Close to 1,500 Illinois records put the American beaver along nearly every kind of water the state offers. Cook County leads with 545, followed by Lake and DuPage in the northeast, while Cache River State Natural Area and the country around Crab Orchard National Wildlife Refuge carry the record into the swamp and bottomland country of the far south.
Slow water and a supply of wood
A beaver needs standing or slow-moving water ringed with the trees and shrubs it cuts for food and building material, and Illinois provides that combination from the lake country at Chain O’ Lakes State Park to the wooded sloughs of the Cache River wetlands. At Emiquon and other Illinois River backwaters, quiet side channels and wooded banks fit the same pattern. By damming small streams and digging canals, the beaver creates ponded wetlands that hold water through dry spells and shelter frogs, turtles, and waterfowl.
Busy in every season
Reports arrive in all twelve months, with the strongest stretch from March through May. That spring rise lines up with the season when two-year-olds leave their parents’ lodge and travel the waterways looking for an unclaimed stretch of stream, which puts more beavers on the move and in view. Even in midwinter the animal stays active beneath the ice, living off a pile of branches stored near the lodge.
Status in Illinois
NatureServe ranks the American beaver S5, Secure, in Illinois, and the species is native to the state. USGS NAS does not list it as nonindigenous here.
Full species profile
