Nutria vs Muskrat: How to Tell Them Apart

If you spot one in the water, size is your first and most reliable tell. A nutria will be obviously larger, about the size of a small dog, while a muskrat is cat-sized. From a distance, a nutria looks heavy and muscular where a muskrat looks slender. Your second tell is the front teeth if you get close enough. Nutrias have large, bright orange front teeth that stick out prominently. Muskrats have smaller, paler teeth. Your third tell is the tail. Nutrias carry a long, round tail that looks thick and rope-like. Muskrats have a long tail that is noticeably flattened, almost like a paddle or a rudder. Watch how they move too. Nutrias are slower swimmers but powerful diggers. Muskrats are faster and more agile in water.

Nutrias and muskrats are both rodents, but nutrias are roughly four to five times heavier. An adult nutria weighs about 15 to 20 pounds, while a muskrat weighs only 2 to 4 pounds. This size difference is your clearest field mark. Nutrias have a stocky, muscular build with thick hind legs and a broad body. Their necks are noticeably thicker than a muskrat's. Muskrats are built for streamlined movement in water. They have smaller limbs, a narrower body, and a lighter frame overall. When both animals are hauled out on a bank, the size contrast is dramatic. A nutria looks like a large furry potato, while a muskrat looks like a smaller, sleeker version.

Nutrias are invasive in North America. They originally came from South America and escaped from fur farms in the early 1900s. Today they live in southern and western states, especially in Louisiana, Texas, California, and the Pacific Northwest. You can find nutrias at /wildlife/washington/nutria and /wildlife/wisconsin/nutria. Muskrats are native and live across most of wetland habitats in North America, from the Great Lakes to coastal marshes. Muskrats avoid the warmest southern regions. In the central US, both animals share some wetland habitat, but nutrias prefer larger, more open marshes while muskrats thrive in smaller wetlands, rivers, and even drainage ditches. Learn more at /wildlife/wyoming/muskrat or /wildlife/wisconsin/muskrat.

Nutrias are grazers and browsers. They feed on cattails, water lilies, sedges, and cultivated crops. They dig deep burrows in banks and levees, which can cause serious erosion problems. Nutrias are somewhat sociable and often seen in small groups. They are active throughout the day and night. Muskrats also eat aquatic plants but are more selective feeders. Instead of burrowing, many muskrats build lodges similar to beaver lodges, or they build push-ups, which are feeding shelters made from marsh plants. Some muskrats do burrow into banks. Muskrats are secretive and mainly nocturnal, so you are more likely to see evidence of them like tracks and lodges than to see the animals themselves. Both are excellent swimmers, but muskrats are faster and more graceful in water.

Start with size. If the animal was obviously large, heavy, and dog-like, you saw a nutria. If it was small and cat-sized, it was a muskrat. If you saw the teeth and they were bright orange, that was definitely a nutria. Pale or white teeth mean muskrat. Check the tail if you can. A thick, round tail points to nutria. A flat, paddle-like tail means muskrat. If you saw the animal's lodge or evidence of feeding, muskrats build visible structures from plant material, while nutrias leave burrows and grazing trails. Geographic location helps too. If you were in the southern US, Louisiana, or Texas, a nutria is more likely. If you were in the upper Midwest or Great Lakes region, you were probably watching a muskrat. Visit /wildlife to explore regional sightings and distributions.

The biggest myth is that nutrias and muskrats are the same animal or are known by different regional names. They are completely different species that evolved separately, though both are semi-aquatic rodents. Another common mix-up is thinking muskrats are just young nutrias. A large muskrat and a small nutria do not overlap in size. Another myth is that nutrias are native to North America. They are recent arrivals and invasive. Some people believe muskrats are invasive too, but they have lived here for thousands of years. One final myth is that nutrias and muskrats compete directly for the same food and habitat. While there is some overlap, they prefer different plant types and water conditions, so they can coexist without direct competition.