Muskrat

Quick Take

• Muskrats play a starring role in some Native American creation myths, and the reason why might change how you see this overlooked rodent. Explore the mythology →
• When territory gets too crowded, muskrat family dynamics turn surprisingly ruthless, and the culprit is not who you would expect. See family dynamics →
• Muskrats can eat their own homes, and there is a very specific reason they would ever need to do so. Discover what muskrats eat →
• Despite being banned in some countries, this rodent also reportedly helps protect one of North America's most iconic animals from predators. See their protective role →

With its webbed feet and big rudder-like tail, the muskrat is a highly adaptable and successful species with a massive range across the freshwater wetlands and lakes of the Northern Hemisphere. Although it doesn’t engage in massive construction projects like the beaver, the muskrat does build sturdy homes around the water that can fit an entire family. These fast breeders sometimes come into conflict with each other over living space and resources.

5 Incredible Muskrat Facts

• The muskrat has traditionally been a source of food and fur for humans dating back thousands of years. By the early 20th century, it was one of the most valuable sources of fur in North America.
• Hundreds of muskrat fossils have been discovered dating back more than 4 million years. These fossils reveal that muskrat ancestors underwent an increase in body size, skull size, and tooth complexity over time.
• The muskrat is actually considered to be an invasive species in several non-native territories. Some countries have even banned it from being imported.
• As they age, these rodents show visible signs of wear such as graying fur.
• The muskrat has a prominent role in some Native American creation myths. According to these myths, the muskrat dug up the mud used to create the world.

Evolution And Origin

The history of the muskrat can sometimes be confusing because they are at times grouped together with the vole and still considered very close relatives. It is known that the muskrat is endemic to North America and descended from the Siberian vole that colonized the continent over 5 million years ago. There is only one species of muskrat, with 16 subspecies.

Classification and Scientific Name

The scientific name of the muskrat is Ondatra zibethicus. Ondatra comes from the Huron and Wyandot word for muskrat and comes from the French language, while zibethicus means ‘musky’ in Latin, being the adjective of zibethus meaning ‘civet musk; civet,’ due to its strong scent. The muskrat is the only currently living member of the genus Ondatra. More broadly, it belongs to the family Cricetidae in the larger order Rodentia along with the voles, lemmings, hamsters, and New World rats and mice. In fact, some taxonomists believe that the muskrat is really just a type of vole. Most voles are land-based, but there are several species of water voles (one of which lives in North America) that are semi-aquatic in nature.

Appearance

The animal’s body shape bears more than a passing resemblance to the beaver, but despite a shared habitat and lifestyle, the two animals are only distantly related within the order of Rodentia. The muskrat’s compact body measures around 10 to 14 inches long and weighs around 1.25 to 4.5 pounds. The flat, scaly tail adds another 8 to 11 inches to the total length. Its body is complemented by long whiskers, big teeth emerging from the skull, short legs, and webbed hind feet. The dense waterproof fur, which is dark brown in color (though lighter in the summer), can trap air underneath, which provides the muskrat with plenty of warmth and buoyancy. The lips can close behind the front incisors, allowing the muskrat to gnaw underwater without drowning. The small ears are barely visible through the fur.

Behavior

For most of the year, the muskrat is a solitary animal that may only share a den with others to conserve body heat. But during the breeding season, the muskrat’s social life centers on large family groups consisting of a male and female pair and all of their offspring. These groups squabble with each other for limited territory, which frequently leads to injury and death. If the territory becomes too crowded, then the female might actually kick out some of the offspring from the nest. These animals communicate with each other or warn off intruders by secreting a strong-smelling musk and by using a range of squeaks and squeals.

Although mostly nocturnal, muskrats are most active between the mid-afternoon and dusk periods. They are rather slow and cumbersome on land, but they are good swimmers that can stay underwater for 12 to 17 minutes at a time and even swim backward. These rodents paddle with their webbed hind feet and use their tail as a rudder.

The muskrat is also a good digger that can create tunnels from piles of vegetation and mud in or near shallow water. These homes, which are called push-ups, provide protection against predators and harsh elements. They usually have an underwater entrance and at least one chamber. They do not usually store food for the winter, but if resources start to dwindle, they can consume the walls of their own burrow. Sometimes the muskrat will resort to abandoned beaver dens as well. Some reports indicate that a muskrat may even cohabit with a beaver and help it identify nearby predators.

Habitat

The muskrat is endemic to the temperate and colder regions of the United States and Canada. The species was later introduced to Europe and Northern Asia (mostly Russia) in the early 20th century and spread quickly from there. The muskrat thrives in freshwater lakes, ponds, swamps, and marshes with 4 to 6 feet of water where it has plenty of room to build its nest.

Diet

Muskrats are actually omnivorous feeders that can opportunistically eat either vegetation or meat, but the vast bulk of their diet consists of plant matter, the most important of which is probably the cattail. The carnivorous part of the diet consists of small animals, including frogs, crayfish, turtles, mussels, and fish. The muskrat eats approximately one-third of its weight in food every single day.

Predators And Threats

The muskrat is an important source of food for a staggering number of predators such as coyotes, raccoons, barn owls, alligators, bobcats, cougars, foxes, bears, wolverines, eagles, cottonmouth water moccasins, minks, and river otters. In some areas, it serves as a critical link in the food chain between small prey and apex predators.

Muskrat hunting was more common in the past. It still occurs today, but not necessarily for resources. In some parts of Europe, the muskrat is considered to be an invasive species and therefore hunted and poisoned because of the damage it causes to dikes and levees on which people rely to prevent flooding. The species can also cause damage to crops and gardens near its natural habitat.

Because of their prolific reproductive rate, populations tend to survive well in most areas even when the muskrat is hunted or infected by disease (though Pennsylvania populations appear to be on a decades-long decline). And while large swaths of its native wetlands have been destroyed in the United States, the muskrat has adapted well to life near the newly created canals, irrigation channels, and small runoffs and streams. The decline of some natural predators has caused muskrat populations to swell beyond normal, sometimes even exceeding the ecosystem’s capacity to sustain them.

Reproduction And Life Cycle

The muskrat has a breeding season that occurs in the spring and summer between March and August. As mentioned before, the muskrat is a monogamous species that forms breeding pairs with a defined home range. However, if space is limited and populations are overcrowded, then the muskrat may form dominance hierarchies and engage in polygamous behavior, meaning that a single adult will have multiple partners throughout the breeding season. Mating occurs while the muskrats are partially submerged in the water or straddling some debris on the surface of the water.

The female typically produces one to three litters per year, each consisting of around five to eight young on average. After a gestation period of some 29 to 30 days, each kit is born small, hairless, and entirely reliant on the mother for protection and milk. For the first month of their lives, the young kits remain entirely dependent on her. The father plays almost no role in raising the young. It takes anywhere from six months to a year for the kits to fully develop, depending on the climate—northern muskrats are the slowest to grow.

The muskrat usually lives no more than three or four years in the wild but up to 10 years in captivity. Most are expected to die from predation at some point in their lives, so they make up for this high rate of attrition with their high breeding rates. This can also lead to overpopulation and conflict in some areas.

Population

Although exact population numbers are unknown, the muskrat has survived and thrived almost everywhere within its native and introduced range. According to the IUCN Red List, which tracks species conservation status, the muskrat is a species of least concern, meaning no special efforts are needed to bolster its numbers. Some muskrat populations appear to undergo a boom-and-bust cycle based on the availability of food in the area. As more muskrats are born, the amount of available vegetation goes down, which limits how many muskrats can survive. As population numbers go down, vegetation levels return to normal. In this way, the numbers tend to even out over time.