B-1

BEAVERSJames E. MillerProgram Leader, Fish and WildlifeUSDA — Extension ServiceNatural Resources and Rural

Development UnitWashington, DC 20250

Greg K. YarrowExtension Wildlife SpecialistDepartment of Aquaculture, Fisheries,

and WildlifeClemson UniversityClemson, South Carolina 29634-0362

Fig. 1. Beaver, Castor canadensis

Damage Prevention andControl Methods

Exclusion

Fence small critical areas such asculverts, drains, or other structures.

Install barriers around important treesin urban settings.

Cultural Methods and HabitatModification

Eliminate foods, trees, and woodyvegetation where feasible.

Continually destroy dams andmaterials used to build dams.

Install a Clemson beaver pond leveler,three-log drain, or other structuraldevice to maintain a lower pondlevel and avoid further pondexpansion.

Frightening

Shooting of individuals or dynamitingor other continued destruction oflodges, bank dens, and dams,where legal, will occasionally moveyoung colonies out of an area.

Repellents

None are registered; however, there issome evidence that repellents maybe useful.

Toxicants

None are registered.

Trapping

No. 330 Conibear® traps.

Leghold traps No. 3 or larger(including coil-spring types withequivalent jaw spread and impact).

Basket/suitcase type traps areprimarily used for live trapping.

Snares can be useful, particularly indive sets and slides where legal.

Shooting

Rarely effective (where legal) forcomplete control efforts and can bedangerous to humans.

Other Methods

Other methods rarely solve a beaverdamage problem and may increaserisks to humans and nontargetspecies.

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994

Cooperative Extension DivisionInstitute of Agriculture and Natural ResourcesUniversity of Nebraska - Lincoln

United States Department of AgricultureAnimal and Plant Health Inspection ServiceAnimal Damage Control

Great Plains Agricultural CouncilWildlife Committee

B-2

Hind foot

Marks of webs not always distinct

Walking

3" to 6"

Tail mark

Fig. 2. Beaver tracksFront foot

6"

Fig. 3. A beaver uses its tail as a prop in order tosit upright.

Details of beaver cuttings.

Fig. 4. Range of the beaver in North America.

Identification

The beaver (Castor canadensis, Fig. 1) isthe largest North American rodent.Most adults weigh from 35 to 50pounds (15.8 to 22.5 kg), with someoccasionally reaching 70 to 85 pounds(31.5 to 38.3 kg). Individuals have beenknown to reach over 100 pounds (45kg). The beaver is a stocky rodentadapted for aquatic environments.Many of the beaver’s features enable itto remain submerged for long periodsof time. It has a valvular nose and ears,and lips that close behind the fourlarge incisor teeth. Each of the four feethave five digits, with the hind feetwebbed between digits and a splitsecond claw on each hind foot. Thefront feet are small in comparison tothe hind feet (Fig. 2). The underfur isdense and generally gray in color,whereas the guard hair is long, coarseand ranging in color from yellowishbrown to black, with reddish brownthe most common coloration. Theprominent tail is flattened dorso-ventrally, scaled, and almost hairless.It is used as a prop while the beaver issitting upright (Fig. 3) and for a rudderwhen swimming. Beavers also usetheir tail to warn others of danger byabruptly slapping the surface of thewater.The beaver’s large front (incisor)teeth, bright orange on the front, growcontinuously throughout its life. Theseincisors are beveled so that they arecontinuously sharpened as the beavergnaws and chews while feeding,girdling, and cutting trees. The onlyway to externally distinguish the sex ofa beaver, unless the female is lactating,is to feel for the presence of a baculum(a bone in the penis) in males and itsabsence in females.

Range

Beavers are found throughout NorthAmerica, except for the arctic tundra,most of peninsular Florida, and thesouthwestern desert areas (Fig. 4).The species may be locally abundantwherever aquatic habitats are found.

Habitat

Beaver habitat is almost anywherethere is a year-round source of water,such as streams, lakes, farm ponds,swamps, wetland areas, roadsideditches, drainage ditches, canals, minepits, oxbows, railroad rights-of-way,drains from sewage disposal ponds,and below natural springs or artesianwells. Beavers build dams to modifythe environment more to their liking.Dam building is often stimulated byrunning water. The length or height ofa dam generally depends upon what isnecessary to slow the flow of waterand create a pond. In areas of flat to-pography, the dam may not be over 36inches (0.9 m) high but as much as 1/4miles (0.4 km) long. In hilly or moun-tainous country, the dam may be 10feet (3 m) high and only 50 feet (15 m)long. Beavers are adaptable and willuse whatever materials are available toconstruct dams — fencing materials,bridge planking, crossties, rocks, wire,and other metal, wood, and fiber

Fig. 5. Cross section of a beaver lodge.

materials. Therefore, about the onlyavailable aquatic habitat beavers avoidare those systems lacking acceptablefoods, lodge or denning sites, or a suit-able dam site. Some of the surround-ing timber is cut down or girdled bybeavers to form dams. Subsequentflooding of growing timber causes it todie, and aquatic vegetation soon be-gins growing. Other pioneer species(for example, willow, sweetgum, andbuttonbush) soon grow around theedges of the flooded area, adding tothe available food supply. The beaverthus helps create its own habitat.

Food Habits

Beavers prefer certain trees andwoody species, such as aspen, cotton-wood, 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 woodyplants that grow near the water, aswell as a wide variety of herbaceousand aquatic plants. Beavers oftentravel 100 yards (90 m) or more from apond or stream to get to corn fields,soybean fields, and other growingcrops, where they cut the plants off atground level and drag them back tothe water. They eat parts of theseplants and often use the remainder asconstruction material in the dam.

General Biology,Reproduction, andBehavior

Beavers are active for approximately12 hours each night except on thecoldest of winter nights. The phrase“busy as a beaver” is appropriate. It isnot uncommon, however, to seebeavers during daylight hours, par-ticularly in larger reservoirs.

Beavers are generally monogamous;copulation may take place either in thewater or in the lodge or bank den.

After a gestation period of about 128days, the female beaver generally givesbirth to 3 or 4 kittens between Marchand June, and nurses them for 6weeks to 3 months. The kittens areborn fully furred with their eyes par-tially opened and incisors eruptedthrough the gums. They generallybecome sexually mature by the age of1 1/2 years.

Beaver communicate by vocalizations,posture, tail slapping, and scent postsor mud mounds placed around thebank and dam. The beaver’s castorglands secrete a substance that isdeposited on mud mounds to markterritorial boundaries. These scentposts are found more frequently atcertain seasons, but are found year-round in active ponds.

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B-4

Fig. 6. Pine plantation in Arkansas killed in flooding caused by beavers.

Beavers have a relatively long lifespan, with individuals known to havelived to 21 years. Most, however, donot live beyond 10 years. The beaver isunparalleled at dam building and canbuild dams on fast-moving streams aswell as slow-moving ones. They alsobuild lodges and bank dens, depend-ing on the available habitat. All lodgesand bank dens have at least two en-trances and may have four or more.The lodge or bank den is used prima-rily for raising young, sleeping, andfood storage during severe weather(Fig. 5).

The size and species of trees the beavercuts is highly variable — from a 1-inch(2.5-cm) diameter at breast height(DBH) softwood to a 6-foot (1.8-m)DBH hardwood. In some areas bea-vers usually cut down trees up toabout 10 inches (25 cm) DBH andmerely girdle or partially cut largerones, although they often cut downmuch larger trees. Some beavers seemto like to girdle large pines and sweet-gums. They like the gum or storax thatseeps out of the girdled area of sweet-gum and other species.

An important factor about beavers istheir territoriality. A colony generallyconsists of four to eight related bea-vers, who resist additions or outsidersto the colony or the pond. Young bea-vers are commonly displaced from thecolony shortly after they become sexu-ally mature, at about 2 years old. Theyoften move to another area to begin anew pond and colony. However, somebecome solitary hermits inhabiting oldabandoned ponds or farm ponds ifavailable.

Beavers have only a few natural preda-tors aside from humans, includingcoyotes, bobcats, river otters, andmink, who prey on young kittens. Inother areas, bears, mountain lions,wolves, and wolverines may prey onbeavers. Beavers are hosts for severalectoparasites and internal parasites in-cluding nematodes, trematodes, andcoccidians. Giardia lamblia is a patho-genic intestinal parasite transmitted bybeavers, which has caused humanhealth problems in water supply sys-

tems. The Centers for Disease Controlhave recorded at least 41 outbreaks ofwaterborne Giardiasis, affecting morethan 15,000 people. For more informa-tion about Giardiasis, see vonOettingen (1982).

Damage and DamageIdentification

The habitat modification by beavers,caused primarily by dam building, isoften beneficial to fish, furbearers,reptiles, amphibians, waterfowl, andshorebirds. However, when this modi-fication comes in conflict with humanobjectives, the impact of damage mayfar outweigh the benefits.

Most of the damage caused by beaversis a result of dam building, bank bur-rowing, tree cutting, or flooding. Somesoutheastern states where beaver dam-age is extensive have estimated thecost at $3 million to $5 million dollarsannually for timber loss; crop losses;roads, dwellings, and flooded prop-erty; and other damage. In somestates, tracts of bottomland hardwoodtimber up to several thousand acres(ha) in size may be lost because of bea-ver. Some unusual cases observed

include state highways floodedbecause of beaver ponds, reservoirdams destroyed by bank den burrowscollapsing, and train derailmentscaused by continued flooding and bur-rowing. Housing developments havebeen threatened by beaver dam flood-ing, and thousands of acres (ha) ofcropland and young pine plantationshave been flooded by beaver dams(Fig. 6). Road ditches, drain pipes, andculverts have been stopped up sobadly that they had to be dynamitedout and replaced. Some bridges havebeen destroyed because of beaverdam-building activity. In addition,beavers threaten human health bycontaminating water supplies withGiardia.

Identifying beaver damage generally isnot difficult. Signs include dams;dammed-up culverts, bridges, or drainpipes resulting in flooded lands, tim-ber, roads, and crops; cut-down orgirdled trees and crops; lodges andburrows in ponds, reservoir levees,and dams. In large watersheds, it maybe difficult to locate bank dens. How-ever, the limbs, cuttings, and debrisaround such areas as well as damsalong tributaries usually help pinpointthe area.

Legal Status

The legal status of beavers varies fromstate to state. In some states the beaveris protected except during furbearerseasons; in others it is classified as apest and may be taken year-roundwhen causing damage. Because of itsfur value, dam building, and resultingwater conservation, it is generally notconsidered a pest until economiclosses become extensive. Fur prices forbeaver in some states, particularly inthe Southeast, make it hardly worththe skinning and stretching. In somenorthern states, trapping is prohibitednear lodges or bank dens to protectand perpetuate beaver colonies. Furprices for beaver pelts are usuallymuch higher in these areas.

Damage Prevention andControl Methods

Exclusion

It is almost impossible as well as cost-prohibitive to exclude beavers fromponds, lakes, or impoundments. If theprimary reason for fencing is toexclude beavers, fencing of large areasis not practical. Fencing of culverts,drain pipes, or other structures cansometimes prevent damage, but fenc-ing can also promote damage, since itprovides beavers with constructionmaterial for dams. Protect valuabletrees adjacent to waterways by encir-cling them with hardware cloth,woven wire, or other metal barriers.Construction of concrete spillways orother permanent structures mayreduce the impact of beavers.

Cultural Methods

Because beavers usually alter ormodify their aquatic habitat so exten-sively over a period of time, mostpractices generally thought of as cul-tural have little impact on beavers.Where feasible, eliminate food, trees,and woody vegetation that is adjacentto beaver habitat. Continual destruc-tion of dams and removal of damconstruction materials daily will(depending on availability of construc-tion materials) sometimes cause a

colony or individual beavers to moveto another site. They might, however,be even more troublesome at the newlocation.

The use of a three-log drain or a struc-tural device such as wire mesh cul-verts (Roblee 1983) or T-culvert guards(Roblee 1987) will occasionally causebeavers to move to other areas. Theyall prevent beavers from controllingwater levels. However, once beavershave become abundant in a watershedor in a large contiguous area, periodicreinvasions of suitable habitat can beexpected to occur. Three-log drainshave had varying degrees of success incontrolling water levels in beaver im-poundments, especially if the beavercan detect the sound of falling water orcurrent flow. All of these devices willstimulate the beavers to quickly plugthe source of water drainage.

A new device for controlling beaverimpoundments and keeping blockedculverts open is the Clemson beaverpond leveler. It has proven effective inallowing continual water flow in previ-ously blocked culverts/drains andfacilitating the manipulation of waterlevels in beaver ponds for moist-soilmanagement for waterfowl (Woodand Woodward 1992) and other envi-ronmental or aesthetic purposes. Thedevice (Fig. 7) consists of a perforatedPVC pipe that is encased in heavy-gauge hog wire. This part is placedupstream of the dam or blocked cul-vert, in the main run or deepest part ofthe stream. It is connected to nonper-forated sections of PVC pipe which arerun through the dam or culvert to awater control structure downstream. Itis effective because the beavers cannotdetect the sound of falling or flowingwater as the pond or culvert drains;therefore, they do not try to plug thepipe. The Clemson beaver pond lev-eler works best in relatively flat terrainwhere large volumes of water fromwatersheds in steep terrain are not aproblem.

Repellents

There are no chemical repellents regis-tered for beavers. Past research effortshave tried to determine the effective-

ness of potential repellent materials;however, none were found to be effec-tive, environmentally safe, or practical.One study in Georgia (Hicks 1978)indicated that a deer repellent hadsome potential benefit. Other studieshave used a combination of dam blow-ing and repellent soaked (Thiram 80and/or paradichlorobenzene) rags todiscourage beavers with varyingdegrees of success (Dyer and Rowell1985).

Additional research is needed onrepellents for beaver damage preven-tion.

Toxicants

None are registered. Research effortshave been conducted, however, to findeffective, environmentally safe andpractical toxicants. Currently there arenone that meet these criteria.

Fumigants

None are registered.

Trapping

The use of traps in most situationswhere beavers are causing damage isthe most effective, practical, and envi-ronmentally safe method of control.The effectiveness of any type of trapfor beaver control is dependent on thetrapper’s knowledge of beaver habits,food preferences, ability to read beaversigns, use of the proper trap, and trapplacement. A good trapper with adozen traps can generally trap all thebeavers in a given pond (behind onedam) in a week of trap nights. Obvi-ously in a large watershed with severalcolonies, more trapping effort will berequired. Most anyone with trappingexperience and some outdoor “savvy”can become an effective beaver trapperin a short time. In an area where bea-vers are common and have not beenexposed to trapping, anyone experi-enced in trapping can expect good suc-cess. Additional expertise andimproved techniques will be gainedthrough experience.

A variety of trapping methods andtypes of traps are effective for beavers,depending on the situation. Fish andwildlife agency regulations vary from

B-5

B-6

Elbow and stand pipe are optional.Needed only to manage water level ifmaintaining pond is an objective.

1" re-bar6' long

8" diameter 40 PVC pipe

T - joint tilted with a drain plugmay replace elbow.

Pond side

20'

Table 1. List of materials for the Clemson Beaver Pond Leveler.

Quantity Item

1 .................................. 10' section, 10" diameter PVC pipe (Schedule 40)1 .................................. PVC cap for 10" diameter PVC pipe (Schedule 40)1 .................................. 10" x 8" PVC pipe reducer coupling (Schedule 40)4 .................................. 86" sections, 3/4" diameter plastic roll pipe (water pipe), 160 psi grade4 .................................. 3/4" metal couplings for roll pipe

16 .................................. 1/4" x 2" galvanized eyebolts16 .................................. 1/4" galvanized nuts16 .................................. 1/4" galvanized washers16 .................................. 16" sections, 8 gauge galvanized wire (medium hardness)2 .................................. 96" sections, 2" x 4" 1/2 gauge galvanized welded wire

2 lbs .................................. Crab trap clamps (fasteners)

The above materials are required to assemble the intake device. The carrying pipe (flow pipe) may consist of 20 to 40 feet of8-inch diameter PVC, Schedule 40 with coupling sleeves and elbows appropriate to the desired configuration.

Fig. 7. Clemson beaver pond leveler.

Intakedevice

Beaverdam

state to state. Some types of traps andtrapping methods, although effectiveand legal in some states, may beprohibited by law in other states.Individual state regulations must bereviewed annually before beginning atrapping program

In some states where beavers havebecome serious economic pests, specialregulations and exemptions have beenpassed to allow for increased controlefforts. For example, some states allowtrapping and snaring of beavers andother control measures throughout the

year. Others, however, prohibit trap-ping except during established furtrapping seasons. Some states allowexemptions for removal of beaversonly on lands owned or controlled bypersons who are suffering losses. Insome states a special permit isrequired from the state fish and wild-life agency.

Of the variety of traps commonlyallowed for use in beaver control, theConibear® type, No. 330, is one of themost effective (Fig. 8). Not all trapperswill agree that this type of trap is the

most effective; however, it is the typemost commonly used by professionaltrappers and others who are princi-pally trapping beavers. This trap killsbeavers almost instantly. When prop-erly set, the trap also prevents anyescape by a beaver, regardless of itssize. Designed primarily for water use,it is equally effective in deep and shal-low water. Only one trap per site isgenerally necessary, thus reducing theneed for extra traps. The trap exertstremendous pressure and impactwhen tripped. Appropriate care mustbe exercised when setting and placing

Fig. 8. Basic method of setting and staking aConibear® 330 trap. Additional stakes arenormally used (see Fig. 9).

Dive stick

Fig. 9. Conibear trap in dive set.

Run

Levee

EntranceFig. 10. Runs or underwater entrances to lodgesare good places to set beaver traps.

the trap. Care should also be takenwhen using the Conibear® type trapsin urban and rural areas where pets(especially dogs) roam free. Use trapsets where the trap is placed com-pletely underwater.

Some additional equipment will beuseful: an axe, hatchet, or large cuttingtool; hip boots or waders; wire; andwire cutters. With the Conibear®-typetrap, some individuals use a device or

tool called “setting tongs.” Others usea piece of 3/8- or 1/2-inch (9- or 13-mm) nylon rope. Most individualswho are experienced with these trapsuse only their hands. Regardless of thetechniques used to set the trap, careshould be exercised.

Earlier models of the Conibear® typeof trap came with round, heavy steelcoils which were dangerous to handleunless properly used in setting the

trap. They are not necessary to safelyset the trap. However, the two safetyhooks, one on each spring, must becarefully handled as each spring isdepressed, as well as during trapplacement. On newer models an addi-tional safety catch (not attached to thesprings) is included for extra precau-tion against inadvertent spring release.The last step before leaving a set trap isto lift the safety hook attached to eachspring and slide the safety hook backfrom the trap toward the spring eye,making sure to keep hands and feetsafely away from the center of the trap.If the extra (unattached) safety catch isused, it should be removed before thesafety hooks that are attached to thesprings to keep it from getting in theway of the movement of the safetyhooks.

Conibear®-type traps are best set whileon solid ground with dry hands. Oncethe springs are depressed and thesafety hooks in place, the trap or trapscan be carried into the water forproper placement. Stakes are neededto anchor the trap down. In most bea-ver ponds and around beaver dams,plenty of suitable stakes can be found.At least two strong stakes, preferablystraight and without forks or snags,should be chosen to place througheach spring eye (Fig. 8). Additionalstakes may be useful to put betweenthe spring arms and help hold the trapin place. Do not place stakes on theoutside of spring arms. Aside fromserving to hold the trap in place, thesestakes also help to guide the beaverinto the trap. Where needed, they arealso useful in holding a dive stick at orjust beneath the water surface (Fig. 9).If necessary, the chain and circleattached to one spring eye can beattached to another stake. In deepwater sets, a chain with an attachedwire should be tied to something at orabove the surface so the trapper canretrieve the trap. Otherwise the trapmay be lost.

Trap Sets. There are many sets that canbe made with a Conibear®-type trap(for example, dam sets, slide sets,lodge sets, bank den sets, “run”/trailsets, under log/dive sets, pole sets,under ice sets, deep water sets, drain

B-7

B-8

Fig. 11. Dam set. Set the trap underwater infront of the hole created in the dam. When thebeaver returns to patch the hole, it will becaught in the trap.

Hole torn through dam to release water.

Beaver dam

Fig. 12. Leghold trap (No. 3 or No. 4, doublespring) attached to wire for drowning set.

Dig out slide under water to accept trap andsprings.

Slide wire fastened tostake and weight.

Fig. 13. Leghold trap in slide set.

pipe sets), depending on the trapper’scapability and ingenuity. In many bea-ver ponds, however, most beavers canbe trapped using dam sets, lodge orbank den sets, sets in “runs”/trails,dive sets or sets in slides entering thewater from places where beavers arefeeding. Beavers swim both at the sur-face or along the bottom of ponds, de-pending on the habitat and waterdepth. Beavers also establish runs ortrails which they habitually use in trav-eling from lodge or den to the dam orto feeding areas, much like cow trailsin a pasture.

Place traps directly across these runs,staked to the bottom (Fig. 10).

Use a good stake or “walking staff’when wading in a beaver pond tolocate deep holes, runs, or trails. Thiswill prevent stepping off over wadersor hip boots in winter, and will helpward off cottonmouth snakes in thesummer. The staff can also help locategood dive holes under logs as youwalk out runs or trails. In older beaverponds, particularly in bottomlandswamps, it is not uncommon to findruns and lodge or bank den entranceswhere the run or hole is 2 to 3 feet (0.6to 0.9 m) below the rest of the im-poundment bottom.

To stimulate nighttime beaver move-ment, tear a hole in a beaver dam andget the water moving out of a pond.Beavers quickly respond to the soundof running water as well as to the cur-rent flow. Timing is also important ifyou plan to make dam sets. Open ahole in the dam about 18 inches to 2feet (46 to 60 cm) wide and 2 to 3 feet(60 to 90 cm) below the water level onthe upper side of the dam in the morn-ing. This will usually move a substan-tial amount of water out of the pondbefore evening (Fig. 11). Set traps infront of the dam opening late thatsame evening. Two problems can ariseif you set a trap in the morning as soonas a hole is made: (1) by late evening,when the beavers become active, thetrap may be out of the water and inef-fective; or (2) a stick, branch, or otherdebris in the moving water may tripthe trap, again rendering it ineffective.

The best dam sets are made about 12to 18 inches (30.8 to 45.7 cm) in front ofthe dam itself. Using stakes or debrison either side of the trap springs,create a funnel to make the beaver gointo the jaws of the trap. Always setthe trigger on the Conibear®-type trapin the first notch to prevent debrisfrom tripping it before the beaverswims into the trap. The two heavy-gauge wire trippers can be bent out-ward and the trigger can be set awayfrom the middle if necessary, to keepdebris from tripping the trap. This canalso keep small beaver or possibly fishor turtles from springing the trap.

Double-spring leghold traps have beenused for hundreds of years and arestill very effective when properly usedby skilled trappers. Use at least No. 3double (long) spring or coil spring typeleghold traps or traps of equivalentsize jaw spread and strength. Use adrowning set attachment with anyleghold trap (Fig. 12). As the traps aretripped, the beaver will head for thewater. A weight is used to hold thetrapped beaver underwater so that itultimately drowns. Some trappersstake the wire in deep water to accom-plish drowning. If leghold traps arenot used in a manner to accomplishdrowning, there is a good likelihoodthat legs or toes will be twisted off orpulled loose, leaving an escaped, trap-wise beaver.

Placement is even more critical withleghold traps than with the Conibear®-type. Place leghold traps just at thewater’s edge, slightly underwater,with the pan, jaws, and springs cov-ered lightly with leaves or debris orpressed gently into the pond bottom insoft mud. Make sure there is a cavityunder the pan so that when thebeaver’s foot hits the pan, it will trig-ger the trap and allow the jaws to snapclosed. Place traps off-center of thetrail or run to prevent “belly pinching”or missing the foot or leg. With someexperience, beaver trappers learn tomake sets that catch beavers by a hindleg rather than a front leg. The frontleg is much smaller and easier to twistoff or pull out.

Sometimes it’s wise, when usingleghold traps, to make two sets in aslide, run, dam, or feeding place toincrease trapping success and removebeavers more quickly. In some situa-tions, a combination of trappingmethods can shorten trapping timeand increase success.

Trappers have come up with uniquemethods of making drown sets. One ofthe simplest and most practical is aslide wire with a heavy weightattached to one end, or with an endstaked to the bottom in 3 or more feet(>0.9 m) of water. The other end of thewire is threaded through a hole in oneend of a small piece of angle iron. Thetrap chain is attached to a hole in theother end of the angle. The end of thewire is then attached to a tree or stakedriven into the bank (Fig. 13). Whenthe beaver gets a foot or leg in the trap,it immediately dives back into thewater. As the angle slides down thewire, it prevents the beaver fromreaching the surface. The angle ironpiece will not slide back up the wireand most often bends the wire as thebeaver struggles, thus preventing thebeaver from coming up for air. Trap-pers should be prepared to quicklyand humanely dispatch a beaver thatis caught in a trap and has notdrowned.

The leghold trap set in lodges or bankdens is also effective, especially fortrapping young beavers. Place the seton the edge of the hole where the bea-ver first turns upward to enter thelodge or den, or place it near the bot-tom of the dive hole. Keep the jawsand pan off of the bottom by pullingthe springs backward so that a swim-ming foot will trip the pan. Stake theset close to the bottom or wire the trapto a log or root on the bottom, to avoidthe need for drowning weights, wires,and angle iron pieces. Generally, moretime and expertise is necessary tomake effective sets with leghold trapsand snares than is required with theConibear®-type trap.

Use scent or freshly cut cottonwood,aspen, willow, or sweetgum limbs toentice beaver to leghold trap sets. Baitor scent is especially useful aroundscent mounds and up slides along thebanks or dams. Most trappers who useConibear®-type traps do not employbaits or scent, although they are occa-sionally helpful. In some states it is ille-gal to use bait or scent.

Several other types of traps can beused, including basket/suitcase typelive traps. These are rarely used, how-ever, except by professionals in urbanareas where anti-trap sentiment orother reasons prevent the killing ofbeavers. These traps are difficult andcumbersome to use, and will not befurther discussed here for use in bea-ver damage control. Any type of trapsused for beavers or other animalsshould be checked daily.

Snaring can be a very cost-effectivemethod for capturing beavers. Snaringequipment costs far less than trappingequipment and is more convenient touse in many situations. In addition,beavers can be captured alive by snar-ing and released elsewhere if desired.

Snare placement is similar to trapplacement. First, look for runways andfresh sign that indicate where beaveractivities are focused. Find a suitableanchor such as a large tree, log, or rootwithin 10 feet (3 m) of the runwaywhere the snare will be set. If neces-sary, anchor snares by rods driven intothe ground, but this is more time con-suming and less secure. Attach three14-gauge wires to the anchor so thateach can swivel freely. Cut each wireto length so they reach about 1 foot (30cm) past the runway. Twist the wirestogether to form a strong braidedanchor cable. Drive a supporting stakeinto the ground near the runway andwrap the free end of the anchor cablearound it twice. Prepare a new, dyed,No. 4 beaver or coyote snare, consist-ing of 42 inches (107 cm) of 3/32-inch(2.4-mm) steel cable with an attachedwire swivel and slide lock. Twist thefree ends of the three anchor wiresaround the wire swivel on the end of

B-9

B-10

Fig. 14. Conibear® in culvert set. When beaversare stopping up a drainage culvert, (1) clean outthe pipe to get water flowing through freely; (2)set the trap at the level of the drain pipeentrance, but far enough away to clear theculvert when the beaver enters; (3) put stakeson either side to make the beaver enter the trapcorrectly.

the snare cable. Wrap the longest an-chor wire around the base of the wireswivel and crimp it onto the snarecable about 2 inches (5 cm) from theswivel. Use both the stake and the sup-porting anchor wire to suspend a full-sized loop about 4 inches (10 cm)above the runway. If necessary, useguide sticks or other natural debris toguide beaver into the snare.

The described snare set is very com-mon, but there are several variationsand sets that can be used. Snares arefrequently placed under logs, nearbank dens, and next to castor mounds.Drowning sets can be made using un-derwater anchors, slide cables, andslide locks.

Snares should be checked at least ev-ery 24 hours. Dispatch snared beaverswith a sharp blow or shot to the head.Beavers can be chemically immobi-lized and transported to suitable sitesfor release if desired.

Snares must be used with great care toavoid capturing nontarget animals.Avoid trails or areas that are used bylivestock, deer, or dogs. Check withyour local wildlife agency for regula-tions associated with trapping andsnaring. Snaring is not allowed insome states.

For more information about the use ofsnares see A Guide to Using Snares forBeaver Capture (Weaver et al. 1985)listed at the end of this chapter.

Shooting

In some states, because of the extent ofdamage caused by beavers, regula-tions have been relaxed to allow shoot-ing. Some states even allow the use ofa light at night to spot beavers whileshooting. Before attempting to shootbeavers, check regulations, and ifapplicable, secure permits and notifylocal law enforcement personnel ofyour intentions.

Beavers are most active from late after-noon to shortly after daybreak,depending on the time of year. Theyusually retire to a lodge or bank denfor the day. Therefore, if night shoot-ing is not permitted, the early eveningand early morning hours are most

productive. Choice of weaponsdepends on the range and situation.Most shooting is done with a shotgunat close range at night. Shooting aloneis generally not effective in eliminatingall beaver damage in an area. It can,however, be used to quickly reduce apopulation.

Other Methods

Because of the frustration and damagebeavers have caused landowners,almost every control method imagin-able has been tried. These range fromdynamiting lodges during midday tousing snag-type fish hooks in front ofdams, road culverts, and drain pipes.Such methods rarely solve a damageproblem, although they may kill a fewbeavers and nontarget species. Theyare not recommended by responsiblewildlife professionals. One methodused occasionally along streams proneto flooding is shooting beavers thathave been flooded out of lodges andbank dens. This method is often dan-gerous and rarely solves a damageproblem.

Economics of Damageand Control

The economics of beaver damage issomewhat dependent on the extent ofthe damage before it has been dis-covered. Some beaver damage prob-lems are intensive, such as damage

caused by one or two beavers in a newpond, damming or stopping up a cul-vert or drain pipe, flooding roads, orcrops. Other problems are extensive,such as several beaver colonies in aflatland area, responsible for the flood-ing of several hundred acres of mar-ketable timber that will die unless thewater is removed quickly. Generallyspeaking, if a culvert or drain pipe canbe unstopped, a knowledgeable trap-per can remove one or two beavers ina night or two and eliminate furtherdamage in an intensive damage situa-tion (Fig. 14). However, an extensivesituation may require a concentratedeffort with several trappers,dynamiting or pulling dams, and amonth or more of trapping to get thewater off the timber and reduce fur-ther timber losses.

Economic damage is estimated to haveexceeded $40 billion in the South-eastern United States during a recent40-year period (Arner and Dubose1982). This would include all damageto crops, forests, roads, pastures, andother rural and urban properties.

Economically, one must assess thesituation and weigh the tradeoffs: thepotential loss of thousands of boardfeet of timber and years of regenera-tion versus the cost of trapping. Thecost of a couple of nights’ trapping anda half-day of labor to clear the culvertsis much less than the cost of rebuildinga washed-out road or losing floodedcrops or timber.

The most important point is that dam-age control should begin as soon as itis evident that a beaver problem existsor appears likely to develop. Once bea-ver colonies become well establishedover a large contiguous area, achievingcontrol is difficult and costly. One ofthe most difficult situations ariseswhen an adjacent landowner will notallow the control of beavers on theirproperty. In this situation, one canexpect periodic reinvasions of beaversand continual problems with beaverdamage, even if all beavers areremoved from the property wherecontrol is practiced.

Although benefits of beavers and bea-ver ponds are not covered in depthhere, there are a number. Aside fromcreating fish, waterfowl, furbearer,shorebird, reptile, and amphibian habi-tat, the beaver in many areas is animportant fur resource, as well as afood resource. For those who have notyet tried it, beaver meat is excellenttable fare if properly prepared, and itcan be used whether the pelts areworth skinning or not. It also makesgood bait for trapping large predators.

Proper precautions, such as wearingrubber gloves, should be taken whenskinning or eviscerating beaver car-casses, to avoid contracting transmis-sible diseases such as tuleremia.

Acknowledgments

The authors thank, for their cooperation, pastand present employees of the Fish and WildlifeService, US Department of the Interior, countyextension agents with the CooperativeExtension Service in various states, cooperatorswith the USDA-APHIS-ADC program in anumber of states, and the many landownerswith beaver problems across the South. Theexperience gained in efforts to assist landownerswith wildlife damage problems provided mostof the information contained herein.

Figures 1, 2, 4 and 5 from Schwartz andSchwartz (1981).

Figure 3 by Jill Sack Johnson.

Figure 6 and 7 by the authors.

Figures 8 through 12 and 14 from Miller (1978).

Figure 13 by Jill Sack Johnson after Miller (1978).

For AdditionalInformation

Arner, D. H., and J. S. Dubose. 1982. The impactof the beaver on the environment andeconomics in Southeastern United States.Trans. Int. Congr. Game Biol. 14:241-247.

Byford, J. L. 1976. Beavers in Tennessee: control,utilization and management. TennesseeCoop. Ext. Serv., Knoxville. Pub. 687. 15 pp.

Dyer, J. M., and C. E. Rowell. 1985. Aninvestigation of techniques used todiscourage rebuilding of beaver damsdemolished by explosives. Proc. EasternWildl. Damage Control Conf. 2:97-102.

Hicks, J. T. 1978. Methods of beaver control.Final Rep., Res. Proj. No. W-37-R, GeorgiaGame Fish Div., Dep. Nat. Res. 3 pp.

Hill, E. H. 1974. Trapping beaver and processingtheir fur. Alabama Coop. Wildl. Res. Unit,Agric. Exp. Stn., Auburn Univ. Pub. No. 1.10 pp.

Miller, J. E. 1972. Muskrat and beaver control.Proc. Nat. Ext. Wildl. Workshop, 1:35-37.

Miller, J. E. 1978. Beaver — friend or foe.Arkansas Coop. Ext. Serv., Little Rock. Cir.539. 15 pp.

Roblee, K. J. 1983. A wire mesh culvert for use incontrolling water levels at nuisance beaversites. Proc. Eastern Wildl. Damage ControlConf. 1:167-168.

Roblee, K. J. 1987.The use of the T-culvert guardto protect road culverts from pluggingdamage by beavers. Proc. Eastern Wildl.Damage Control Conf. 3:25-33

Schwartz, C. W., and E. R. Schwartz. 1981. Thewild mammals of Missouri, Rev. ed. Univ.Missouri Press, Columbia. 356 pp.

von Oettingen, S.L. 1982. A survey of beaver incentral Massachusetts for Giardia lamblia.M.S. Thesis, Univ. Massachusetts, Amherst.58 pp.

Weaver, K. M., D. H. Arner, C. Mason, and J. J.Hartley. 1985. A guide to using snares forbeaver capture. South. J. Appl. For. 9(3):141-146.

Wood, G. W., and L. A. Woodward. 1992. TheClemson beaver pond leveler. Proc. Annu.Conf. Southeast Fish Wildl. Agencies.

EditorsScott E. HygnstromRobert M. TimmGary E. Larson

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