© 2023 by Senior Residence. Proudly created with Wix.com

  • w-googleplus
  • w-facebook
  • Twitter Clean

For the past several years, beaver(s) have taken up residency in Lake Oscaleta...there are conflicting views amongst residents about whether the beaver(s) should be trapped or allowed to remain. There is a group of volunteers from the Three Lakes Council who remove one of the beaver dams at the Oscaleta Road culvert on, what seems to be, a weekly basis. Here are facts taken from Washington Department of Fish and Wildlife for your educational benefit. You can also contact the Three Lakes Council (www.threelakescouncil.org) for additional views and/or information. It is important to note that, according to Jan Anderson of the Three Lakes Council, if you are a waterfront owner, you have the right to set a trap at your personal waterfront to eradicate the beaver. That means the Two Lake Club residents who are shareholders in the beachfront have a right to set a trap at the beachfront...however, if must be presented to the Two Lake community as an issue and voted on. For more information, contact the Three Lakes Council or Jan Anderson.

 

Beavers (Castor canadensis) are the largest living rodents in North America, with adults averaging 40 pounds in weight and measuring more than 3 feet in length, including the tail. These semi-aquatic mammals have webbed hind feet, large incisor teeth, and a broad, flat tail.

 

Once among the most widely distributed mammals in North America, beavers were eliminated from much of their range in the late 1800s because of unregulated trapping. With a decline in the demand for beaver pelts, and with proper management, they became reestablished in much of their former range and are now common in many areas.

 

Beavers are found where their preferred foods are in good supply—along rivers, and in small streams, lakes, marshes, and even roadside ditches containing adequate year-round water flow. In areas where deep, calm water is not available, beavers that have enough building material available will create ponds by building dams across creeks or other watercourses and impounding water.

 

The beaver’s incisors (front teeth) are harder on the front surface than on the back, and so the back wears faster. This creates a sharp edge that enables a beaver to easily cut through wood.

 

Like many rodents, beavers construct nesting dens for shelter and for protection against predators. These may be burrows in a riverbank or the more familiar lodges built in the water or on the shore (shown here). However, the basic interior design varies little and consists of one or more underwater entrances, a feeding area, a dry nest den, and a source of fresh air.

 

Food and Feeding Habitats

  • Beavers eat the leaves, inner bark, and twigs of aspen (a favorite food), alder, birch, cottonwood, willow, and other deciduous trees. Beavers also eat shrubs, ferns, aquatic plants, grasses, and crops, including corn and beans.

  • Coniferous trees, such as fir and pine, are eaten occasionally; more often, beavers will girdle and kill these trees to encourage the growth of preferred food plants, or use them as dam building material.

  • Beavers have large, sharp, upper and lower incisors, which are used to cut trees and peel bark while eating. The incisors grow their entire lives, but are worn down by grinding them together, tree cutting, and feeding. (Fig.1)

  • Fermentation by special intestinal microorganisms allows beavers to digest 30 percent of the cellulose they ingest.

  • When the surface of the water is frozen, beavers eat bark and stems from a food “cache” (a safe storage place) they have anchored to the bottom of the waterway for winter use. They also swim out under the ice and retrieve the thick roots and stems of aquatic plants, such as pond lilies and cattails.

 

Like many rodents, beavers construct nesting dens for shelter and for protection against predators. These may be burrows in a riverbank or the more familiar lodges built in the water or on the shore (shown here). However, the basic interior design varies little and consists of one or more underwater entrances, a feeding area, a dry nest den, and a source of fresh air. 

 

Beaver Dams

  • Beavers flood areas for protection from predators, for access to their food supply, and to provide underwater entrances to their den. Flooded areas also wet the soil and promote the growth of favored foods (Fig. 3).

  • Beavers living on water bodies that maintain a constant level (e.g., lakes, large rivers) do not build dams.

  • Dams are constructed and maintained with whatever materials are available—wood, stones, mud, and plant parts. They vary in size from a small accumulation of woody material to structures 10 feet high and over 165 feet wide.

  • The feel and sound of flowing water stimulate beavers to build dams; however, they routinely let a leak in a dam flow freely, especially during times of high waters.

  • Beavers keep their dams in good repair and will constantly enlarge the dams as the water level increases in their pond. A family of beavers may build and maintain one or several dams in their territory.

  • In cold areas, dam maintenance is critical. Dams must be able to hold enough water so the pond won’t freeze to the bottom, which would eliminate access to the winter food supply.

 

Lodges and Bank Dens**(we have had bank dens built along the shore line near the BBQ grills...they are deep, be careful!)

 

  • Depending on the type of water body they occupy, beavers construct freestanding lodges or bank dens.

  • Lodges and bank dens are used for safety, and a place to rest, stay warm, give birth, and raise young.

  • Freestanding lodges are built in areas where the bank or water levels aren’t sufficient for a safe bank den.

  • Lodges consist of a mound of branches and logs, plastered with mud. One or more underwater openings lead to tunnels that meet at the center of the mound, where a single chamber is created.

  • Bank dens are dug into the banks of streams and large ponds, and beavers may or may not build a lodge over them  Bank dens may also be located under stumps, logs, or docks.

  • One family can have several lodges or bank dens, but will typically use only one den during winter.

 

Reproduction and Family Structure

  • A mated pair of beaver will live together for many years, sometimes for life.

  • Beavers breed between January and March, and litters of one to eight kits (average four) are produced between April and June. The number of kits is related to the amount of food available (more food, more kits), and the female’s age.

  • The female nurses the kits until they are weaned at 10 to 12 weeks of age.

  • Most kits remain with the adults until they are almost two years old. (Some leave at 11 months and a few females may stay until they are three years of age.) The kits then go off on their own in search of mates and suitable spots to begin colonies, which may be several miles away.

  • Beavers live in colonies that may contain 2 to 12 individuals. The colony is usually made up of the adult breeding pair, the kits of the year, and kits of the previous year or years.

  • Populations are limited by habitat availability, and the density will not exceed one colony per ½ mile under the best of conditions.

Mortality and Longevity

  • Because of their size, behavior, and habitat, beaver have few enemies.

  • When foraging on shore or migrating overland, beavers are killed by bears, coyotes, bobcats, cougars, and dogs.

  • Other identified causes of death are severe winter weather, winter starvation, disease, water fluctuations and floods, and falling trees.

  • Humans remain the major predator of beavers. Historically, beavers have been one of the most commonly trapped furbearers. In Washington, from 1991 to 2000, an annual average of 5,289 beavers were trapped. However, the average for the past three years has dropped to just over 1,000, due to RCW 77.15.194.

  • Beavers live 5 to 10 years in the wild.

 

Preventing Conflicts

Despite an appreciation for beavers and our best intentions to live with them, beavers can become a problem if their eating habits, and dam or den building activity, flood or damage property.

Before beginning any beaver control action, assess the beaver problem fairly and objectively. Are beaver really causing damage or creating hardship requiring control action? The very presence of beavers is often seen as a problem when, in fact, the beavers are causing no harm. You should also determine the type of damage or problem the animals are causing, and then match the most appropriate and cost-effective controls to the situation.

Once you have decided to control beaver damage, you have three control options: prevention, beaver translocation, or lethal control.

To prevent conflicts or remedy existing problems:

Choose and place plants carefully.
Plant areas with Sitka spruce, elderberry, cascara, osoberry (Indian plum), ninebark, and twinberry, because they are not the beavers’ preferred food plants. Densely plant aspen, cottonwood, willow, spirea (hardhack), and red-twig dogwood because, once their roots are well established the upper parts of the plants often resprout after being eaten. Planting preferred plants away from known beaver trails will limit losses.

Note: Beavers do use plants as construction materials that they might not eat.

Install barriers.
The trunks of individual large trees can be loosely wrapped with 3 foot high, galvanized welded wire fencing, hardware cloth, or multiple layers of chicken wire (Fig. 6). Barriers can be painted to make them less noticeable. Welded wire fencing coated with green vinyl that helps the fencing blend in is also available.

Lengths of corrugated plastic drainpipe can be attached around the trunks of narrow-diameter trees.

Note: Dark-colored pipe can burn trunks in full sun; wider diameter pipe or pipe with holes in it may prevent overheating problems.

Painting tree trunks with a sand and paint mix (2/3 cup masonry grade sand per quart of latex paint) has proven somewhat effective at protecting trees from beaver damage. The animals presumably don’t like the gritty texture.

Note: Preventing access to food sources may force beavers to eat other nearby plants, including roses and other ornamentals.

Figure 6. Various barriers can be used to protect plants from beaver damage. All plants should be protected to at least 3 feet above ground—or the snow line—and inspected regularly.
(Drawings by Jenifer Rees.)

Surround groups of trees and shrubs with 3-foot high barriers made of galvanized, welded wire fencing or other sturdy material (Fig. 7). (A beaver’s weight will pull down chicken wire and similar lightweight material.) Stake the barriers to prevent beavers from pushing them to the side or entering from underneath. An electric fence with two hot wires suspended 8 and 12 inches off the ground is also effective at protecting groups of plants.

Figure 7. Groups of plants can be protected from beaver damage by surrounding them with wire fencing.

Protect large areas that border beaver habitat by installing 4-foot high field fencing. Keep the bottom of the fence flush to the ground, or include an 18-inch wide skirt on the beaver side of the fence, to prevent beavers from entering underneath.

Groups of plants can be protected from beaver damage by surrounding them with wire fencing.

Apply repellents.
Commercial taste and odor repellents have provided mixed results, perhaps because they need to be reapplied often, particularly in moist weather. Taste and odor repellents are most effective when applied at the first sign of damage, when other food is available, and during the dry season. Two repellents that have had some success are Big Game Repellent® and Plant-skydd®. (See “Repellents” in Deer for additional information.)

Control the height of water behind a beaver dam to prevent flooding.
It may be possible to make a small change in the depth of a beaver pond by installing a flow device at the intended depth, extending upstream and downstream of the dam. This keeps the rise in the water level at a minimum by using one or more plastic pipes to continually drain the pond area (see “Flexible Leveler” below. Click to enlarge). For leveling systems to work properly, you will have to have at least 3 feet of water in the pond area for the beaver to stay.

 

Public Health Concerns

Beavers can be infected with the bacterial disease tularemia. Tularemia is fatal to animals and is transmitted to them by ticks, biting flies, and via contaminated water. Animals with this disease may be sluggish, unable to run when disturbed, or appear tame.

Tularemia may be transmitted to humans if they drink contaminated water, eat undercooked, infected meat, or allow an open cut to contact an infected animal. The most common source of tularemia for humans is to be cut or nicked by a knife when skinning or gutting an infected animal. Humans can also get this disease via a tick bite, a biting fly, ingestion of contaminated water, or by inhaling dust from soil contaminated with the bacteria.

A human who contracts tularemia commonly has a high temperature, headache, body ache, nausea, and sweats. A mild case may be confused with the flu and ignored. Humans can be easily treated with antibiotics.

Beavers are among the few animals that regularly defecate in water, and their droppings (like those of humans and other mammals) may cause a flu-like infection when contaminated water is ingested. The technical name for this illness is “giardiasis.” It is more commonly referred to as “giardia”—derived from giardia, the single-cell protozoan that causes the disease. Another popular term, “beaver fever,” may be a misnomer. It has never been demonstrated that the type of giardia beavers carry causes giardiasis in humans. Giardia has been found in many animal species, including pets, wildlife, and livestock.

 

Beaver Facts