From: Subject: FOR-50 MANAGING BEAVER PROBLEMS IN KENTUCKY Date: Thu, 3 Jun 2010 14:26:14 -0400 MIME-Version: 1.0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Location: http://www.ca.uky.edu/agc/pubs/for/for50/for50.htm X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5931 FOR-50 MANAGING BEAVER PROBLEMS IN KENTUCKY FOR-50 
MANAGING BEAVER PROBLEMS IN KENTUCKY =
ISSUED:=20 9-91
REVISED:
Thomas G. Barnes=20

Historically, the beaver = (Castor=20 canadensis) was North America's most important fur resource. During = the=20 1800s, the unrelenting pursuit and uncontrolled harvest of beavers for = their=20 pelts led to extermination throughout much of the animal's range. = However, in=20 the early 1900s the beaver received protection. Because of this = protection and=20 resulting restoration efforts, including transplanting beaver and = changing land=20 management practices, the beaver made a remarkable comeback. Beaver = numbers=20 today are at, or exceed, their population levels before the arrival of = white=20 settlers in North America.
Beavers=20 sometimes cause problems or become a nuisance when their feeding and=20 dam-building activities conflict with man. This publication provides = information=20 on the identification, biology and natural history of beavers and how = their=20 feeding and dam-building activities can be prevented or controlled.=20

Identification
The = beaver, fairly=20 common throughout Kentucky, is North America's and Kentucky's largest = rodent. It=20 belongs to the family Castoridae. Adult beavers weigh between 35 and 60 = pounds,=20 with some reaching weights of 70 to 80 pounds. Adult beavers range in = size from=20 25 to 31 inches from the tip of their nose to the base of their = paddle-shaped=20 tail. Beavers typically have large heads, indistinct necks, thick, stout = bodies=20 and small ears and eyes.
Perhaps their=20 most recognized feature is a large, flat, hairless tail shaped like a = paddle.=20 This six- to eight-inch wide and 10- to 12-inch long tail is used for = support=20 when the beaver is on land and as a steering, swimming and communication = device=20 when it is in the water.
Beavers are=20 uniquely adapted for life in the water. They have short, stout legs = specialized=20 for swimming and working. The large, fully webbed hind feet are adapted = for=20 swimming, whereas the small front feet are very dexterous, nimble and = not=20 webbed. Beavers use their front feet for digging as well as for holding = and=20 manipulating small twigs while they peel the bark off with their teeth.=20
Other adaptations for an = aquatic=20 lifestyle include ears and nostrils with valves that close when the = beaver is=20 submerged, eyes that are set high on the head to allow the beaver to see = above=20 water when swimming and lips located behind the front teeth that close = when a=20 beaver is submerged, allowing it to use its teeth under water. =
Like many other rodent species, beavers = have a pair=20 of continually growing, large, orange front teeth (incisors). The beaver = must=20 keep the incisors worn back by using them daily.
Beaver fur, which was highly sought after and is = somewhat in=20 demand today, is comprised of a gray, soft, dense undercoat protected by = long,=20 coarse reddish-brown guard hairs. Color can vary from blond to almost = pure=20 black. Beavers carefully groom and comb their fur with oil from various = glands,=20 using the second claw on each hind foot, which is split lengthwise. = Grooming=20 with oil helps keep the beaver from becoming wet at the skin's surface. = The=20 beaver also has a pair of scent glands called "castor sacs." These = glands=20 produce a substance called castoreum which is used as a chemical signal = to other=20 beavers. It is almost impossible to tell the difference between male and = female=20 beavers unless the female is lactating and has swollen mammary glands.=20

Beaver Facts and Biology
The beaver=20 is one of a few mammals, other than man, capable of modifying its = habitat to=20 suit its needs. When beavers move into an area, they quickly begin = building dams=20 to modify the habitat more to their liking. Once the dam has been built = from=20 surrounding timber, the subsequent flooding causes growing timber to = die, and=20 other aquatic vegetation begins growing. Often, the new plants growing = around=20 the edge of the pond (willows, sweetgum and blackgum) are preferred = beaver=20 foods. Thus, good beaver habitat can be almost anywhere there is a = year-round=20 source of water. Appropriate habitat can include streams, rivers, ponds, = lakes,=20 large reservoirs, swamps, wetlands and drainage ditches.
Beavers are incredible, highly skilled engineers. = They build=20 dams on fast- and slow-moving streams to create a pond with a stable = water=20 level. They show unusual skill in selecting dam locations. The dam is = usually=20 constructed of sticks, mud and stones and provides the water impoundment = for the=20 main lodge.
Home to a beaver = is its=20 lodge or bank den, depending on the situation. Lodges are dome-shaped = structures=20 built of sticks and mud with a large interior chamber above the water = line.=20 Lodges vary in size from 6 to 40 feet, depending on the number of = beavers in the=20 colony. Beavers sometimes dig burrows into the banks of ponds, rivers = and=20 drainage ditches instead of building a lodge. All lodge and bank den = entrances,=20 normally two or more, are located underwater.
Beavers live in family units called colonies, which = range in=20 size from two to eight beavers (the average colony size is five to six). = A=20 colony consists of the adult pair, the current year's offspring (kits), = the=20 previous year's offspring (yearlings) and occasionally a 21/2 year old=20 offspring. Beavers are highly territorial animals, and they actively = defend the=20 colony's territory against outsiders by using scent marking. When = beavers become=20 sexually mature around age two, they leave their home colony to form a = colony of=20 their own.
Beavers mate in = January or=20 February. Two to four one-pound kits (similar in appearance to the = parents) are=20 born in March or April. Kits grow rapidly, nursing for approximately 60 = days,=20 and by six months of age they weigh between eight and ten pounds. = Beavers have a=20 relatively long life span for a wild animal. Most beavers do not live = beyond ten=20 years of age, although some may live 20 years or more.
"Busy as a beaver" appropriately describes beaver = behavior.=20 Primarily a nocturnal animal, beavers are active for approximately 12 = hours each=20 night, feeding and working on the dam. It is not uncommon to see beavers = during=20 daylight hours, particularly in large reservoirs. Most daily movements = are=20 centered around the pond and lodge. Individual movements vary greatly.=20
The female parent in the = colony is=20 relatively sedentary, occupied with caring for young during the spring = and=20 summer. Two-year-old beavers may travel five to six miles in search of=20 appropriate habitat conditions necessary for establishing a new = territory. Other=20 travels by individual beavers include wanderings by yearlings and adults = who=20 have lost their mates.
Beavers feed on=20 the cambium layer (just under the bark) of woody plants and a variety of = aquatic=20 and upland vegetation. Preferred woody foods include willow, birch, = maple,=20 alder, cherry and poplar, although they can and will feed on the leaves, = twigs=20 and bark of most species of woody plants. During the summer beavers will = also=20 eat water lilies, pond weeds and cattails. Sometimes beavers will travel = substantial distances from the pond or stream to get to corn or soybean = fields,=20 where they cut the plant off at ground level and drag it back to the = water. What=20 they do not eat, they use for construction material in dams and lodges.=20

Benefits of Beavers
Beavers are=20 generally considered beneficial in situations where they do not compete = with=20 people for the use of the land, water or timber. Harvest of beaver pelts = may be=20 a source of income. While fur prices vary from year to year based on = fashion=20 trends, a recent survey done by the Kentucky Department of Fish and = Wildlife=20 Resources reported that more than 1,500 beaver pelts, valued at more = than=20 $20,000, were sold during the 1986-87 trapping season. Beaver ponds also = attract=20 a wide variety of other furbearing animals including mink, muskrat and = raccoon.=20 The value of these pelts, based on the same survey, was in excess of = $1.4=20 million.
The unique dam- and = pond-building attributes of beavers create favorable habitat for a = variety of=20 wildlife species, including fish, ducks, shorebirds, amphibians and = reptiles.=20 The variety of wildlife attracted to these ponds can be used for = recreational,=20 scientific or aesthetic purposes.
Ponds=20 created in beaver dams help stabilize water tables, reduce rapid runoff = from=20 heavy rainfall and reduce soil erosion by depositing silt in the pools. = Beaver=20 castoreum is used in numerous trapper's lures, perfumes and cosmetics. = Finally,=20 beaver meat is excellent table fare if properly prepared.=20

Damage Assessment
Most = beaver damage=20 is relatively easy to identify. Much of tiffs damage is associated with = or is a=20 result of dam building, bank burrowing, tree cutting or flooding. Spring = and=20 fall are the periods when landowners experience the most severe damage = from=20 beavers.
Damage in urban = areas includes=20 cutting or girdling of ornamental and shade trees or shrubs. Because = beavers are=20 rodents with large sharp incisors, damage to trees appears as clean, = knife-like=20 cuts at a 45-degree angle.
In rural=20 areas, beavers may dam drainage ditches and small streams and plug drain = pipes=20 or culverts. This can lead to localized flooding of roads, timber lands = or=20 agricultural cropland.
A = hazard=20 associated with beavers is giardiasis, a disease caused by a protozoan=20 (Giardia lamblia). This pathogenic intestinal parasite can be = carried by=20 beavers and transmitted to humans through the local water system. The = extent of=20 giardiasis is unknown in Kentucky, although some beavers with the = parasite have=20 been found in the state.=20

Prevention and Control of Beaver Problems
Beavers are classified as furbearing animals in the = state of=20 Kentucky. An open trapping season is established for the legal = harvesting of=20 these animals, and they are subject to all applicable state laws and=20 regulations. Consult the Kentucky Department of Fish and Wildlife's = trapping=20 digest for more information on removal of beavers during the legal = trapping=20 season.
If a beaver is = damaging your=20 property, you can kill the animal at times other than the legal trapping = season.=20 After the animal has been destroyed, you must contact your local = conservation=20 officer for disposal of the carcass.
If=20 the beaver pond has been in existence for a considerable period of time = (even if=20 it is flooded cropland), the area may be officially classified as a = wetland.=20 Under the provisions of the 1985 Food Security Act, Conservation Reserve = Provision, it may be illegal to destroy the dam and drain the wetland. = Contact=20 the U.S. Army Corps of Engineers in Louisville or your local = Agricultural and=20 Soil Conservation Service, Soil Conservation Service or Kentucky = Department of=20 Fish and Wildlife Resources office for an on-site visit and = recommendation.=20

Nonlethal Prevention and Control
Individual high-value shade or ornamental trees can = be=20 protected from beavers by wrapping them with 1/4- or 1/2-inch hardware = cloth to=20 a height of four feet. Small areas around culverts, drains and ponds in = urban=20 areas can be fenced using netwire with small mesh wire.
Another method of discouraging beavers is to install = a device=20 to manipulate the water level of a pond. This can be accomplished by = installing=20 a three-log drain (Figure 3) or wire mesh culvert that the beavers = cannot plug.=20 Lowering the water level in the summer encourages wild or planted foods = to grow,=20 providing excellent habitat and food for waterfowl.
For more information on constructing water control = structures=20 to discourage beavers and enhance waterfowl habitat, contact a Kentucky=20 Department of Fish and Wildlife Resources District biologist or the = Cooperative=20 Extension Service.
One = innovative way to=20 discourage beavers is the use of a high tensile electric fence (Figure = 4). Stake=20 a portable battery or solar-powered charging unit some distance from a = run=20 (slide) or a hole knocked into the dam. If you are placing the wire = across a=20 slide, mow or trim the vegetation very close to the ground. Finally, = string a=20 single strand of wire three inches above the ground or water's surface = so the=20 beavers will strike it as they pass through the slide or attempt to = repair the=20 hole in the dam. This electric shock acts to repel the animals; if they = are=20 shocked enough, they will move to another area.
Daily tearing out dams and removing dam construction = materials=20 with dynamite may cause a colony or individual beaver to move. This is = very=20 dangerous and not recommended. Even if this procedure is effective, the = beavers=20 may move into a new area and become even more troublesome.=20

Lethal Control
There are = no chemical=20 repellents or toxicants (poisons) registered for controlling beavers in=20 Kentucky. The only control method that works well is trapping. The most=20 effective trap is a number 330 Conibear (instant-kill-type) trap. This = trap is=20 designed to be placed underwater near a break in the dam, at the lodge = entrance,=20 near a slide or on a beaver run (Figure 5a), (Figure 5b), (Figure 5c), = (Figure=20 5d).Trapping should be done by an experienced trapper because these = traps exert=20 a tremendous pressure and impact when tripped. Therefore, appropriate = care must=20 be taken when setting and placing the trap.
The Kentucky Department of Fish and Wildlife = Resources, #1=20 Game Farm Road, Frankfort, KY 40601 provides technical guidance to = landowners=20 experiencing beaver problems. If the beaver problem is large in scope or = particularly severe, contact USDA-APHIS-ADC, 3231 Ruckriegel Parkway,=20 Louisville, KY 40299 for assistance.
It=20 is against the law in Kentucky to destroy or harm a beaver lodge or den. = Contact=20 the Kentucky Department of Fish and Wildlife Resources or USDA-APHIS-ADC = in=20 Louisville for technical guidance before destroying dams. =