7.9. SR 12-16-1996 - Laserfiche WebLink

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tions have been flooded by beaver dams (Figure 6). Road ditches, drain pipes and culverts have been stop- ped up so badly that they 'had to be dynamited out.and replaced, as well as bridges destroyed. The most unusual and difficultto explain was the beaver-cut tree by a highway bridge that, when felled, by the beaver, dropped across the hood of a family's automobile traveling down the highway. The damage caused by beavers is not also very frustrating to landowners and others. Identifying beaver damage general- ly is not difficult. Dams, dammed- up culverts, bridges, or drain pipes resulting in flooded lands, timber, roads, crops, and cut-down or gird- led trees and crops, or burrows in pond and reservoir levees or dams. Sometimes when drain pipes in a levee or reservoir are stopped up, it may be very difficult to get the sticks, logs, mud and debris re- moved so that the water will move out and beaver can be trapped. In large watersheds, it may be dif- ficult to locate bank dens. However, the limbs, cuttings and debris around such areas as well as dams along tributaries usually help pinpoint the area. Legal Status · The legal status of beavers varies from state to state. In some states the beaver is protected except dur- ing furbearer seasons; in others it is classified as a pest and may be taken ye ar-round when'~¢aus~ng~' damage. Because of its fur value, dam building, and resulting water conservation, it is generally not considered a pest until economic losses become extensive. However, fur prices for beaver in some states, particularly in southern states, make it hardly worth the skinning and stretching. In some northern states, trapping is pro- hibited near lodges or bank dens to protect and perpetuate beaver col- onies; however, fur prices for beaver pelts are substantially higher in these areas. Before attempting to trap or other- wise take beavers in any state, always check the existing regula- tions. Damage .Prevention and Control Methods Exclusion i3~avers carT' be: ex.~r~ded,~from· .... ponds, lakes or impoundments. However, if the primary reason for fencing is to exclude beaver, fenc- ing is not practical. Fencing of culverts, drain pipes or other struc- tures can sometimes prevent damage, but often results in a dam with the beavers using the fence as construction material. Metal bar- riers around valuable trees may prevent damage where feasible. Cultural Methods Because beavers usually alter or modify their aquatic habitat so ex- tensively over a period of time, most practices generally thought of as cultural have little impact on beavers. With the exception of the elimination of food sources and in cases where the aquatic habitat can be eliminated, most other cul- tural practices have no significant impact on beavers. Daily tearing out dams and removing dam con- struction materials will (depending on availability of construction ma- terials) sometimes cause a colony or individual beaver to move to another site. HOwever, theymigh~' ~ be even more troublesome at the new location. The use of a three-log drain or other type of structural device which prevents beavers from con- trolling the water level will occa- sionally cause movement to other habitat. However, once beavers have become commonly abundant in a watershed or in a large con- tiguous area, such as a stream system, swamp, or 'other wetlands area, periodic replacements or rein- vasions of suitable habitat can be expected to occur. Repellents There are no chemical repellents registered for beavers. Some research efforts in past years have tried to determine the effec- tiveness of potential repellent ~ materials, however, none were found which were effective, reg- . vironmentally safe, or practical. One study in Georgia using a deer repellent (Hicks 1978)indicated some potential benefit. Many mechanical devices have been tried in attempts to repel beavers. The only effective and en- vironmentally safe methods known do not in effect repel beavers, but do in some cases prevent damage. These would include fencing of structures in some areas, e.g., drain pipes or structures, fencing or Other barriers around valuable trees, shrubs, or other crops, and construction of concrete 0r other permanent materials in spillways or other drainage systems. As alluded to in an earlier section, in some drainage systems, total elimination of foods (aquatic vege- tation and trees adjacent to the drainage system) will, where feas- ible, usually prevent colonization. Continual destruction of dams, especially where construction materials are scarce, will some- times cause abandonment of the .~,~aL ar~:~owev, e~,person al observations have included dams constructed entirely of mud and crop materials, such as soybean plants, corn stalks, watermelon vines, cane, grasses, rice, wheat and others. The author has also . observed dams constructed of mud and other native plant materials, aside from trees, such as vines, water lilies, cattails, ragweed, pigweed, coffeebean, and others. Beavers are adaptable and will use whatever materials are available to construct dams -- fencing mater-