It was the calm before the storm. The pond was the calm, sheer and smooth. The bus that was due with over 100 middle school students for a field trip was the impending storm. Although students are always a good storm, filling the forest preserve with energy, it is inside these few moments of quiet before the bus arrives that nature seems to poke its head out to see if the coast is clear. This particular morning, the glassy water became rippled in V-shapes like geese migrating in the sky. A lone muskrat (Ondatra zibethicus) slid through the water towards a clump of cattail, its snake-like tail slithering behind him.
The muskrat gets the first part of its name from the strong-smelling yellow substance it excretes. This musk smells for days after secretion. Most likely a form of communication, the muskrat has been known to slather this secretion all over its home range. The second part of this critter’s name because it had an adaptable lifestyle and omnivorous diet; it is not a true rat of the genus Rattus. This football-sized rodent sports an 8-inch long scaly tail and weighs about three pounds.
June is the height of breeding season for muskrats. Young from a female’s first (of up to three) litters can already be seen nibbling on cattail and bulrush during daylight hours. Although considered primarily herbivorous, muskrats have been known to feed on crayfish and freshwater clams in times when vegetation is scarce. Surprisingly, they have also been documented eating their own young when food is in short supply!
Muskrats are talented architects that are able to build lodges of vegetation and mud up to six feet high and eight feet in diameter. The lodges are built near the bank and can be used for many years. These abodes have a central chamber inside that sits a few inches above the water level. Depending on the size of the lodge, there may be interconnected chambers as well, built on varying levels. Regardless of how many rooms a muskrat family has added, there are always multiple underwater entrances.
Lodges aren’t the only dwelling muskrats create. Bank dens are commonly used in moving waterways. This type of den consists of a series of tunnels, chambers, and ventilation holes carved into the clay and mud at the edges of a river or stream. These tunnels can reach lengths of up to 200 yards long, and the chambers are a cool relief from the scorching temperatures of summer days. Entrances to bank dens are also built below the water’s surface. Although when water levels are especially low, the muskrats’ front door can become exposed.
Look for these homes as signs of muskrat activity in any Lake County Forest Preserve with a wetland. Spend a morning with the family on Saturday, July 7, for a Walk with a Naturalist. This time and site will offer a good chance to spy on these mammals in action. Or find your own moment of calm in nature, and see who peeks out at you.