The muskrat, Ondatra zibethicus, is a semi-aquatic rodent that spends much of its life in wetlands across North America. It lives around marshes, ponds, lakes, rivers, streams, drainage channels, and other areas with shallow water and dense vegetation. Despite its name, the muskrat is not a true rat. It belongs to the family Cricetidae, the same family that contains voles, lemmings, hamsters, and several groups of New World rodents.
A muskrat has a compact body, short legs, small ears, dense brown fur, and a long tail covered with scales. The tail is flattened from side to side, which gives it a very different shape from the round tail of a true rat.
Adult muskrats measure about 41 to 62 centimeters from the nose to the end of the tail. Their weight ranges from about 680 to 1,800 grams, although body mass changes with age, sex, season, and location.
The animal is strongly connected to water. It can swim underwater, enter a burrow through a submerged entrance, and remain below the surface for about 15 to 20 minutes.
Its diet consists mainly of aquatic plants. Cattails, bulrushes, sedges, water lilies, arrowhead, pondweed, wild rice, and other wetland plants provide much of its food.
Muskrats also eat animal matter. Fish, frogs, crayfish, mussels, snails, and carrion have all been recorded in their diet. A 2022 study documented a muskrat repeatedly catching crayfish and carrying them back to its den.
The animal also changes the wetland where it lives. By eating vegetation, digging burrows, building lodges, and creating feeding platforms, it changes the structure of marshes and provides shelter that other animals use.
Its life is short compared with the lifespan of many larger mammals. Wild muskrats can live for about 4 years, while the species reproduces rapidly and can produce several litters in a year in southern parts of its range.
During winter, a muskrat does not migrate hundreds of kilometers to escape cold weather. It stays within its wetland system and moves through water, channels, burrows, and vegetation to find food and shelter.
It is a small animal with a large effect on the wetland around it.
What does a muskrat look like?
The muskrat has a stocky body covered with dense fur. The upperparts are normally brown, while the underside is lighter.
Adults measure about 41 to 62 cm in total length and weigh about 680 to 1,800 g.
The head is large compared with the body, and the ears are small enough to disappear within the fur. Long whiskers surround the nose and help the animal detect objects at close range.
The hind feet are larger than the front feet and have partial webbing. This helps the muskrat push against the water while swimming.
The tail is one of its clearest identifying features. It is long, narrow, nearly hairless, scaly, and flattened from side to side.
The dense underfur also has an important function. It traps air close to the skin and provides insulation while the animal swims in cold water.
Where do muskrats live?
Muskrats are native to North America. Their range extends from northern Alaska and Canada south through much of the United States and into parts of northern Mexico.
They occur in marshes, ponds, lakes, rivers, streams, oxbow lakes, drainage channels, dikes, and other wetlands.
The species is strongly associated with emergent plants such as cattails, bulrushes, sedges, reeds, cordgrass, and rushes. These plants provide both food and building material.
USDA Forest Service research describes water depths of about 46 centimeters to 1.2 meters as suitable in some lake and pond habitats. Coastal populations use shallower water, with recommended depths varying by habitat.
Muskrats also use wetlands where water remains open during winter. Deep enough water prevents the entire habitat from freezing and gives the animals access to underwater food.
They can live in both freshwater and brackish coastal marshes. Their exact habitat depends on water level, vegetation density, food availability, and bank structure.
How big is a muskrat?
Adult muskrats measure about 41 to 62 cm long.
Their mass ranges from approximately 680 to 1,800 g. A typical adult therefore weighs less than 2 kg.
Some National Park Service information describes muskrats as weighing about 2 to 4 pounds, which equals roughly 0.9 to 1.8 kg.
The animal looks larger than its actual mass because its fur is dense and thick.
Its short legs are hidden beneath the body when it swims, giving the animal a streamlined appearance in the water.
How does a muskrat breathe underwater?
A muskrat does not breathe underwater. It is a mammal, so it breathes air with its lungs.
Instead, it holds its breath while diving. National Park Service information records dives lasting up to about 20 minutes, while Animal Diversity Web information places the recorded diving period at about 15 minutes.
The exact diving time changes with the animal's activity and the situation. A muskrat escaping a predator has a different oxygen demand from one resting inside underwater vegetation.
The animal's body is adapted for repeated diving. Its eyes and nostrils remain functional around water, while dense fur reduces heat loss during swimming.
The underwater entrance of a lodge or burrow gives the muskrat direct access to air without requiring it to cross exposed ground.
What does a muskrat eat?
Muskrats are mainly herbivores. Their diet consists largely of aquatic plants and the parts of plants that grow above or below the water.
Cattails, bulrushes, sedges, arrowhead, water lilies, wild rice, pondweed, pickerelweed, spikerush, smartweed, and other plants appear in their diet.
The animal eats roots, rhizomes, stems, leaves, and other soft plant material.
Muskrats also eat crops when wetlands are close to agricultural land. Acorns and maple seeds have also been recorded as food.
Animal food forms a smaller part of the diet. Fish, frogs, crustaceans, mussels, snails, insects, and dead birds have all been recorded.
A 2022 study from Mississippi documented a common muskrat repeatedly catching crayfish and carrying them to its den. The observation was important because muskrats are often described mainly as plant eaters.
How much food does a muskrat eat each day?
Animal Diversity Web reports that a muskrat can consume about one-third of its body weight in food per day.
For an animal weighing 1,136 g, one-third equals about 379 g of food in 24 hours.
This food does not consist entirely of meat. Aquatic vegetation supplies most of the daily intake.
The amount changes with body size, season, temperature, food quality, and reproductive condition.
A lactating female has higher nutritional demands than a resting adult, while a growing juvenile also requires energy for rapid development.
Does a muskrat store food for winter?
A muskrat does not store large winter food caches in the same way as a beaver.
Instead, it continues searching for fresh food. During winter, it can travel beneath ice and reach aquatic plants growing below the frozen surface.
National Park Service information specifically notes that muskrats need to eat fresh plants each day rather than depending on a large stored food supply.
Muskrats also carry vegetation to feeding platforms and sheltered areas. This is different from creating a large food cache intended to last through an entire winter.
When water levels fall, a muskrat can dig channels between its lodge or burrow and deeper water, giving it access to food and an underwater travel route.
How do muskrats build their homes?
Muskrats use two main types of shelters: bank burrows and lodges built from wetland vegetation.
A bank burrow begins in the side of a pond, stream, or marsh bank. Some burrows reach about 15 meters in length.
The entrance is normally underwater. Inside, the burrow contains chambers where the animals rest and raise their young.
In marshes without suitable banks, muskrats construct dome-shaped lodges from cattails, bulrushes, reeds, and other plants.
The lodge can rise above the water while the entrance remains below the surface.
Muskrats also construct feeding platforms. These small structures allow them to sit above the water while eating plant material.
During periods of low water, the animals can dig channels from their shelters toward deeper water.
How does a muskrat swim?
The muskrat's body is well suited to swimming. Its hind feet have partial webbing, its fur provides insulation, and its flattened tail assists with steering.
National Park Service information reports swimming speeds of about 3 miles per hour, equivalent to roughly 4.8 kilometers per hour.
The animal can dive rapidly when threatened. It can also swim beneath ice to reach food or move between shelters.
On land, its short legs are less efficient than its swimming adaptations. Water is the main escape route when a predator approaches.
Does a muskrat migrate?
Muskrats do not perform long-distance seasonal migrations like many birds or caribou.
They normally remain within the same wetland system throughout the year.
USDA Forest Service information reports that muskrats normally remain within about 15 meters of their lodges while foraging, although individuals can travel as far as about 183 meters from the lodge.
Young animals can move away from their birthplace after becoming independent. Adults also relocate when food, water levels, or habitat conditions change.
A muskrat can therefore move through connected ponds, streams, marshes, and drainage channels without making a true seasonal migration.
What sounds do muskrats make?
Muskrats communicate with sounds as well as scent.
Recorded sounds include squeaks, squeals, chatters, and short calls. Young muskrats produce high-pitched sounds during interactions with their mother.
Adult muskrats also produce sounds during social interactions and aggressive encounters.
Scent communication is another part of their behavior. Muskrats have scent glands near the base of the tail that produce a strong musky odor.
The odor explains the name “muskrat.” It does not come from the animal being closely related to rats.
Is a muskrat friendly or tame?
A wild muskrat is not a domesticated animal. It normally avoids people and attempts to escape when approached.
A muskrat that is trapped, cornered, or handled can bite in self-defense. Its incisors are strong enough to cut through tough vegetation.
Most encounters end with the animal entering water, diving below the surface, or disappearing into vegetation.
Muskrats should therefore be observed from a distance rather than handled like a pet.
They are not normally aggressive toward people. Their normal response to a person is avoidance.
Which animals prey on muskrats?
Muskrats are prey for a large group of wetland predators.
American mink, raccoons, bobcats, coyotes, red foxes, domestic cats, dogs, barn owls, barred owls, great horned owls, northern harriers, bald eagles, cottonmouths, alligators, snapping turtles, bullfrogs, gar, bowfin, and largemouth bass have all been recorded as predators.
American mink are particularly well suited to hunting muskrats because they can enter water and investigate submerged burrows.
Young muskrats face greater danger because they are small and spend time close to their nesting chamber.
The underwater entrances of burrows and lodges provide an important escape route. A muskrat can dive and reach its shelter before a predator catches it.
How do muskrats reproduce?
Muskrats can breed from March through October in northern populations, with breeding activity concentrated from March through June.
Southern populations have a longer breeding season and can produce more litters each year.
Gestation lasts about 28 to 30 days.
In areas north of about 37 degrees north latitude, litters contain roughly 4 to 7 young, with up to 3 litters per year reported in the USDA Forest Service review.
South of 37 degrees north latitude, litters average about 3 to 4 young, while 3 or more litters per year are reported.
Newborn muskrats are small and helpless at birth. Their eyes are closed and they remain dependent on the mother during their early development.
Weaning occurs at about 4 weeks.
Sexual maturity varies between populations. USDA Forest Service information gives maturity from about 6 to 8 weeks in some populations and about 1 year in others.
How long do muskrats live?
Muskrats have a relatively short lifespan in the wild.
The USDA Forest Service review gives a wild lifespan of up to about 4 years.
High mortality is linked to predators, disease, harsh weather, habitat changes, and competition.
Rapid reproduction helps populations recover after periods of high mortality.
Muskrat populations also show cycles in some regions. USDA Forest Service research describes population cycles lasting roughly 6 to 14 years.
How do muskrats affect wetlands?
Muskrats can change wetlands through feeding, burrowing, and construction.
They eat large quantities of aquatic vegetation, which can create openings in dense stands of plants.
These openings can maintain areas of open water inside marshes. Other wetland animals can use the spaces for movement and feeding.
Muskrat lodges also provide shelter for other species. Snakes, turtles, toads, Canada geese, and black terns have all been recorded using muskrat lodges.
Their influence can become negative when population numbers become very high. In some coastal marshes, population peaks produce areas called “eat-outs,” where muskrats remove large quantities of preferred vegetation.
USDA Forest Service research reports that preferred bulrush must regenerate within about 5 months after an eat-out in order to avoid dying out.
Muskrat burrowing can also damage human structures. Burrows in dikes, levees, pond banks, and similar structures can weaken soil and increase erosion.
At the same time, muskrats are part of the wetland food web. Their bodies transfer energy from plants to predators such as mink, foxes, owls, eagles, turtles, snakes, and large fish.
What happens to muskrat populations when wetlands change?
Muskrats depend on a balance between water and vegetation.
USDA Forest Service habitat research describes high-quality habitat as having dense emergent vegetation surrounded by terrestrial herbaceous vegetation. In some models, at least 50 percent dense emergent vegetation produced suitable conditions.
Water levels that fall too far can reduce food availability and expose shelters. Prolonged flooding can also destroy food plants.
Very dense vegetation is not ideal either. When a wetland becomes completely choked with plants, muskrat numbers can decline.
Some management programs use controlled burning to remove old vegetation and encourage new growth. The effect depends on season, water level, plant species, and local conditions.
Dredging, diking, urban development, mosquito-control projects, and wetland drainage can also reduce suitable habitat.
Is the muskrat endangered?
The muskrat has a broad distribution across North America and remains common in suitable wetland habitat.
The species is not federally protected in the United States according to the USDA Forest Service review.
Local populations can still decline when wetlands are drained, water levels change sharply, or aquatic vegetation disappears.
The species therefore has a very different conservation situation from a rare wetland mammal. Its broad range and rapid reproduction support stable populations in suitable habitats, while local habitat destruction can still remove entire colonies.
Sources:
- USDA Forest Service – Common Muskrat, Ondatra zibethicus
- National Park Service – Muskrat
- National Park Service – Muskrat at Minute Man National Historical Park
- USDA Forest Service – Direct Observation of Muskrat Feeding on Crayfish
- Animal Diversity Web – Muskrat
- Indiana Department of Natural Resources – Muskrat
- Texas Tech University – Common Muskrat
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