Keep Me Wild: Beaver

North American Beaver (Castor Canadensis) is native to California and the largest living rodent species in North America, with adults averaging 40 pounds in weight and measuring more than 3 feet in length including the tail. Once among the most widely distributed mammals in North America, beavers were eliminated from much of their range by the late 1800s because of unregulated trapping and loss of suitable habitat. Beavers are a keystone species and ecosystem engineers, creating and maintaining much needed aquatic habitat that affects multiple species. Interest in link opens in new windowLiving with Beavers (PDF) in California is growing, as the benefits to fish and wildlife habitat, surface water storage and ground water recharge become more evident.

Because the activities of beavers can create conflict with agriculture, roads, infrastructure or human safety, CDFW does not issue permits for the relocation of beavers in California. Please consider living with beavers to help support California beaver populations and their benefits to terrestrial and aquatic habit.

Habitat Benefits

Beavers are well known for their construction efforts. They create dams and lodges for shelter and protection, largely with woody material. This woody material is either gathered from the ground locally or from small and medium-sized trees that the beavers fell with their specialized teeth. Beaver dams, canals and burrows create habitat for many other animals and plants of California. Deer and elk frequent beaver ponds to forage on shrubby plants that grow where beavers cut down trees. Weasels, raccoons, and herons hunt frogs and other prey along the marshy edges of beaver ponds. Sensitive species such as Red-legged, Yellow-legged and Cascade frogs, and Sage Grouse all benefit from habitat created by beaver wetlands. Western pond turtle and Willow Flycatcher also benefit from beaver ponds. In coastal rivers and streams, young Coho Salmon and steelhead rear in beaver ponds and bank burrows to find food and protection from high flows and predators while growing big enough to go out to sea. To learn more about beaver in California and the role they play in creating important aquatic habitat, go to link opens in new windowBeaver in California: Creating a Culture of Stewardship.

Tips for Preventing Conflicts

While the many environmental benefits of beaver to Public Trust resources in California are increasingly being recognized and valued, nonetheless at times beaver activities can cause problems. Therefore, before beginning a beaver control action, assess the problem and match the most appropriate and cost-effective controls to the situation. There are two basic control methods used in California: prevention and lethal control. It is almost impossible as well as cost prohibitive to exclude beavers from ponds, lakes, or impoundments.

Exclusion

Fencing off groups of trees or shrubs or garden plots with a low fence (3-feet-tall) will protect them. Since beavers generally do not like to stray far from water, fences may be effective even if they do not completely surround the area. The fence should be constructed of woven or welded wire and be well-anchored to the ground, so that beavers do not crush it, crawl under it, or walk over it. An electrified wire strung 4-6” above the ground may also be an effective beaver deterrent.

Protecting Trees and Plants

Valuable trees and other plants adjacent to waterways may be protected from beavers by encircling them with hardware cloth, welded wire mesh or sheet metal. Welded wire mesh of 2” x 4” is an optimal for effectiveness, durability, aesthetics and cost of construction.

Painting tree trunks with a sand and paint mixture may also prevent beaver gnawing and may be more aesthetically pleasing than metal barriers. The sand/paint ratio should be approximately 8 ounces (2/3 cup) of fine sand to one quart of exterior latex paint. A piece of bark can be taken to the paint store to match the color.

Preventing Flooding

Beavers need deep enough water to swim to their food sources while avoiding predators. This is why they build dams, dig canals and/or plug culverts to increase the depth and area of the inundation. Beavers are attracted to the sound of running water and will repair most dam breaches and plug most culverts and pipes that are installed in order to drain the ponds. A variety of devices and designs have been developed for controlling beaver impoundments and keeping blocked culverts open. The link opens in new windowFlexible Leveler and Beaver Deceiver are two examples.

Streambed Alterations

Modification of beaver dams, or any construction work within lakes or within the bed and bank of a stream, may require a Lake and Streambed Alteration Agreement from the California Department of Fish and Wildlife (CDFW). Contact your local CDFW office before attempting to install any beaver devices.

For questions and more information, contact your regional CDFW office.

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