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Species: Beaver
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Identification |
American Beaver |
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| Legal In Virginia there are many laws that pertain to beaver. The Virginia
Department of Game and Inland Fisheries recognize that beavers
can have adverse effects to property, therefore they have added
additional legislation that allows for the taking of beaver out
of season despite its fur-bearer classification. In Virginia it is illegal to
In Virginia it is legal to
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Management
Options CONTROL TECHNIQUES: To reduce the potential for damage to personal property, precautions should be taken before a beaver develops an interest in your property. As with most wildlife damage problems, no single technique exists that will provide absolute protection from beaver depredations. However, certain measures that are initiated in a timely fashion, maintained properly, and applied with an understanding of the habits or behaviors of beavers can reduce the likelihood of significant damage. People residing within the beaver's range (primarily owners of shoreline property) should recognize that beavers are clever and persistent animals and they may be able to circumvent some of the control techniques mentioned below. Therefore, anyone affected by beavers must be willing to implement a comprehensive management strategy involving multiple techniques. TOLERANCE: Knowing that beavers fulfill an important role in creating wetlands and providing new habitat for a variety of wildlife, an easy approach to dealing with beavers is simply to learn to live with them. Beavers are intriguing animals and being able to see how a beaver lives and to observe the engineering skills at work can be fun and educational. If a beaver has moved onto your property and is in a location that will not cause damage to driveways, septic systems, or landscaping, you may choose to leave the beaver alone. On small ponds and streams, a colony of beavers usually will leave the area after 4 to 7 years, or once the food supply they are dependent upon has been depleted. However, other wildlife species attracted to the pond the beavers abandoned will remain long after the beavers have left. PREVENTIVE MEASURES: Realistically, it is difficult to keep beavers away from your property once they take an interest in it. Techniques such as cutting down scrubby trees and other vegetation along the water's edge and into the adjoining upland have been suggested as means to eliminate potential food sources and construction materials that beaver would use. Theoretically, this should cause them to overlook your property for other areas with more suitable resources. However, this has not been shown to be a feasible method of keeping beavers off your land and likely would have only a minimal impact on beaver. REPELLENTS: There is only one product registered by the US Environmental Protection Agency for use as a repellent on beavers. The active ingredient in this repellent is denatonium saccharide, and the formulation is marketed under the trade name Ro-pel®. Ro-pel® is a bitter-tasting liquid that can be painted or sprayed on trees, shrubs, and ornamental landscaping to deter chewing. Ro-pel® would be most effective when used at the first indication of beaver presence or in areas where beavers are most actively feeding. However, as is true with many other repellents, frequent reapplication may be required to maintain best results. NON-LETHAL CONTROLS: Non-lethal controls used to deter beavers can be expensive and require substantial investment of time by a landowner to put them into use. Examples include the use of fencing and water leveling devices. Fencing * Heavy gauge woven wire fence (2 inch x 2 inch mesh size) can
be wrapped around the base of a tree and connected to itself using
strong metal fasteners to create a tree guard that a beaver cannot
pull apart. Never attach a guard directly to a tree with nails
or staples. The tree guard should be wide enough to allow for
normal tree growth (leave 1-2 inches of space all the way around)
and at least 3 feet tall to prevent the beaver from reaching up
and gnawing on the tree above the fence. Each guard should be
staked securely to the ground to prevent the beaver from pushing
under or lifting it (remember: put your support stakes inside
the guard or the beaver will chew them off!). In areas where substantial
snow cover may accumulate, tree guards should be taller to prevent
beavers from standing on packed snow and reaching over the top
of the guard. Water Leveling Devices Water leveling devices are used to manipulate the level of water behind a beaver dam or plugged road culvert without a need to remove the dam or destroy the beavers. These devices disperse the flow of water in a way that beavers do not detect a leak nor are they alerted to the strong sound of running water, which would trigger them to find and plug a suspected breach in the dam. Water leveling devices can be made from a variety of materials, including wood, logs, plastic and metal pipes, and mesh covered boxes or troughs. Some of these devices can be a bit complicated to build and most will require the services of a hydraulic engineer to properly assess or gauge the volume of flow in the water source and to determine how many leveling units would be needed to adequately handle that volume. Also, because alteration of a beaver dam may affect the integrity of the wetland system upstream from it, an alteration permit may be required under local, state, and/or federal wetland regulations; landowners must check with permitting authorities before any alteration work begins and construction of such devices is contemplated. Some examples of water-leveling devices include the following: * The Clemson Beaver Pond Leveler-this device consists of a
variable length, solid, 8-inch diameter, polyvinylchloride (PVC)
culvert pipe and elbow riser as a discharge unit coupled to an
intake device made from a 10-foot section of 8-inch diameter,
perforated PVC pipe surrounded by a cylinder of galvanized welded
wire (Figure
1). The height of the elbow riser will determine the elevation
of the water behind the dam. All of these devices are designed to be incorporated into the dam structure. Pipes should extend a considerable distance back into the pond and away from the dam (a minimum of 20 feet) to reduce the likelihood of detection by beavers and thus prevent them from plugging up the intake pipe. A key factor in assuring success with a water leveling device is to not drop the elevation of the water in the impoundment below a level that will expose the opening to the den or lodge. If that happens, beavers often will move either upstream or downstream from the existing dam and construct another structure that will reestablish water cover over the lodge opening. Therefore, correct installation of these devices requires time and some engineering knowledge. Water leveling devices often can be expensive; costs range from a few hundred to several thousand dollars, depending on the price of the construction materials and the number of devices needed to properly handle the volume of flow. However, when properly sized and placed, water control devices provide an opportunity for beaver and landowners to coexist without the serious threat of flooding. LETHAL CONTROLS: If all attempts to deter beaver from your land have failed, then removal of the problem animals may be necessary. Where damage to timber, crops, ornamental or landscape plants, septic systems, or roads has occurred, the owner or lessee of the property may receive authorization to remove a colony of beavers, but only after the damage has been reported to and verified by the local game warden (þ29.1-518 of the Code of Virginia, Wildlife and Fish Laws). The warden will issue a permit that clearly states any limitations on the taking of beaver (e.g., length of time permit is valid, authorized methods of kill, disposition of any carcasses) and requires that a report is sent to VDGIF that summarizes the outcome of beaver removal efforts. Two methods commonly used to remove beaver are trapping and shooting the problem animals. Other lethal methods of take, such as the use of poisons, are not allowed in Virginia. There currently are no toxicant or fumigant products registered by the US Environmental Protection Agency for use on beavers. Trapping-Trapping can be an efficient and cost effective means to manage beaver populations within watersheds. Although trapping will not prevent beavers from recolonizing suitable habitat in the future, it does provide affected individuals and communities with a methodology to keep beaver numbers in balance with society's desires and tolerances. Even though landowners may be allowed to use traps to capture beaver, many individuals today are not familiar with the technology nor do they possess the equipment and field skills necessary to be successful. Thus, trapping may best be left to professionals. Your local warden may be able to recommend a licensed trapper who would be willing to help you. Alternatively, representatives from the Virginia Trappers Association (VTA) might be willing to assist landowners wanting to have beavers removed from a property (for those with internet access, here is the homepage for the VTA). Two basic types of traps are available for taking beaver: live traps and kill traps. Live traps are designed to capture the animal alive and allow the trapper some options in the disposition of the captured animal whereas kill traps, as the name implies, are designed to put the animal to death as humanely as possible. Bailey and Hancock "suitcase-type" traps (Figure 4) are examples of live traps suitable for capturing beaver. However, by state regulation, any beaver captured alive by a homeowner may not be removed from that property and transported and released elsewhere. This restriction is intended primarily to prevent the potential transfer of a beaver problem from one area to another. The Conibear®, a type of body-gripping trap (Figure 5), is an example of a commonly used and authorized kill trap for beaver. Steel leghold traps also may be used to capture beaver. Snares with an opening of less than 12 inches in diameter and set with the top of the loop not more than 12 inches above the ground may be used, but only on private lands and only with written permission of the landowner. In situations where body-gripping or leghold traps or snares are used, trappers must possess the required license or permit and all traps used must bear a metal tag that displays the trapper's name and address. Specific details on allowable trap sets and sizes, dates of trapping seasons, and allowable bag limits are available in a summary of hunting and trapping regulations published annually by the VDGIF. Similarly, your local game warden can provide answers to any questions you may have about state trapping regulations. For additional details on specific trap sets and designs, readers are encouraged to review Miller and Yarrow (1994), cited at the end of this publication. Shooting-Although allowed by state law, shooting raises a number of practical and safety concerns. Many cities and towns have local ordinances that prohibit the discharge of firearms within their municipal boundaries. Before considering shooting as an option, you must first determine whether a firearm can be used in your area. Where shooting is allowed, special care should be taken when firing at or near water bodies. Rifle shots aimed toward water are subject to ricochet and slugs glancing off water can travel substantial distances; thus, care must be taken prior to pulling the trigger to verify that a safety zone exists well beyond the target area. To reduce the potential for ricochet, consider using a shotgun with heavy waterfowl loads or buckshot instead of a rifle. Also, whenever possible, beavers should be shot while they are on land. It is advisable that advanced notification be given to your local warden and/or police department if you intend to implement a shooting effort outside the normal hunting season. By so doing, you will save them time and effort that might needlessly be wasted in investigating and responding to calls of firearms being discharged in your area. Virginia Sources Managing Wildlife Damage: Beavers, Virginia Cooperative Extension Other Sources Beaver Damage Prevention and Control Methods, University of Arkansas Beaver Management in North Carolina Controlling Beaver, University of Nebraska Controlling Beaver Damage, Texas Cooperative Extension Prevention and Control of Wildlife Damage-1994 Wildlife Damage Management: Beavers, North Carolina Cooperative Extension
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Life History The beaver is North America's largest rodent. Adult beavers normally weigh 40 to 50 pounds, but exceptionally large animals may weigh up to 80 pounds. They range in length from 35 to 50 inches, including the tail, which normally is about 10 inches long. Beavers have short legs, strong digging claws on the front feet, and large, powerful, webbed hind feet used for swimming. The broad, scaly, paddle-like tail is used as a rudder when the beaver swims, and also helps steady the beaver when it stands on its hind feet. Although beavers communicate principally by using whines, grunts, hisses, and a variety of nasal sounds, they will slap the surface of the water with the tail as a warning to alert other beavers of potential danger. The tail also acts as a storage organ for accumulated fat to be used as a reserve energy source during the wintertime. Beavers groom and clean their dark brown fur daily using a modified (i.e., split) second toenail on each hind foot. The fur then is coated with a material produced by an oil gland located beneath the tail. This coating makes the fur water repellent. Properly groomed fur also is capable of holding a thin layer of air next to the skin to help insulate the beaver from the effects of cold water. The short ears and nose each have unique muscles and valves that close to keep water from entering when the animal is submerged, and each eye has a transparent membrane that protects it when under water. These adaptations make the beaver well suited for life in the water. Beavers have a compact head with strong jaws and sharp chisel-like front teeth adapted for cutting trees and peeling bark. The two center top and bottom teeth (incisors) grow continuously throughout the life of the beaver. These teeth grow at an angle such that they actually are sharpened every time the beaver gnaws on trees. Beavers have lived as long as 20 years in captivity, but normally average no more than 5 to 8 years of age in the wild. Although they are viewed as being primarily nocturnal (i.e., active at night), individuals can be observed during daylight hours, especially when dispersing to new territory or when repairing damage to a dam or lodge. Beavers are monogamous animals, which means they pair with the same mate for life. Mating takes place during January and February, and kits (young beavers) are born in May or June. The typical litter has 3 or 4 kits, but may have more or less depending on environmental factors and the physical condition of the female. A colony of beavers usually consists of the adult pair, last year's offspring (often called yearlings), and the current crop of kits. Once the yearlings have reached 2 years of age, they leave or are forced out of the colony by the adults and start new colonies of their own in other locations.
More information can be found at the Virginia Fish and Wildlife Information Service Web page.
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Disease Although incidence is rare, beavers may pose a potential threat to humans from several diseases associated with them or the habitats that they have created. Giardia limbia, a pathogenic intestinal parasite, can be transmitted or deposited with the feces of beaver and other mammals (including otters, mink, and even infected humans) into water systems. Drinking water supplies (e.g., ponds, reservoirs) that have been contaminated with Giardia and lack chlorination or fine mesh filtration treatment facilities can lead to the spread of giardiasis, an intestinal ailment that can be debilitating to those infected with the parasite. Another health concern, though much less common, is Blastomycosis dermatitidis (or Gilchrist's Disease). Individuals who have had recent contact with old beaver lodges and dams may be exposed to blastomycosis, a pneumonia-like disease that arises from the inhalation of fungal spores into the lungs. The spore-producing fungi reside in soils, decaying foliage, and vegetation, but the spores they produce cannot become airborne unless the soil or decaying material has been disturbed. Because very specific temperature, nutrition, and humidity conditions are necessary for the growth and production of the infecting spores, the incidence of blastomycosis is quite low. In several of the few documented cases involving beaver (e.g., in Minnesota), individuals became exposed while trying to dismantle or remove an old beaver dam. In cases of suspected exposure, treatment is available for both giardiasis and blastomycosis at most medical facilities today. There are many diseases that wildlife species are capable of carrying and transferring to humans (zoonotic diseases). While all zoonotic diseases are a serious threat to humans this website will only address those that are a concern for Virginia residents. Giardiasis - Giardiasis is an intestinal diarrheal illness typically contracted by drinking untreated water. Tularemia - Tularemia
is a life-threatening bacterial disease that can be transmitted
by all known epidemiologic routes.
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All map images © Virginia Department of Game and Inland Fisheries, from their VAFWIS website.
All species images © USDA Forest Service or U.S. Fish and Wildlife Service unless otherwise noted.
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