The beaver may be three feet long and weigh up to 60 pounds. It has brown, waterproof hair and thick underfur on its body. The back feet are webbed for swimming. The nose and ears have valves that may be closed while swimming. Its nearly hairless tail is ﬂattened and paddlelike. There is a special membrane to protect the eyes while it swims. The lips can be closed behind the front teeth.
The beaver may be found statewide in Illinois. This animal was originally present in Illinois until the late 1800s, when it may have been extirpated due to excessive killing for beaver pelts. Beaver were stocked in the state and others moved in from adjacent states to restore populations. The beaver lives in streams, ponds, lakes, ditches, canals and backwaters. Trees should be present along these waterways for a beaver to reside there. The beaver eats the bark, twigs and leaves of trees and shrubs and also aquatic plants like duckweeds, some grasses and water lilies. This animal is nocturnal and has an aquatic lifestyle but will come to land to feed and raise its young or to move to a new water body. A beaver may slap its tail on the water’s surface to communicate with other beaver. It is also capable of making vocal sounds. Its incisors can be used to gnaw through trees. Trees are cut above the ground as the beaver sits upright. The branches and other tree parts are cut into small pieces and taken to the burrow or lodge. Burrows containing resting and nesting areas are dug into the bank, and the entrances placed below the water level. Generally, only one or two beaver occupy a bank burrow. The beaver will sometimes build a dome-shaped lodge of small trees, limbs and sticks. Several beaver may occupy a single lodge. The entrances to the lodge are below the water level, but the living area inside the lodge is above the water level. Mating occurs in January or February, and the young are born in May or June. Litter size is usually three or four. Young are covered with fur at birth.