Muskrat tales: How this swimming rodent differs from a beaver

This time of year, I often see a muskrat gracefully swimming along the surface of our pond with a mouth full of greens. At a certain location, the animal dives down and enters its bank den with a curbside, I mean, pondside delivery. One has to wonder; how did such an agile swimmer get stuck with the name “muskrat?”

In some parts of the world, there are musk deer, in other areas, musk oxen, in the Midwest, we have muskrats. All of these animals possess musk, a greasy secretion with a powerful odor produced in a glandular sac. On muskrats, a pair of these glands are located on the lower abdomen.

Like a mouse, squirrel or its larger aquatic accomplice the beaver, the muskrat is a rodent. Both beavers and muskrats have two pairs of gnawing teeth, one pair on each jaw, which grows continuously. Constant gnawing keeps the edge of these teeth sharp like a chisel. Like the beaver, the muskrat is chiefly a vegetarian.

Unlike the beaver which chews on woody plants, the muskrat prefers the stems and roots of aquatic vegetation like cattails. You might be wondering, how do you chew an underwater root? The muskrat's teeth project past its lips so it can gnaw and swallow underwater without choking. In addition, the muskrat's ears and nose have special flaps that seal out water when it dives.

The muskrat, to keep itself from getting cold or wet, has a two-layer coating of fur consisting of a dense undercoat and coarse guard hairs. Although muskrats and humans are both warm-blooded, we are not created equal. A muskrat can increase its body temperature, by over 2 degrees Fahrenheit, before diving into icy water. Its bare tail can be used to help regulate the animal's temperature.

Besides acting as a radiator, the vertically-flattened tail serves both as a rudder and, when moved from side to side, like a propeller. Speaking of propulsion, the muskrat's large hind feet are webbed, which facilitates powerful swimming. A muskrat can move through water at a rate of one to three miles per hour. If swimming at the water's surface, you'll note that the eyes and ears are located near the top of the head so that the muskrat can stay mostly submerged.

In areas with shallow waters, like a cattail marsh, the muskrat builds a 3- to 4-foot-high dome-shaped lodge or house. The house is made of roots and stems of aquatic plants with a mixture of mud. Once the muskrat builder has piled an appropriate mound of vegetation, he hollows out an oval chamber in the interior, well above the water level, to which one or more underwater tunnels gain entrance. The walls of the house can be a foot thick, protect the muskrats inside from predators and act as insulation, keeping the inside warm in winter and cool in summer.

Here along Stillman Nature Center's pond, where cattails are sparse, the muskrat digs a bank den for its home. Their breeding season runs from March through August. Does my aquatic neighbor have young? I would imagine so. Although a muskrat usually will not eat its food where it grows. Instead, the animal takes the food to a location where it is safe from predators. Nowadays, that strategy sounds familiar to this human.

Mark Spreyer is executive director of the Stillman Nature Center in Barrington. Email him at stillnc@wildblue.net.