The muskrat (Ondatra zibethicus) is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over a wide range of climates and habitats. It has important effects on the ecology of wetlands, and is a resource of food and fur for humans.
Adult muskrats weigh 0.6–2 kg (1.3–4.4 lb), with a body length of 20–35 cm (8–10 in). They are covered with short, thick fur of medium to dark brown color. Their long tails, covered with scales rather than hair, are their main means of propulsion. Muskrats spend most of their time in the water and can swim under water for 12 to 17 minutes. They live in families, consisting of a male and female pair and their young. To protect themselves from the cold and from predators, they build nests that are often burrowed into the bank with an underwater entrance. Muskrats feed mostly on cattail and other aquatic vegetation but also eat small animals.
Ondatra zibethicus is the only species in the genus Ondatra and tribe Ondatrini. It 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, members of the genus Rattus. They are not closely related to beavers, with which they share habitat and general appearance.
Muskrats are found over most of Canada and the United States and a small part of northern Mexico. They were introduced to Europe in the beginning of the 20th century and have become an invasive species in northwestern Europe. They mostly inhabit wetlands, areas in or near saline and freshwater wetlands, rivers, lakes, or ponds. They are not found in Florida, where the round-tailed muskrat, or Florida water rat (Neofiber alleni), fills their ecological niche.
Their populations naturally cycle; in areas where they become abundant, they are capable of removing much of the vegetation in wetlands. They are thought to play a major role in determining the vegetation of prairie wetlands in particular. They also selectively remove preferred plant species, thereby changing the abundance of plant species in many kinds of wetlands.[2] Species commonly eaten include cattail and yellow water lily. Alligators are thought to be an important natural predator, and the absence of muskrats from Florida may in part be the result of alligator predation.
While much wetland habitat has been eliminated due to human activity, new muskrat habitat has been created by the construction of canals or irrigation channels (e.g., acequias), and the muskrat remains common and widespread. They are able to live alongside streams which contain the sulfurous water that drains away from coal mines. Fish and frogs perish in such streams, yet muskrats may thrive and occupy the wetlands. Muskrats also benefit from human persecution of some of their predators.
The muskrat is classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing it from being imported into the country.
The trematode Metorchis conjunctus can also infect muskrats.
In Europe, the muskrat has been included in the list of invasive alien species of Union concern (the Union list) since August 2, 2017.[21] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.
Muskrat (Ondatra zibethicus) - seen commonly in much of the USA, but rarely photographed and usually poorly