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The river rat (Myocastor coypus) is a stocky and rotund rodent that also has two other oft-used monikers -- both "nutria" and "coypu." River rats are more comfortable and brisk underwater than otherwise, and as a result usually set up residence in damp habitats that have no shortage of water. As a species, river rats are extremely proficient swimmers. They are so relaxed with water in general that they often submerge their sustenance in it before beginning eating.
River Rat Physical Details
River rats have some outer similarities to rats, which is how they got their name. They have big heads, rounded, slender tails and inconspicuous ears and eyes. Their fur is brownish-gray, but their underbellies are markedly paler. River rats possess wide front teeth with prominent deep orange coloration. The nocturnal rodents generally weigh somewhere between 15 and 22 pounds, according to National Geographic. Their bodies are usually between 17 and 25 inches long.
River Rat Geography
River rats originally come from South America, although they have been brought to other continents throughout the world, including North America, for purposes of the fur trade. Within South America, river rats live in Uruguay, Brazil, Bolivia, Paraguay, Argentina and Chile.
River Rat Natural Habitat
River rats are semi-aquatic and their natural habitat choices definitely reflect that. They are often found by still creeks, by ponds, in marshes and in areas surrounding rivers and lakes. River rats generally gravitate toward freshwater settings whenever possible. However, it is not at all uncommon to spot them in water with more salinity. They are not big fans of moving around, and typically stay put in one area for the entire duration of their lifespans.
River rats retreat to burrows for resting purposes. Their burrows are rather diverse, as some appear to be just standard holes, while others are spacious and full of separate, intricate compartments. Sometimes, instead of carving out their own shelter, they instead occupy burrows established previously by other animals such as either armadillos or muskrats. They also employ pre-existing burrows as nesting locales, as well. River rats often use their burrows to stay hidden from predators, but also to keep their bodies warmer in the midst of frigid temperatures.
- Tennessee Watchable Wildlife: Coypu (Nutria)
- USGS: Nutria
- University of Michigan Animal Diversity Web: Myocastor coypus
- Natural Science Research Laboratory: Nutria
- IUCN Red List of Threatened Species: Myocastor coypus
- USDA - APHIS: Nutria in Louisiana
- National Geographic: Nutria
- Virginia Department of Game and Inland Fisheries: Nutria
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