Muskrat

The muskrat, known scientifically as Ondatra zibethicus, is a medium-sized semiaquatic rodent. Semiaquatic means these animals spend much of their lives in both water and on land.

They play a vital role in the ecology of wetlands like marshes, ponds, and rivers. By eating specific plants, they help maintain open areas in marshes. This activity provides essential habitats for various aquatic birds. Because they change the types of plants that grow, they are key to the health of prairie wetlands.

To thrive in the water, muskrats have evolved several specialized physical traits. They possess short, thick fur with two distinct layers to provide warmth in cold water. Their hind feet are partially webbed, acting as the primary means of propulsion.

Unlike many other rodents, they have a long, laterally compressed tail. This tail is covered in scales rather than hair and is flattened vertically. It functions much like a rudder to provide directional stability while swimming. Their bodies are also less sensitive to the buildup of carbon dioxide. This unique biological trait allows them to swim underwater for 12 to 17 minutes. They can even close their ears to keep water out while submerged.

Muskrats live in social family units. These groups typically consist of a male, a female, and their offspring. To protect themselves from predators and the cold, they build various types of shelters. Some muskrats burrow directly into the banks of lakes or streams. These burrows feature wide entrances that remain underwater to hide from danger. In marshy areas, they construct "push-ups," which are mounds made of mud and vegetation.

These push-ups can reach heights of up to 3 feet. In snowy climates, muskrats must plug their openings with vegetation and replace them daily. They also build feeding platforms using cut vegetation and branch structures.

The muskrat is the largest species within the subfamily Arvicolinae. This group includes 142 other rodent species, such as voles and lemmings. The muskrat belongs to the larger family Cricetidae, which contains hamsters and mice.

While they often share habitats with beavers, muskrats are much smaller. An adult muskrat weighs about 2.5 pounds and has a body length of about 16 inches. This weight is roughly four times that of a brown rat, even though they are only slightly longer. Their only living relative in the genus Ondatra is the round-tailed muskrat.

Muskrats are native to North America, including Canada, the United States, and northern Mexico. However, they have been introduced to other parts of the world. In the early 20th century, humans moved them to Europe and parts of Eurasia for the fur industry. In Europe, they are often classified as an invasive species. Their burrowing activities can damage river banks, dikes, and levees used for flood control. They can also damage crops like corn. In some areas, such as the former Soviet Union, the golden jackal is a major predator. During the winter of 1948–49, jackals destroyed 71% of muskrat houses in the Amu Darya river region.

These rodents serve as a massive food resource for a wide variety of animals. Predators include mink, foxes, wolves, coyotes, and even large birds like bald eagles. In the water, they are hunted by otters, snapping turtles, and large fish like pike. Even large mammals like moose and elk may eat the vegetation in muskrat push-ups during the winter. Muskrats are also prolific breeders. A female can produce two or three litters each year, with each litter containing six to eight young. These babies are born very small, weighing only about 0.3 ounces, and are initially hairless.

Humans have interacted with muskrats for many different reasons throughout history. Their fur is very warm and was once a major part of the fur industry. In the early 1900s, muskrat fur was sometimes dyed and sold as "Hudson seal" fur. Today, the Royal Canadian Mounted Police use muskrat fur for their winter hats. Some people also use them as a food source. However, muskrat populations are currently facing challenges. In the United States, populations have declined by at least half in 34 different states since the 1990s. In Rhode Island, the population is estimated to be only 15% of its former size.