Ronin (Aizawa Romance)

(i) River Otter

The North American river otter, a member of the subfamily Lutrinae in the weasel family (Mustelidae), is equally versatile in the water and on land. It establishes a burrow close to the water's edge in river, lake, swamp, coastal shoreline, tidal flat, or estuary ecosystems. The den typically has many tunnel openings, one of which generally allows the otter to enter and exit the body of water. Female North American river otters give birth in these burrows, producing litters of one to six young.[2]

North American river otters, like most predators, prey upon the most readily accessible species. Fish is a favored food among the otters, but they also consume various amphibians (such as salamanders and frogs[3]), freshwater clams, mussels, snails, small turtles and crayfish. The most common fish consumed are perch, suckers, and catfish.[4] Instances of North American river otters eating small mammals, such as mice and squirrels, and occasionally birds have been reported as well. There have also been some reports of river otters attacking and even drowning dogs.[5][6][7]

The range of the North American river otter has been significantly reduced by habitat loss, beginning with the European colonization of North America. In some regions, though, their population is controlled to allow the trapping and harvesting of otters for their pelts. North American river otters are very susceptible to the effects of environmental pollution, which is a likely factor in the continued decline of their numbers. A number of reintroduction projects have been initiated to help halt the reduction in the overall population.[8]

The North American river otter was first described by German naturalist Johann Christian Daniel von Schreber in 1777.[9] The mammal was identified as a species of otter and has a variety of common names, including North American river otter, northern river otter, common otter and, simply, river otter.[9] Other documented common names are American otter, Canada otter, Canadian otter, fish otter, land otter, nearctic river otter, and Prince of Wales otter.[10]

The North American river otter was first classified in the genus Lutra; Lutra was the early European name. The species name was Lutra canadensis.[9] The species epithet canadensis means "of Canada".[11]

In a new classification, the species is called Lontra canadensis, where the genus Lontra includes all the New World river otters.[12] Molecular biological techniques have been used to determine when the river otter and the giant otter (Pteronura brasiliensis) of South America diverged. These analyses suggest they diverged in the Miocene epoch 23.03 to 5.33 million years ago (Mya), which is "much earlier" than indicated in the fossil record.[13] Fossils of a giant river otter dating back 3.5 Mya have been found in the US Midwest; however, fossils of the modern river otter did not appear in North America until about 1.9 Mya.[14] The earliest known fossil of Lontra canadensis, found in the US Midwest, is from the Irvingtonian stage (1,800,000 to 300,000 years ago).[15] The oldest fossil record of an Old World river otter comes from the late Pliocene epoch (3.6 to 1.8 Mya).[16] The New World river otters originated from the Old World river otters following a migration across the Bering Land Bridge, which existed off and on between 1.8 million and 10,000 years ago. The otters migrated to North America and southwards again across the Panamanian Land Bridge, which formed 3 Mya.[10]

Subspecies    Edit

Listed alphabetically:[17]

L. c. canadensis (Schreber, 1777) – (eastern Canada, U.S., Newfoundland)

L. c. kodiacensis (Goldman, 1935) – (Kodiak Island, Alaska)

L. c. lataxina (Cuvier, 1823) – (U.S.)

L. c. mira (Goldman, 1935) – (Alaska, British Columbia)

L. c. pacifica (J. A. Allen, 1898) – (Alaska, Canada, northern U.S., south to central California, northern Nevada, and northeastern Utah)