Muskrat

Physical Description and Adaptations

The muskrat is a robust, medium-sized rodent, typically measuring between 40 and 70 centimetres in total length with its distinctive tail accounting for about half that measurement. Adults weigh between 0.6 and 2 kilograms, making them roughly four times heavier than a common brown rat but significantly smaller than the beavers with which they often share habitats. Their body is covered in a double layer of short, thick fur that ranges from medium to dark brown or black, with a lighter-coloured belly providing countershading. This dense, waterproof fur is crucial for insulation in cold aquatic environments. As muskrats age, their fur often develops patches of gray. The fur has historically been a valuable commodity, becoming prime for trapping in northern regions at the beginning of December.

The animal's most recognizable features are its adaptations for a semiaquatic life. Its hind feet are partially webbed, serving as the primary means of propulsion through the water. The long tail, which is vertically flattened and covered in scales rather than hair, functions as a rudder for steering and provides directional stability. Muskrats can swim underwater for impressive durations of 12 to 17 minutes due to physiological adaptations that make them less sensitive to carbon dioxide buildup, similar to seals and whales. They can also close their ears to prevent water entry. On land, their dragging tail leaves a characteristic track. Musk glands are situated in the tail and are used for scent marking territory.

Habitat and Distribution

Muskrats are intrinsically linked to wetland environments, inhabiting marshes, swamps, ponds, lakes, and slow-moving streams across North America. Their native range spans most of Canada and the United States, extending into a small portion of northern Mexico. They are notably absent from Florida, where the round-tailed muskrat occupies a similar ecological niche, a situation potentially influenced by alligator predation. Muskrats demonstrate considerable adaptability, even living in waterways affected by sulfurous runoff from coal mines where fish and frogs cannot survive.

While human activity has destroyed many natural wetlands, muskrats have also colonized new habitats created by irrigation channels and canals. Their populations naturally undergo cyclical booms and declines over six- to ten-year periods, a pattern shared with close relatives like lemmings. However, concerning trends have emerged, with a reported decline of at least half in 34 U.S. states beginning in the 1990s and early 2000s. In some states the collapse was near total, ranging from 90 to 99 percent. Similarly, in Canada's Northwest Territories, the species was listed as at risk in 2026 due to observed declines noted by local knowledge holders, despite the animal still being widespread across the territory.

Behaviour and Life Cycle

Muskrats are largely nocturnal or crepuscular, being most active near dawn and dusk. They live in monogamous family units consisting of a breeding pair and their offspring. During the spring, violent territorial disputes between muskrats over mates and territory are common and often result in injury or death. To shelter their families, they construct elaborate dwellings. In banks along water bodies, they dig burrows with underwater entrances that are 15 to 20 centimetres wide. In marshy areas without stable banks, they build dome-shaped lodges called push-ups from vegetation and mud, which can be up to 90 centimetres tall.

In snowy areas, they keep the openings to these push-ups closed by plugging them with vegetation, which they replace daily. Some lodges are swept away in spring floods and must be rebuilt each year. They also build feeding platforms in the water from cut vegetation. These rodents are prolific breeders. The mating season runs from late March through July, often occurring underwater. A female can produce two to three litters per year between March and October, each containing six to eight young on average, though litters of up to 15 have been noted in warmer months. The blind and hairless pups, weighing only about 22 grams at birth, are weaned after about eight weeks. Young muskrats in southern regions mature in approximately six months, while those in colder northern climates take about a year to reach maturity.

Diet and Ecological Role

Muskrats are primarily herbivorous, with plant material composing about 95 percent of their diet. They favour vegetation such as cattails, yellow water lilies, and other aquatic plants. They do not store food for winter but may consume the inner vegetation of their lodges. The remaining portion of their diet consists of small animals including freshwater mussels, crayfish, frogs, fish, and small turtles. They create and maintain trails through swamps and continue to use them under the ice in winter. While they may appear to steal food from beaver caches, observations have also noted seemingly cooperative relationships between the two species.

Their feeding and construction activities have a profound impact on wetland ecology. By grazing on plants, they help maintain open water areas, which in turn provides crucial habitat for aquatic birds and other wildlife. Their selective removal of preferred plant species can alter the composition of wetland vegetation, and they are thought to play a major role in determining the vegetation of prairie wetlands. The surfaces of their lodges offer shelter and resting spots for creatures like turtles, snakes, and insects. Furthermore, muskrats form a vital link in the food chain, serving as prey for a wide array of predators including mink, foxes, coyotes, wolves, bears, lynxes, raptors, snapping turtles, and alligators. In winter, large ungulates like moose and elk may feed on the vegetation of muskrat push-ups when other food is scarce.

Introduction and Status as an Invasive Species

In the early 20th century, muskrats were introduced to Europe and parts of Asia primarily for fur farming. For instance, in 1905, two males and three females were released into a park in Dobříš, in what is now the Czech Republic. They have since spread widely and are now considered a problematic invasive species across much of northwestern Europe. Since August 2, 2017, the muskrat has been listed as an invasive alien species of Union concern by the European Union, prohibiting its import, breeding, transport, sale, or intentional release anywhere in the EU.

In low-lying countries like Belgium, the Netherlands, and France, the muskrat's extensive burrowing activity poses a serious threat to the structural integrity of dikes and levees, which are essential for flood control. Their feeding can also damage agricultural crops like corn grown near water. Consequently, these nations employ trapping, hunting, and poisoning programs in an attempt to control their populations. In the former Soviet Union, the golden jackal became a significant predator of introduced muskrats. During one winter in Central Asia, muskrats made up 12.3 percent of jackal feces contents, and jackals destroyed 71 percent of muskrat houses. The species is also classified as a prohibited new organism under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing its importation.

Human Uses and Cultural Significance

For centuries, muskrats have been an important resource for humans in North America. Their dense, warm fur was a staple of the continental fur trade in the 20th century. The fur was often specially trimmed and dyed to be sold widely in the United States as Hudson seal fur. Notably, the winter hats of the Royal Canadian Mounted Police are traditionally made from muskrat fur. As a food source, muskrats have been consumed by various Indigenous cultures and other communities. Preparation requires careful removal of the musk glands from the tail to prevent the meat from being tainted.

A unique tradition persists among some Catholic communities in southeastern Michigan, where a longstanding dispensation allows the consumption of muskrat on days when meat is otherwise prohibited, such as Lenten Fridays and Ash Wednesday. In 2019, it was reported that Lenten muskrat dinners along the Detroit River could consume up to 900 animals at a single event. In Indigenous cultures, the muskrat holds a place of honour. Some nations use observations of muskrat lodge size and construction timing to predict winter snowfall levels. In the creation myths of several peoples, including the Haudenosaunee, the muskrat is the heroic animal that dives to the bottom of the primordial waters to retrieve the mud from which the earth is formed, after other animals have failed.

Conservation and Population Trends

While muskrats remain widespread, significant population declines have been documented in recent decades across large portions of their native range. In the United States, a collapse began in the 1990s and early 2000s, with populations falling by at least half in 34 states and by 90 to 99 percent in some areas. By 2024, Rhode Island's muskrat population was estimated at only about 15 percent of its former size several decades prior. The exact causes of this widespread decline are not fully understood but are linked to habitat loss, pollution, disease, changing wetland conditions, and possibly increased predation.

In Canada, similar concerns are noted. As of 2026, the common muskrat is considered a species at risk in the Northwest Territories, where local observers have reported noticeable decreases in numbers. These trends highlight the muskrat's role as an indicator species for wetland health. Their decline signals potential broader ecological issues within the aquatic habitats they inhabit, underscoring the importance of ongoing monitoring and wetland conservation efforts. The animal can also be infected by parasites like the trematode Metorchis conjunctus, which may be a factor in population health.

Taxonomy and Etymology

The muskrat, Ondatra zibethicus, is the only living species in its genus. It is the largest member of the subfamily Arvicolinae, which includes 142 other species of rodents such as voles and lemmings. Its closest living relative is the round-tailed muskrat (Neofiber alleni) found in Florida. Scientists recognize 16 different subspecies of muskrat, including O. z. osoyoosensis and O. z. zibethicus, which are distributed across the continent.

The animal's scientific and common names have distinct origins. The genus name Ondatra comes from the Huron word for the animal, ondathra, which entered scientific language via French. The species name zibethicus is Latin and means musky, derived from zibethus referring to civet musk. The common name muskrat likely evolved from Algonquian words such as muscascus, which means it is red and refers to the animal's colouring, or from the Abenaki word mòskwas. The association with its musky scent and its rat-like tail later solidified the name muskrat, though it was also historically called the musk-beaver.

Questions about Muskrat

Are muskrats rats?

No, muskrats are not true rats. Despite the name, they are actually large voles and are members of the subfamily Arvicolinae, which includes lemmings and other voles. Their closest relative is the round-tailed muskrat of Florida. The common name likely originated from Algonquian or Abenaki words and was later altered due to the animal's musky odour and its rat-like tail. They are more closely related to mice and hamsters than to rats.

What do muskrats eat?

Muskrats are primarily vegetarians, with plants making up about 95 percent of their diet. They commonly eat cattails, water lilies, and other aquatic vegetation. They also consume small amounts of animal matter, including freshwater mussels, crayfish, frogs, fish, and small turtles. They do not store food for the winter but may eat the inner vegetation of their own lodges. They create feeding platforms in the water from cut pieces of plants.

Where do muskrats live?

Muskrats inhabit a variety of wetland environments including marshes, swamps, ponds, lakes, and slow-moving streams. They are native to most of Canada, the United States, and northern Mexico. They require water bodies with abundant vegetation. They build homes either by burrowing into banks with an underwater entrance or, in marshy areas, by constructing dome-shaped lodges called push-ups from plants and mud. They can also live in human-made canals and irrigation channels.

Are muskrat populations declining?

Yes, significant muskrat population declines have been reported across much of their native North American range. In the United States, declines began in the 1990s, with populations reduced by at least half in 34 states and by over 90 percent in some. In Canada, the species is listed as at risk in the Northwest Territories as of 2026 due to observed declines by local knowledge holders. The causes involve habitat loss, pollution, disease, and ecological changes in wetlands, making the muskrat an indicator of wetland health.

Why are muskrats considered invasive in Europe?

Muskrats were introduced to Europe in the early 20th century for fur farming. They are considered invasive because their burrowing damages dikes, levees, and river banks, threatening flood control. They also outcompete native species and damage crops. The European Union listed them as an invasive alien species of concern on August 2, 2017.

Sources: Wikipedia and current public reporting, checked by the Your Space Hamilton desk. Last updated 2026-10-22.