The North American river otter ("Lontra canadensis"), or the common otter, is an aquatic mammal native to only North America in the countries Canada, and the United States. River otters are a distant relative of the weasel family. North American river otters can reach a length of 3.9 ft and weigh 3 lbs. The river otter's life expectancy is 10 to 15 years in the wild and 25 years in captivity. The main habitat of the river otter are near freshwater rivers, streams, lakes, ponds, marshes, swamps, and coastal waters. They prefer fish, though they will eat amphibians such as frogs, turtles, and crayfish. They have also been reported to eat small mammals and birds.