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The beaver (Castor canadensis) is the largest rodent found in North America. Its appearance is similar to that of a large muskrat with a broad, flattened tail. Most adults weigh between 30 and 70 pounds and measure about 4 feet in length. Like other rodents, the beaver’s front teeth (incisors) grow throughout its life. The back surface of their incisors is softer than the front surface so that when they gnaw, the teeth are constantly sharpened and maintain a chisel-like appearance. The beaver’s front feet, although not webbed, are skillfully used for digging, grooming and carrying objects. Their large hind feet are fully webbed and aid in swimming. A unique feature of the beaver is that the second toenail of each hind foot is double or split and is used as a comb to groom its fur.
Of course, the most unusual part of the beaver is its tail. The tail is used for many functions but is seldom used as a trowel for carrying mud. The tail is used as a rudder and a propulsion agent during swimming, and it supports the body when cutting trees. One of its main functions is a signaling device. When startled, the broad, flat tail is smacked on the surface of the water, alerting other beaver in the area of possible danger. Beavers dive under water to escape danger and can remain submerged for up to six minutes before resurfacing for air.
These “engineers of the wilderness” are best known for their abilities to cut down trees and construct dams. Indiana beaver restrict most of the cuttings to brush and small saplings, although they are capable of felling large trees. In cutting a tree, a beaver turns its head sideways and anchors its upper teeth into the tree. Then, by bringing up its lower teeth and twisting its head, the beaver tears out a large chip. It continues working around the tree, cutting a deeper and wider swath until the tree topples.
Although all beavers are capable of building lodges, many in Indiana build a modified bank burrow. One or two tunnels lead from below water level up into the bank to a nest chamber above water level. The nest chamber is about 2 feet high and 4 to 6 feet in diameter. Frequently, a pile of interlaced sticks and branches mixed with mud is placed on top of the bank directly above the nest chamber.
Beavers are strict vegetarians. During the winter months, their diet consists primarily of the bark and twigs of trees and other woody plants. Before winter arrives, beavers eagerly fell trees. Each branch is clipped from the main log, cut in appropriate size and then stashed under water in a large brushpile. When ice covers the water surface, food is readily available by swimming from the lodge to the brushpile. During the spring and summer, beaver feed on both leafy parts and roots of aquatic plants such as cattail, duck potato, water lily, spadderdock, grass and sedge. Beavers are also very fond of young blackberry canes; and when cornfields are nearby, large quantities of corn may also be appropriated.
Distribution and Abundance
More than 8,000 miles of flowing water and thousands of acres of lakes and ponds are available in Indiana for beaver to inhabit. Beavers have few enemies, and predation is limited primarily to man. Because they live in small, isolated colonies and are intolerant of newcomers, disease is not spread and has little effect in depressing population growth. It is estimated that without controls, the beaver population would increase by about one-third each year.
Prevention and Control
Resident landowners and tenants can trap or shoot a beaver that is causing damage on their own property without a permit from the DNR. The beaver must be euthanized or released within the county of capture on property in which you have permission. In order to prevent the spread of disease, the DNR encourages homeowners to safely and humanely euthanize beavers, if possible. If you do not want to trap the beaver yourself, contact a licensed nuisance wild animal control operator.
It is almost impossible or cost-prohibitive to exclude beavers from large ponds, lakes or impoundments. Fencing of culverts, drain pipes and other structures can sometimes be effective. Three-log drains, T-culvert guards, and the Clemson beaver pond lever have proven effective in certain situations. You can protect valuable trees adjacent to waterways by encircling them with hardware cloth, woven wire, or other metal barriers. Where feasible, eliminating food, trees, and woody vegetation adjacent to areas where beavers are found.
Trapping beavers in most situations is the most effective and practical method of control. Legal body-gripping traps and snares can be used in the water. Foot-hold traps in lodges or bank dens can also be effective. Live cage-traps are often not as effective for capturing beavers.
Shooting, if done in a safe manner where legal, can also be effective means of controlling beavers, particularly if done in the early evening, early morning, or nighttime hours.
Beaver lodges cannot be removed without a permit from the DNR Division of Fish and Wildlife. Beaver dams can be removed, but the use of explosives and or heavy machinery will require a permit from the DNR for their removal.