BEAVERS

Damage Prevention and Control Methods

Exclusions

• Fence small critical areas such as culverts, drains, or other structures.
• Install barriers around important trees in urban settings.

Cultural Methods and Habitat Modification

• Eliminate foods, trees, and woody vegetation where feasible.

Trappings

Identification

The beaver is the largest North American rodent. Most adults weigh from 35-50 pounds, with some occasionally reaching 70-85 pounds. Individuals have been known to reach over 100 pounds. The beaver is a stocky rodent adapted for aquatic environments. Many of the beaver's features enable it to remain submerged for long periods of time. It has a valvular nose and ears, and lips that close behind the four large incisor teeth. Each of the four feet have five digits, with the hind feet webbed between digits and a split second claw on each hind foot. The front feet are small in comparison to the hind feet. The underfur is dense and generally gray in color, whereas the guard hair is long, coarse and ranging in color from yellowish brown to black, with reddish brown the most common coloration. The prominent tail is flattened dorsoventrally, scaled, and almost hairless. It is used as a prop while the beaver is sitting upright and for a rudder when swimming. Beavers also use their tail to warn others of danger by abruptly slapping the surface of the water. The beaver's large front teeth, bright orange on the front, grow continuously throughout its life. These incisors are beveled so that they are continuously sharpened as the beaver gnaws and chews while feeding, girdling, and cutting trees.

Habitat

Beaver habitat is almost anywhere there is a year-round source of water, such as streams, lakes, farm ponds, swamps, wetland areas, roadside ditches, drainage ditches, canals, mine pits, oxbows, railroad rights-of-way, drains from sewage disposal ponds, and below natural springs or artesian wells. Beavers build dams to modify the environment more to their liking. Beavers are adaptable and will use whatever materials are available to construct dams - fencing materials, bridge planking, crossties, rocks, wire, and other metal, wood, and fiber materials. Therefore, about the only available aquatic habitat beavers avoid are those systems lacking acceptable foods, lodge, or denning sites, or a suitable dam site.

Habitat

Beaver habitat is almost anywhere there is a year-round source of water, such as streams, lakes, farm ponds, swamps, wetland areas, roadside ditches, drainage ditches, canals, mine pits, oxbows, railroad rights-of-way, drains from sewage disposal ponds, and below natural springs or artesian wells. Beavers build dams to modify the environment more to their liking. Beavers are adaptable and will use whatever materials are available to construct dams - fencing materials, bridge planking, crossties, rocks, wire, and other metal, wood, and fiber materials. Therefore, about the only available aquatic habitat beavers avoid are those systems lacking acceptable foods, lodge, or denning sites, or a suitable dam site.

Food Habits

Beavers prefer certain trees and woody species, such as aspen, cottonwood, willow, sweetgum, blackgum, black cherry, tulip poplar, and pine, depending on availability. However, they can and will eat the leaves, twigs, and bark of most species of woody plants that grow near water, as well as a wide variety of herbaceous and aquatic plants.

General Biology, Reproduction, and Behavior

Beavers are active for approximately 12 hours each night except on the coldest of winter nights, but can also be seen during daylight hours. Beavers are generally monogamous creatures, and will give birth to 3-4 babies (kittens) at once between March and June. The animals have a relatively long life span, with individuals known to have lives to 21 years. Most, however, do not live beyond 10 years.

Damage and Damage Identification

Most of the damage caused by beavers is a result of dam building, bank burrowing, tree cutting, or flooding. Identifying beaver damage generally is not difficult. Signs include dams found in culverts, bridges, or drain pipes, often resulting in flooding. Some bridges have been destroyed because of beaver dam-building activity. In addition beavers threaten human health by contaminating water supplies with Giardia.

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ACKNOWLEDGEMENTS

The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee). It is will great gratitude and appreciation that we are able to pass along this useful information.