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History |
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The beaver, Castor canadensis,
was an important part of the economy in North Carolina well into the 1800s.
Its valuable fur was the main item of trade in the colonies. As a result the
beaver was nearly trapped to extinction in many sections of the United States,
including North Carolina. The last report of native beaver taken in this state
was in 1897. In the 1930s and 40s several states began restocking programs.
In 1939, 29 beavers were obtained from Pennsylvania and released in North Carolina,
on what is now the Sandhills Game Land. By 1953, they had populated seven counties
and were estimated at nearly 1,000 animals.
Public demand for beaver stocking was high due to pelt values and aesthetic reasons. Because of this demand, the stocking program was continued between 1951 and 1956, and fifty-four beavers were trapped and released in nine counties including Cherokee, Henderson, Nash, Northampton, Person, Rockingham, Surry, Vance, and Wilkes. Currently, beavers occupy most of North Carolina's watershed systems.
Figure 1. Beaver populations are most abundant on Piedmont and coastal Plain streams.
The beaver is the largest North American rodent and its stocky, compact body is covered with rich brown fur. It has webbed hind feet and a broad and flattened scaly tail which is approximately 10 inches long and 6 inches wide. The average adult weighs 35 to 40 pounds and large beavers of 70 pounds have been reported. When they reach 2 1/2 years of age, they select mates for life. Breeding takes place during the months of December and January. After a gestation period of 3 to 4 months, the young kits are born from March to May. The litter size varies from one to eight kits with two to four being common. Only one litter is born per year. At about one month of age, the young beavers begin to follow their mothers to feeding areas. The young are driven out at about 2 years of age to start new colonies. A colony usually consists of five to seven beavers—two adults, two yearlings and two kits.
The most frequent misunderstanding about beavers is that many people think that beavers eat fish. Beavers are strict vegetarians adapted to a diet of the inner bark of woody plants and herbs. They eat a wide variety of trees and shrubs including sweetgum, poplar, willow, birch, boxelder, fir, pine, cedar, ironwood, privet and elderberry. Agricultural crops of corn and soybeans are also eaten and beavers may store cut sticks underwater for winter feeding. They show a particular preference for horticultural shrubs and tree farms, primarily due to the fertilizer applied to cultivated species.
The beaver is best known for its ability to construct a sturdy dam, creating a pond which floods vegetation and allows them to feed in an aquatic environment. If the food supply becomes depleted in or near a pond, beavers may relocate and build new ponds. These ponds may range in size from less than one acre to over 100 acres.
Beavers construct two types of houses or lodges apart from the dams. Pond lodges are constructed of sticks and mud and may reach 15-20 feet in diameter and 10 feet high. Bank dens are dug into exposed banks and are sometimes covered partially with sticks and mud. Dens and lodges usually have more than one underwater entrance to the dry protected nest site. The nest site inside the lodge is covered with wood shavings which are less susceptible to dampening than grass or leaf bedding.
Opinions vary widely on whether the beavers' activities are beneficial or detrimental, and depend on how the interpreter is affected by their activities.
Negative
Impacts
Generally, beavers' negative impacts affect man's land use
practices. Their ponds flood timber, agricultural crops, lawns, and roads. Their
dams obstruct bridges, culverts, and pond drains, causing erosion damage to
these structures. When feeding, beavers girdle and fell trees and shrubs, and
damage agricultural crops. Their bank dens and burrows often can weaken dams,
dikes, and road beds.
Positive
Impacts
The positive impacts of beaver presence generally
affect man's environment. Often beaver ponds are situated in areas that do not
interfere directly with man's land use practices. In these cases, the positive
impacts of beaver ponds far outweigh
the negative impacts by slowing run-off from drainage areas and retarding erosion.
They also filter silt, agricultural chemicals and pollutants from streams, and
generally improve water quality for fish, wildlife, and man.
Beaver ponds provide quality
habitat for other furbearers, waterfowl, fish, nongame wildlife and endangered
species. During periods of drought they provide water for wildlife, livestock,
and irrigation. Beaver ponds often provide abundant recreational opportunities
to sportsmen for hunting, fishing, and trapping. In addition, trapping for beavers
and other furbearers and leasing beaver ponds for waterfowl hunting can provide
valuable supplemental income to landowners.
Beaver ponds provide ideal habitat for ducks. North Carolina's native wood duck
populations increased significantly following increases in beaver populations
and wood duck harvest has more than doubled since the beaver population increase.
Wood duck nest boxes, combined with natural tree cavities in beaver ponds, make
these areas ideal brood habitat for wood ducks. In some instances, landowners
have partially drained the ponds during the summer, and planted them in Japanese
millet to provide winter feed for waterfowl.
Water
Level Control
In most cases, water level control can provide the
best technique for beaver pond management in situations where the removal of
the beavers is not desired or practical. Several types of drains proven successful
in controlling water levels include aluminum, PVC, and wood and steel. All of
these drains have one thing in common, small drain holes, which the beavers
are usually unable to obstruct. The three-log drain (Figure 2), made
of wood and steel, is the most economical. It is constructed with three logs,
nails, short pieces of wood and two pieces of tin or scrap metal. The disadvantage
of the three-log drain is its weight,
which makes it difficult to handle. Due to this, you may want to use a 6 to
10 inch diameter aluminum irrigation pipe or PVC pipe with three rows of 3/4
inch diameter holes spaced six inches apart along the bottom of the pipe (Figure
3). In addition to being lightweight, these drains are easy to construct, install,
and remove, when the area is ready to be flooded again. High rainfall and high
stream flow may prevent drainage unless several drains are installed in a beaver
dam. After three-log drains or pipe drains are installed, they should be checked
at least monthly and maintained as required to insure proper operation.
1 ) Break the dam at the existing channel in the form of a narrow, deep "V" (Figure 2).
2 ) Wait for the waterflow through the dam to lessen before beginning installation.
3) Install the drain with the upstream end completely covered by water (the intake side), and at least one foot lower than the outlet end of the drain. The outlet end should be at the desired water level of the pond. At least 10 feet of pipe should extend into the pond. Anchor the pipe on the upstream side with two metal stakes.
4) Once the drain is installed, the beavers will repair the damage to the dam. The drain pipe, however, will maintain the desired water level.
Figure
2. Water levels in beaver ponds can be managed to cornplirnent land use
practices through installation of log drains. 
Figure 3. Aluminum and PVC pipe drains can be used to manage beaver pond water levels and are also lightweight and easy to install.
Although beaver ponds are
naturally beneficial waterfowl habitat, in some cases they may be improved by
management. New ponds with live trees may be converted into green-tree reservoirs
to attract ducks, with minimal loss to timber production. Acorns are a preferred
food of many ducks, and oak trees can be maintained by draining the beaver pond
during the growing season from March through September. Remove the drain during
the dormant season (October-February) allowing the beavers to repair the dam.
Then the resulting flooded area will provide resting and feeding areas for waterfowl.
Old beaver ponds with dead trees and plenty of sunlight reaching the water surface
can be developed into attractive waterfowl feeding areas by draining the pond
during the growing season. One method is to drain the pond and rely on natural
vegetation to grow and provide waterfowl food. Another method is to drain the
pond and plant Japanese millet. Whether relying on natural vegetation growth
or millet plantings to produce waterfowl food, the drain should be set to leave
water on 1/3 to 1/2 of the pond area. If the pond is completely drained, the
beavers may relocate.
1 ) Broadcast Japanese millet seed on the soft mud at the rate of 25 pounds per acre. Millet should be planted by July 15 in the mountains to as late as August 14, on the coast. Additional land preparation is not needed, and fertilizer should not be necessary for the first two years.
2) Drains should be checked weekly to insure proper operation.
3) Remove the drains after the plants turn yellow and the seeds are mature. Seed maturity usually requires 45 to 50 days. Once the drains are removed, beavers will repair the dam and the millet will be flooded for waterfowl.
4) Drain the pond each summer to allow the millet seed to germinate and grow. In many ponds the original seeding of millet will provide enough hard seed for two to three vears before re-seedine becomes necessary.
In addition to providing attractive waterfowl feeding areas, beaver ponds provide excellent nesting and brood rearing areas for wood ducks. Initially, the use of wood duck nesting boxes will increase the number of wood ducks reared in beaver ponds. Yearly maintenance of wood duck nest boxes is essential to insure maximum use. For this reason, do not erect more nest boxes than you will be able to maintain annually. As the breeding wood duck population increases additional boxes may be erected up to a maximum of 7 boxes per acre.
Plans for an artificial wood duck house are shown in detail in Figure 4. Pay special attention to the entrance hole measurements, which are designed to keep out larger predators such as raccoons. For best results, use rough cypress lumber to build the box. However, you can use one-half inch exterior or marine plywood, or any other suitable lumber treated with a preservative such as copper napthanate or pentachlorophenol. If materials with a smooth inner surface are used, a four inch wide strip of 1/4 inch hardware cloth must be attached to the inside front wall from the floor to the exit hole, to enable the ducklings to climb out of the box. Boxes should be erected in early winter to insure maximum use, because wood ducks start selecting nest sites as early as January.
Figure 4. Erection of wood duck nest boxes will increase the attractiveness of beaver ponds to this native waterfowl species..
All houses should be securely fastened to some stable structure such as a post or tree in or near the water. They may be erected with no tilt or a slight forward tilt. Never tilt a box backward, since this prevents the ducklings from being able to climb the wall and leave the nest. All cracks or holes, except the exit hole and several drainage holes in the bottom, should be sealed or covered. Place boxes in relatively open areas with the entrance holes pointing either upstream or downstream so that that they may be readily found by the ducks. Do not shield the entrance with branches since wood ducks fly directly into the box and do not need to perch before entering.
Many wood duck boxes have become "death traps" because they were poorly constructed or not made predator-proof. Be careful to select locations that do not offer overhanging branches or other pathways for depredating raccoons, snakes, or other hungry animals. Always use the predator shield explained in Figure 4, or install the boxes on a smooth pipe. Boxes should be placed a minimum of three feet above the water or, when placed over land, at least ten feet above the ground.
Yearly maintenance will be needed prior to each nesting season. At this time be sure to remove all useless debris, replace or add wood shavings, check the box stability, and replace all broken hardware or rotten boards.
Prevention And Control Of Beaver Damage
Flooding caused by beaver dams on streams causes the greatest damage by killing trees where root systems are under water during late spring and summer. The three-log drain and pipe drains can be used to drain water and prevent drowning of trees in some cases. Occasionally, beavers can be discouraged from using an area after repeated complete drawdowns. In such cases, beaver usually move downstream and construct new dams. The site selected for the new dam and pond may cause more severe flooding for the landowner or adjacent neighbors.
Flooding due to beaver dams obstructing bridges, culverts, or pond overflow pipes may be eliminated by fencing the culvert or pipe opening. The best method is to build a horseshoe shaped fence (Figure 5 ) a few yards upstream from the bridge, culvert or pipe opening. The fence must be in close contact with the bottom. It is best to use metal posts to anchor the fence. The beavers will rebuild the dam using the fence as support and leave the culvert operational. If flooding is still a problem, pipe drains can be placed through the fence to maintain the desired water level
Figure 5. Horseshoe-shaped fences installed in the beaver pond upstream from culverts or bridges may be used to prevent the damming of these structures.
Beavers and muskrats frequently cut ornamentals and fruit trees near water. Trees can be protected from cutting or girdling by fencing the tree with hardware cloth or similar wire mesh extending 2-3 feet above the ground or high water level. Black or aluminum roof coating painted on tree trunks may reduce gnawing damage by beavers.
Beavers can be discouraged from using small farm ponds by eliminating trees near the bank or on the dam. This technique is effective only if the pond is separated from wooded areas by at least 100 yards of pasture or similar grassy cover. When beavers inhabit small ponds they frequently burrow into the bank to make dens. When these burrows occur in the dam, the entire dam may be washed out. When constructing pond dams in areas inhabited by beavers or repairing a dam damaged by beavers, they can be discouraged from burrowing into the dam if it is constructed with more gently sloping banks (at most a 3: 1 slope). A steeper 2: 1 slope on pond banks would encourage burrowing activity on the bank, rather than into the dam.
Few of the methods mentioned above to control damage will be effective if the beaver population is not managed by annual trapping. Trapping is the most effective and practical method for beaver control and management. In many cases landowners need to do no more than contact a local trapper to trap beavers. Many trappers will be happy to trap beavers during the regular trapping season, especially if they receive permission to harvest other furbearers. Even without trapper assistance, landowners should be able to remove beavers from problem areas because they are relatively easy to trap and do not require a major investment in equipment or time.
Beavers can be trapped with the 330 conibear trap by inexperienced individuals. North Carolina law requires that this trap must be set only underwater. Inexperienced trappers should use care when handling or setting the 330 conibear trap, due to its size and strength. Capturing beavers in leghold traps requires a higher level of trapping experience and should not be attempted by inexperienced individuals without instruction by an experienced trapper. The key to trapping beaver with the 330 conibear is to set the trap in a natural channel or crossing so that the beaver will swim into the trap. Frequently used channels or crossings are easily recognized by the freshly disturbed or smooth appearance of mud or vegetation, where they enter or leave the water. Three basic sets will allow the novice trapper to effectively control beavers in problem areas.
1 ) Channel Set (Figure 6)
The most productive places to trap beavers with 330 conibear traps are in channels which they use to travel between the lodge and dam and to feeding areas. The most frequently used channels are recognized by the 1-2 foot wide ditch cleared by beavers during low water periods to provide easier access to feeding areas. Because beavers normally swim on the surface when traveling to and from feeding areas, 330 conibear traps should be set so the trap extends several inches above the waterline. Traps may also be placed on the bottom of the channel if a floating dive stick is placed above the trap to make the beaver dive into the trap. Always try to select a trapsite along a channel where the beavers are forced to swim between natural obstructions, such as stumps or downed trees. In many cases it is helpful during high water periods to lower the water level by breaking a hole in the dam. This not only forces beavers to use these channels but encourages increased activity to rebuild the dam.
Figure 6. Trap sets placed in channels used by beavers to travel between the lodge, dam, and feeding areas are the most productive places to trap.
2) Lodge or Den Set (Figure
7)
The lodge or den set is basically the same as the channel set except the 330
conibear trap is placed directly in the lodge or den entrance. The trap should
always be set directly on the bottom of the channel, since beavers typically
dive to the bottom when leaving the lodge or den.
Figure 7. The lodge or den set is placed directly in the entrance to the lodge or den.
3) Dam Set (Figure 8)
Beavers generally cross dams at specific locations that are recognized by a worn appearance usually at the point where water flows over the dam. If sufficient water is flowing through the dam crossing, a 330 conibear can be set on top of the dam where it blends into the dam's shaggy appearance. At dam crossings on older dams or where there is little or no water flowing over the dam, the trap should be set immediately below (downstream side) the dam. A dive stick or a fence of dead sticks can be used to guide the beaver into the trap. Dam sets using the 330 conibear trap are the least selective sets because otter and muskrat commonly utilize the same crossings when traveling to and from beaver ponds. In areas where otter are present, dam sets should only be used during the regular trapping season and in areas where otter may be legally taken to prevent unnecessary loss of this valuable furbearer.
Figure 8. Dam sets may be placed either above or below the dam.
Every effort should be made to trap beavers during the annual trapping season because this is the time of year they are most active and susceptible to trapping. A depredation permit, issued by the North Carolina Wildlife Resources Commission, is required before a landowner can trap beavers out of season. Depredation permits may be obtained from any wildlife enforcement officer or biologist after a field investigation of beaver damage. The permit will allow the landowner or his designated agent to trap beavers on the property for a specified period of time. The district biologist also maintains a list of trappers who have agreed to assist with beaver problems. A permit is also required before a beaver lodge can be destroyed. However, landowners can destroy dams or shoot beavers any time the animals are destroying property.
Skinning (Figure 9)
The feet and tail should be removed at the hairline with a small axe or by cutting with a knife to separate the tail vertebrae and leg bones. A cut is then made through the skin from the base of the tail up the belly to the center of the lower lip. Care must be taken to avoid cutting into the muscle tissue and opening up the body cavity. The outer two inches of the pelt are "clean skinned" by cutting away connective tissue and fat from the pelt. The rest of the belly skin is removed by cutting more quickly, leaving more muscle and fat on the pelt ("rough skinning").
With the feet removed, it is easier to skin around the stump ends by pushing them up with the last three fingers while rolling the skin held between the thumb and index finger downward. The beaver can now be rolled on its side and the pelt cut away to the center of the back from neck to tail. The skinned half of the pelt is laid back over the carcass and the beaver is turned around on the skinning table. The other half of the pelt is "rough skinned', in the same manner as the first half. The carcass is then laid on its belly and the pelt lifted and cut away from the base of the tail toward the head. Skinning the head requires several careful cuts around the eyes and ears. The pelt should be hung up and allowed to dry in a cool area. "Rough skinned" beaver pelts can be frozen and thawed out later to be fleshed and dried. The pelts should be folded over, fur side to fur side, and put into individual plastic bags.
The grayish castor glands located directly in front of the anus are used in the perfume and lure industry and are worth saving. They are easily removed by making one cut across the abdomen just above the glands. The glands can be peeled away from connective tissue keeping the connection between the two glands intact and hung over a wire to dry for about 10 days. They are sold by dried weight and can be sold along with the fur.
Figure 9. When skinning beaver properly, you must first remove the feet and tail at the hairline, and then make one cut through the skin from the base of the tail up the belly to the center of the rawer lip.
Fleshing (Figure10)
The next step in processing a beaver pelt is to remove all the fat, muscle and connective tissue left from the rough skinning process. The pelt can be fleshed over a rounded and pointed fleshing beam (Figure 10a). The fleshing beam is about 5 feet long and is anchored so it forms an angle of approximately 45 degrees between the floor and the chest of the individual doing the fleshing. Fleshing beams can be made quickly from butt end board slabs or 2 x 8 lumber. They can be made to taper gradually for use with a variety of furbearers or may be broader if used for beaver exclusively. Fleshing tools are available from trapper supply houses or a 10 to 12 inch carpenter's draw knife can be used (Figure 10b).
Place the center of the back of the beaver pelt on the point of the fleshing beam (Figure 10c). A towel or rag can be placed between the chest of the individual fleshing and the point of the beam to help hold the pelt in place. Starting from the tip of the beam, a swath of muscle and fat 1 to 3 inches wide should be cut from the center of the back down to the tail. The blade should be held at an angle so that the beveled surface is held almost parallel with the fleshing beam. Push the blade downwards and sideways to produce a slicing action. The pelt should be moved up frequently so all cutting is done near the pointed end of the fleshing beam. The pelt is then turned and a similar swath is removed from the center of the back to the nose and out to each side. Each quarter of the unfleshed pelt should then be fleshed clean. Care should be taken when fleshing the thin belly area and around the leg holes to avoid cutting the pelt. The fat tissue in these areas usually can be pushed away rather than cutting as is required for the back where thick fat and muscle tissue must be sliced away.
 Figure 10c. The beaver pelt is fleshed clean with downward slicing strokes of the fleshing tool starting from the denter of the pelt. |
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Stretching and Drying Pelts (Figure 11 )
Procedures used for stretching and drying beaver pelts vary with different trappers. The procedures described here have worked well in the past and require a minimum purchase of specialized equipment and materials.
After the pelt is fleshed and the fur has been allowed to dry, it is ready to be stretched. All that is needed is a 3 foot square sheet of 1/2 inch or thicker plywood, a ruler, nails and a hammer.
The pelt is hung up by the nose and measured from top to bottom. This distance plus half this distance plus 2 inches, totaled and divided by 2 should give you the diameter of the circle into which the pelt should stretch. An example is given below:
| Pelt length | = | 30 | inches | |
| + | 15 | inches | (1/2 pelt length) | |
| = | 45 | inches | ||
| + | 2 | inches | ||
| = | 47 | inches | ||
| ÷ | 2 | (divided by) | ||
| = | 23.5 | inches | ||
| (diameter of circle) |
A circle of this diameter can be drawn on the board and the 12, 3, 6 and 9 o'clock positions marked to provide a reference point for the first four nails. The pelt is then laid on the board fur side down and the nose and center of the tail nailed along the circle at the 12 and 6 o'clock positions. The sides are then nailed at the 3 and 9 o'clock positions. The skin should be pulled and nailed at points midway between these and other nails until nails are spaced at approximately one inch intervals completely around the pelt. Any fat left around the leg holes should be removed and the leg holes closed up with 3 or 4 nails. The stretched pelt should be further scraped of any remaining fat with a curved knife blade or similar tool. Drying boards should be placed on end in a cool dry area at least 6 inches apart. Under favorable drying conditions, the skins should be dry enough to remove from the boards within 7 to 10 days. Drying time can be reduced to as little as 2 days if fans and artificial heat are used. Heaters should be used only to dry the air under humid conditions. Excessive heat and direct sunlight should be avoided to prevent pelt damage.
Figure 11. Beaver pelts should be switched into a circle when nailed to the drying hoard.
Acknowledgements
The following publications along with the authors' experience were used in the preparation of this pamphlet: