Muskrats (Ondatra zibethicus) are medium-sized, semi-aquatic rodents common throughout North America, inhabiting wetlands, marshes, and slow-moving waterways. They are distinct from beavers due to their smaller size, laterally flattened tail, and dome-shaped lodges constructed from vegetation and mud. The muskrat’s ecological niche is defined by its strong dependency on these aquatic environments, where it spends most of its time swimming and foraging. This lifestyle naturally shapes the animal’s diet, which is largely determined by the readily available resources in its habitat. A common question arises regarding whether this rodent includes fish in its regular food intake.
The Role of Fish in the Muskrat Diet
Muskrats are generally classified as opportunistic omnivores, though their diet is overwhelmingly plant-based. Studies estimate that aquatic vegetation constitutes about 95% of a muskrat’s total food intake, leaving only a small percentage for other items. While they do consume animal matter, fish are not a primary or regularly hunted food source for these animals.
When muskrats do consume fish, it is typically an opportunistic event involving slow-moving, sick, or already dead individuals. They lack the specialized anatomy or hunting speed required to capture healthy, fast-swimming fish consistently. Other small aquatic organisms, such as freshwater mussels, crayfish, snails, and frogs, are more commonly consumed as supplementary animal protein. This carnivorous component of the diet often increases during periods of plant scarcity, such as in winter or following an “eat-out” event where local vegetation has been depleted.
Predominant Food Sources: Aquatic Vegetation
The foundational diet of the muskrat consists almost entirely of plant matter harvested from its watery environment. They rely on a wide array of aquatic vegetation, with certain species forming the core of their nutrition. The roots, stems, leaves, and tubers of these plants provide the necessary high-fiber content for their survival.
Cattails (Typha species) are the most important food source for muskrats across their range. They utilize almost all parts of the plant, but often show a preference for the core of the cattail stem, which is easier to digest. Other staple plants include sedges, bulrushes, water lilies, and pond weeds, which are eaten both above and below the water surface.
This dependence on vegetation dictates the muskrat’s habitat selection, as they must settle in areas with an abundant supply. Seasonal changes influence what parts of the plants they consume; for example, they rely heavily on roots and tubers during the colder months when above-ground growth is limited. The muskrat plays a significant role in shaping the plant composition of the wetlands it inhabits.
Foraging Behavior and Environmental Adaptations
The muskrat’s feeding behavior is intrinsically linked to its semi-aquatic adaptations and a need for predator avoidance. As they forage, they cut vegetation using their large front incisors. They are able to do this underwater because their lips close behind their teeth, preventing water from entering their mouth.
Once plant material is harvested, the muskrat typically carries it to a secure location for consumption. They often construct small, temporary mounds of mud and vegetation known as “feeding platforms,” “feeding huts,” or “push-ups” where they can eat while protected from predators. These feeding stations are usually situated within 15 to 150 meters of their main lodge or burrow.
Muskrats utilize several physical adaptations for foraging and movement. Their small, agile forefeet are well-suited for manipulating the plant materials they gather, while their partially webbed hind feet and vertically flattened tail provide efficient propulsion through the water. In preparation for winter, muskrats may also create food caches, storing roots and tubers near their dens for access when the water surface is frozen.