Beaver General Info

Beavers are America’s largest rodent and inhabit much of the United States. Many early European settlers made their living trapping these large rodents for their fur. Their fur was crafted into coats, hats, and other articles of clothing due to its warmth, softness, and water-resistant properties. 

Beavers have developed a reputation as woodland engineers because of their ability to construct dams using trees they collect from the woods. They also create canals and trails for easy access to food and building materials. Beavers also create lodges that are used as shelter from weather conditions and provide a safe place to rest, hidden from predators. They will feed on vegetation and woody material. Beavers may store food in a cache, especially during the winter months. Some wood is considered inedible to beavers, but they will still use these trees to build lodges and dams. Beavers do not always create structures; they only make structures when needed. They also readily create burrows in the side of a riverbank and may not create a dam if the water is deep enough. 

Beavers are social animals that will live with their children in small family groups. Generally, only the two adult beavers in a group will breed. The offspring eventually leave their parents to find a mate to establish a new dam-building family.

Beavers can be easily distinguished from other aquatic rodents, such as muskrats, due to their large size and flattened, broad tail. They will use their tail to smack the water's surface to warn other beavers of danger. Beavers also have large, orange incisors that they use to topple trees over by gnawing through the trunk. Since beavers spend much of their time in water, they have webbed feet that help them move quickly when they leave dry land. Beavers are uniquely suited to an aquatic lifestyle and can stay submerged for up to fifteen minutes. When on land, beavers are not very agile animals and are vulnerable to predators when they leave the water. 

Beaver dams are as well-known as the beavers themselves. Not many animals can create structures and maintain them in the same way beavers do. Some of the structures created by beavers are easily noticeable, although they will sometimes be challenging to find. To determine if a pile of sticks and mud in the water was put there by beavers, look for logs that have been gnawed on. Beavers chew on logs at the base in a pattern that makes the log come to a point. There will be incisor marks on the logs beavers have chewed, and the logs may resemble a pencil when they come to a point. 

Beaver dams are generally constructed from woody vegetation ranging from about ½ inch to nearly 2 inches in diameter. Beavers will build their dams in slow-moving streams whenever possible. They dam streams to raise the water levels to protect them from predators. Essentially, beavers build dams on streams to create a series of ponds. Beavers prefer areas where the creek bottom consists of silt and clay. Generally, beavers do not target areas with a rocky bottom. The dams are reinforced using mud and rocks. Beavers will improvise using other available materials without the “ideal” construction materials. Beavers start the dam construction at the sides of the body of water, then work towards the center of the stream. The middle section of the dam is the last to be constructed, since the middle of the stream is where the water flow is the most intense. If the stream has even flow, beavers build from one side to the other instead of doing both sides first.  Beavers will sometimes build multiple dams. The dams are maintained constantly to ensure they are still effective. Beavers will build a dam until the water levels reach a suitable depth. If water levels drop, beavers will add to their dam and patch any holes they can find. If the water is deep enough, beavers may not construct a dam. Dams are usually not built on large rivers, but ambitious beavers occasionally give it a shot. Beavers are meticulous when it comes to dam construction. Sticks for the dam are placed against the flow in streams with a lot of flow. Beavers will also take over abandoned dams in some cases. Most beavers build dams independently, but they have been observed helping one another when necessary.

Dams provide several services for beavers. Dams cause local flooding, which allows the beavers to traverse the landscape safely. During the winter months, the dams prevent water from freezing completely over. 

While many think beavers live inside their dams, they build other structures known as lodges where they take shelter. Lodges can take on a variety of shapes, sizes, and compositions. Lodges are not always easy to spot, and can sometimes be mistaken for floating debris in the water. Beavers will have “island” lodges, “bank” lodges, and “stick” lodges depending on the body of water they are in. Each of these lodges contains chambers for sleeping connected to the entrance through a series of tunnels. Beavers will construct additional lodges to create more space. Beavers will construct canals to allow them to travel from their lodge to other areas while remaining in the safety of the water. They will have smaller “day lodges” along canals that they can use to rest and hide from danger.

As with any animal, beavers will leave behind signs that can be interpreted to understand better how they use an area. Following the beaver breadcrumb trail can increase the effectiveness of management efforts or work to inform a landowner about what management efforts might be practical. Reading the signs animals leave behind is an entire discipline in itself. It takes practice and experience to interpret what the signs are saying. If some signs are unclear, confirm them with other evidence in the area.