavers are what's known as a keystone species." So, when water slows down, it is also stored in the soil, offering enough oxygen for plants to grow despite a drought occurring.

So, while we can scurry through the woods trying to avoid the big animal-made wooden clusters, we actually have to thank the wild animals. Not only do dams positively impact wetlands, but the carbon dioxide produced from vegetation can reduce flood damage. Fairfax highlighted, "it was remarkable how well-suited beavers are to not only survive changing climates, but also accomplish some of the climate change adaptation work we as people have been trying to get done ourselves."

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