Beavers

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Because of its valuable fur, the beaver played an important role in the settlement of North America. In fact, Chicago was a busy fur-trading center in the 17th and 18th centuries. So popular were the beaver’s flesh, fur and leathery tail that by the early 1900s, the animal was extinct in Illinois.

Ecologists made attempts between 1929 and 1936 to reintroduce the beaver in Illinois, and by 1954, beavers again lived in almost half the counties in the state. Today, they make their homes in many local rivers, streams and lakes.

Habits and Habitat

Dams are important elements of the beaver’s survival. They are constructed of tree branches that the beaver cuts and then stabilizes with rocks and mud. A dammed stream becomes a pond that provides the beaver with drinking water, a travel route and shelter.

A beaver colony is made up of one family unit. Each family consists of a lifelong mated pair and offspring from two succeeding breeding seasons. There are usually four beavers in the spring-born litters. At two years of age, the offspring leave the colony and seek their own homes, thereby spreading the population along waterways and recolonizing vacant habitat.

Colony members usually construct a lodge, a dome-shaped home of branches and mud in the water. The lodge, sometimes rising 5 feet above the water, is warm and dry inside and is accessible through underwater passages. Beavers may also dig a tunnel and den in a riverbank or lakeshore.

Most active after sundown, beavers are strict vegetarians and will eat tender twigs, the roots of aquatic plants, marsh grasses and corn. Favorite tree barks include cottonwood, willow, aspen, birch and poplar. Beavers store their winter food supply under water, anchoring large groups of branches and twigs into muddy pond bottoms around their lodges.

Identification

At 40 to 60 pounds, the beaver is one of the largest aquatic rodents. A full-grown beaver is about 4 feet long, including its foot-long tail. Its body is stocky with short legs, sharp front claws and webbed feet. Its glossy coat is tan to dark brown with coarse overhair and a fine, dense underfur. 

The beaver’s trademark is its large front teeth. Two lower and two ever-growing upper incisors are essential tools for the animal’s activities.

The marks made by the beaver’s sharp teeth can be seen as smooth cuts in the wood. Once a tree is cut down, the beaver will eventually gnaw it into portable pieces, eat the bark from the trunk and branches and move the branches to the nearby waterway.

Telltale signs of a beaver’s presence are a dam, conical-shaped tree stumps and diagonally cut branches.

Recommended Deterrents

Light, inexpensive wire fencing with a minimum height of 3 feet is the simplest long-term solution for keeping beavers out of waterside property or to protect clusters of trees. The lower 3 feet of individual trees can also be wrapped with heavy-gauged hardware cloth. Remember to loosen the wire as the tree grows.

Flooding due to beavers in DuPage County forest preserves is not controlled by the Forest Preserve District of DuPage County unless it causes a public danger. However, if a beaver dam in a forest preserve is causing flooding upstream on private property, the District may regulate the water levels by placing a drain pipe in the dam to control the water levels.

What Not To Do

  • Trapping and removing a beaver is not always the solution to the problem. Removing the animal is illegal without the proper permits and only creates an open space for another animal. A trapped adult may also leave young behind to die of starvation in an inaccessible area. Focus on removing the attraction, not the animal.
  • Never move young from the lodge. 
  • Destroying a beaver dam will not discourage these tenacious animals. They will build a new one, seemingly overnight. A beaver will eventually move only if you are more persistent at tearing down the dam than it is at rebuilding it.
  • Do not use poisons. They are inhumane and may be illegal. They can also result in secondary poisoning of raptors, wild scavengers and neighborhood pets.
  • It is illegal to keep wild animals, even for a short time. They have specialized nutritional, housing and handling needs that you are unlikely to be able to provide. Inexperienced individuals who attempt to raise or treat them inevitably produce unhealthy, tame animals that cannot survive in their natural habitats.

Public Health Concerns

Beavers are known to carry giardia, a parasite that causes severe diarrheal illness. Pets and humans can become infected after swallowing water that contains the parasite and, therefore, should not drink water where beavers may be present.

Willowbrook Wildlife Center

If you come across a wild animal and are concerned, leave it alone. Call Willowbrook Wildlife Center for advice at (630) 942-6200. The center is located at 525 S. Park Blvd. in Glen Ellyn and is open 9 a.m. to 5 p.m. every day except select holidays. Recorded messages provide general information for callers when the center is closed.

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