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Living With
Beavers in Dupage County
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 Living with Beavers
History
Although once extinct in DuPage County, beavers are again making their homes in many of our rivers, streams and lakes.
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 post in the early 1800s called Fort Dearborn, and DuPage County owes its name and the name of its main river to French fur trader DuPhaze.
So popular were the beavers' flesh, fur and leathery tail that the animals' numbers steadily dwindled from the 1850s until the turn of the century. It became extinct in Illinois in the early 1900s. From 1929 to 1936, attempts were made to reintroduce the beaver in Illinois. By 1954, beavers had dispersed to almost half the counties in the state.
Habits and Habitat
Dam building is an important element in the beaver's survival. Dams are constructed of branches of cottonwoods, willows and other trees cut by the beaver and stabilized with rocks and mud. A damned stream becomes a pond providing water for drinking, a travel route and a home site.
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. Usually, there are four beaver in the spring-born litters. At two years of age, the beaver offspring leave the colony and seek their own home site, thereby spreading the beaver population along waterways and re-colonizing vacant habitat.
Colony members usually construct a lodge, a dome-shaped home of branches and mud in the water. The lodge is warm and dry inside, sometimes rising five feet above the water, and is accessible through underwater passages. Beavers may also dig a tunnel and den in a riverbank or lake shore. The only evidence of a bank den may be the submerged entrance.
Most active after sundown, beavers are strict vegetarians and will eat tender twigs, 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 40-60 pounds, the beaver is one of the largest aquatic rodents. A full-grown beaver is about four feet long, including the one-foot tail. Its body is stocky with short legs, sharp front claws and webbed feet. Its glossy coat is tan to dark brown, with coarse over-hair, and a fine, dense under-fur. The beaver's trademark is its large front teeth. Two lower and two ever-growing upper incisors are essential tools for its lumberjack activities.
People Often confuse a beaver in the wild with its smaller "cousin," the muskrat. The most distinctive feature of the beaver is the large, scaly and paddle-like tail. The tail is used as a rudder while swimming. When slapped against the water, the tail serves as a warning signal to other beavers.
Telltale signs of a beaver's presence are a dam, conical-shaped tree stumps and diagonally cut branches. The marks made by the beaver's sharp, front teeth can be seen as smooth cuts in the wood. Once a tree is cut down, beavers will eventually gnaw it into portable pieces, eat the bark from the trunk and branches, and move branches to the nearby waterway.
Recommended Deterrent Techniques
Light, inexpensive wire fencing (minimum of three feet high) is the simplest long-term solution for keeping beaver out of waterside property, or to protect clusters of trees. The lower three feet of individual trees can be wrapped with heavy gauge hardware cloth. Remember to loosen the wire as the tree grows.
Flooding due to beavers in DuPage County forest preserves is not controlled unless it causes 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 level.
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 in tearing down the dam than it is at rebuilding it.
- Do not use poisons. They are inhumane and may be illegal. They cal also result in secondary poisoning of raptors, wild scavengers and neighborhood pets.
- It is illegal to keep wild animals, even for a very 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 can not survive in their natural habitat.
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