Beavers are present in Illinois, having made a significant return to the state’s waterways. These industrious rodents, once nearly eliminated from the region, now thrive across various aquatic environments. Their successful comeback contributes to Illinois’ rich biodiversity. Understanding their habits and interaction with human environments is important for coexistence.
Beavers Across Illinois
Beavers faced a severe decline in Illinois by the mid-1800s due to extensive trapping, leading to their near elimination by the early 1900s. Reintroduction efforts from the late 1920s to early 1950s, along with recolonization from neighboring states, helped reestablish them. By the mid-1950s, beavers were reestablished in at least half of Illinois’ counties, and today, they are common throughout the entire state.
Beavers inhabit a variety of aquatic environments across Illinois, including streams, rivers, ponds, lakes, drainage ditches, canals, and backwater areas. While their distribution is widespread, their abundance can vary by watershed. The state’s beaver population is stable, a testament to their adaptability.
Illinois Beaver Characteristics and Habits
Illinois beavers are the largest rodents in the state, typically weighing between 25 to 60 pounds and measuring 3 to 3½ feet in length, including their tail. Their bodies are covered with dense, reddish-brown to blackish fur, which is waterproof, and they possess broad, flat, scaly tails. Their hind feet are webbed, aiding aquatic movements, while their front paws are hand-like, allowing skillful manipulation of materials. Beavers have large, orange incisors that grow continuously, requiring constant gnawing on wood to keep them worn down.
These animals are herbivores, primarily consuming tree bark, leaves, twigs, and aquatic plants. Their diet includes species like aspen, birch, cottonwood, willow, maple, grasses, sedges, water lilies, and cattails. Beavers are well-known for their dam and lodge building, a behavior driven by the need for protection from predators and to create deep-water habitats. Dams raise water levels, providing underwater entrances to their lodges, which are dome-shaped structures of sticks and mud, or burrows dug into banks. This construction also allows them to store food underwater for winter.
Coexisting with Beavers
Beavers are often called “ecosystem engineers” due to their significant impact on the environment. Their dam-building activities create wetlands, which enhance biodiversity by providing habitat for various species, including fish, waterfowl, amphibians, and insects. Beaver dams also improve water quality by reducing soil erosion, retaining sediment, and filtering pollutants, while storing water to mitigate drought conditions and manage floods.
Despite their ecological contributions, beavers can cause nuisances for humans through tree cutting, damming drainage systems, and localized flooding. Residents can protect individual trees by wrapping their trunks with wire mesh or hardware cloth to a height of about three feet. To manage water levels caused by beaver dams, devices such as Clemson pond levelers, also known as beaver tubes, can be installed. These systems allow water to flow through the dam without stimulating beavers to rebuild.
Physical removal of dams is not recommended as beavers will quickly rebuild, often in the same or nearby locations. When beaver activity causes significant property damage, the Illinois Department of Natural Resources (IDNR) can provide technical assistance and information on management options. In some cases, a nuisance animal removal permit may be issued by an IDNR district wildlife biologist. Licensed nuisance wildlife control operators can also be hired for humane removal or deterrence strategies. Shooting beavers is prohibited by state law unless specifically authorized by a permit.