Muskrat

The muskrat (Ondatra zibethicus), the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats. It plays an important role in nature and is a resource of food and fur for humans, as well as being an introduced species in much of its present range.
The muskrat is the largest species in the subfamily Arvicolinae, which includes 142 other species of rodents, mostly voles and lemmings. Muskrats are referred to as "rats" in a general sense because they are medium-sized rodents with an adaptable lifestyle and an omnivorous diet. They are not, however, so-called "true rats", that is, members of the genus Rattus. Wikipedia