Why Beavers Build Dams

Another guest post from our summer intern, Abbey White!

Beaver Dam at Lyman Woods

Beavers have a notorious reputation as “Nature’s Engineers” because they build their dams and lodges with remarkable speed and efficiency. In fact, they earned this title because no other animal (other than man) alters its environment to suit its own needs in such a way as to completely change the surrounding habitat. After all that time and energy spent building the dam, it is clear that these little workers are very pleased with the home they’ve created for themselves here at Lyman Woods. The craftsmanship and size of the dam is really a delight to see if you have the opportunity. Even though the beavers’ intent was purely self-serving when they began construction of the dam this spring, the result was much more complicated than that. They have created a mini-ecosystem that many other wildlife are now dependent upon to survive and reproduce. But before we get into the benefits of beaver activity on the environment, there is a more pressing question we must first answer: Why do beavers build dams in the first place?



Can you spot the beaver track?

Like all animals, beavers possess highly developed survival instincts, and these skills govern their behavior. Beavers are most threatened by wolves and coyotes, which are certainly much larger than our diligent little builders. Therefore, beavers live and die by an old adage: if you can’t beat them, outsmart them! Wolves and coyotes rule the terrestrial realm, whereas beavers have physiological traits, such as webbed feet, that favor an aquatic lifestyle. So rather than build a lodge on dry land where the risk of predation is high, why not create your own, personal water source? Beavers are very adept swimmers, so the newly concentrated water not only affords them safety from terrestrial predators, but also easy access to their lodge and the surrounding resources. The lodge, which is also made of broken branches and mud, has an underwater entrance that prevents virtually any animal (other than the occasional muskrat) from invading their privacy. Furthermore, the ability to swim up to the softwood trees, such as cottonwood and aspen, ensures that in the presence of a threat, the beavers can quickly retreat into the water.



The flooded boardwalk and south trail are a direct result of the beaver dam

Although oftentimes a nuisance to humans, these dams are actively maintained by beavers as an instinctual survival tactic. Thus, it was no surprise that when I notched a hole in the dam to drop the water level, the damage was immediately repaired with ten times the original amount of sticks and mud in that spot. The beavers are fast learners and adapt well to changes in their environment. Here at Lyman Woods we are excited to host a family of beavers that has built something so spectacular. This is nature at work and we hope you’ll take a look for yourself sometime soon! Don’t forget to bring your boots!