Architects of Nature Series: The Busy Brilliance of Beavers

The Architects of Nature blog series is inspired by the outdoor exhibition Architecture at Home, located near the museum’s entrance on the Orchard Trail. This exhibition brings together a wide range of voices to explore how architecture can prompt questions about human-centered design, housing attainability, and environmentally friendly design. In this blog series, we ask ourselves: what can nature teach us about these themes? Here, we uncover the architectural prowess of the American beaver.

“Innovative builder,” “environmental activist,” “picky vegetarian,” and “ridiculously cute” are generally not terms used in one sentence to describe architects. But this architect, Castor candensis, or the American beaver, can wear these words proudly. Rivaling the best home builders in America, these 30-foot long, 45-pound rodents locally source their materials and build home systems (dams, lodges, and canals) that can withstand the strength of water and thwart the cleverest of predators.

In order to appreciate just how well-adapted to home building these creatures are, we need to understand a little more about their lifestyle. With teeth that are self-sharpening, a multifunctional tale, and large claws for the nimble handling of wood, these animals are perfectly suited to chopping, dragging, stacking, and plastering their homes together. They can stay underwater for up to 15 minutes and they enjoy delicious meals of tree roots, leaves, and twigs consisting of maple, poplar, willow, birch, and alder. They mate for life, and their homes offer shelter to multiple generations of pups.

So what exactly is their home? It typically consists of three components: a dam, a lodge, and canals. The purpose of the dam is to create bodies of water with sufficient depth to allow them underwater access to their lodges during freezing temperatures. It’s also a way for them to avoid predators while moving back and forth between work (tree removal) and home life. To build the dam, the beaver finds a narrow portion of a stream and embeds sticks in the bottom of the stream bed, spreading the branches and packing them with stones, leaves, and roots. It uses mud to fill the voids. Dams are inspected daily and are maintained throughout the year, although new material is added mostly during times of high water. Think of this as the site work needed in order to build their house.

The lodge is the actual structure where beavers live. Their “framing” consists of trees and branches that have been cut with their teeth. Those strong jaws can remove up to 216 trees per year and fell trees up to 15 feet in diameter. No power tools needed here! Beavers are the innovators of tiny houses, needing only a feeding den and resting den to meet their square footage needs. Like human homes, safe points of egress are a must, so two tunnels are included in every home package and a source of fresh air is always provided. When freezing weather begins to set in, beavers will insulate their lodge by packing mud around the outside of it. This is a useful upgrade to their dwelling, adding a layer of protection against predators like coyotes and great-horned owls.

In addition, you can sometimes see a series of channels near a lodge. These channels provide a safe way for beavers to move construction materials (tree branches and trunks) to their lodge. They can also help connect bodies of water if water levels are low where the beaver lives.

Beavers are considered a keystone species. This means that the environmental changes they create benefit other creatures. When beavers create a dam, this can cause a waterway to overflow its banks, creating a wetland situation if the land remains inundated with water. This generates a whole new habitat for everything from turtles and frogs, to otters and ducks, and a multitude of wetland plants. Additionally, the damming of water slows down its movement, allowing the wetland plants to trap sediment and pollutants.

For all their benefits, these critters can be a nuisance as well. Flooding caused by their damns can drown crops in agricultural fields and burrowing along slopes can cause instability and erosion. Their tree removal services, when not wanted, can also cause headaches. Here at Crystal Bridges, we had one beaver that felled 24 large American holly trees! Director of Trails and Grounds Clay Bakker tells a very animated story of the trouble caused by this beaver. For weeks, holly after holly disappeared from the banks of Town Branch Creek without a trace. After much frustration, it was finally discovered that this clever beaver managed to build a lodge in a three-foot-wide drainage pipe!

Beavers and communities can coexist, and a great example of this is at Osage Park right here in Bentonville. Years ago, a beaver moved into an existing pond and turned it into a beautiful wetland habitat. The clean water from this habitat eventually flows into the Illinois River. However, this habitat sits close to a road so it was important to manage the beaver and make sure it didn’t increase its wetland effect onto the road. To accomplish this, the park managers devised a system to keep the water level consistent thereby tricking the lodge dweller into a sense of complacency. It’s a win-win for everyone!

Written by Samantha Best, outdoor interpretation specialist, Crystal Bridges.

Check out the rest of the Architects of Nature series:

• Spiders Make Good Neighbors
• Avian Builders and the Complexities of Bird Nests
• Mind Your Beeswax