Northern River Otter
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[Photo] North American River Otters, Lontra canadensis (per Schreber, 1777. More commonly used, but allegedly incorrect latin name: Lutra canadensis). Taken at San Francisco Zoo on 08/29/2005 by Dmitry Azovtsev - http://fotki.azovtsev.com/

The Northern River Otter, Lontra canadensis, is a North American member of the Mustelidae or weasel family. It is also known as the North American River Otter. This species can be found all across North America, inhabiting inland waterways and coastal areas in Canada, Alaska, the Pacific Northwest, the Atlantic states, and the Gulf of Mexico. However, their numbers have significantly dropped since Europeans came to the Americas. (Linzey, 2002)

Description
L. canadensis have streamlined, muscular bodies with short legs, webbed toes and a long muscular tail. The North American river otter’s body measure is somewhere between 25.98" to 42.13", and their tail measure is between 12.40" to 18.11" (a river otter’s tail makes up 30 to 40% of the total length of its body). It can weigh between 6 and 31 pounds. River otters have a round and small head and eyes, short yet powerful legs, and have large whiskers. Otters have sexual dimorphism, as the male is larger than the female. They have glossy dark brown fur and their throat is often silver grey. Otters are powerful swimmers, but can also travel quickly on land and often propel themselves into a rapid slide on their bellies on snow or ice; they also like to slide down river banks into the water. North American river otters have nostrils that close underwater and their fur is soft and dense; both of these adaptations help them to live underwater. On land, the river otters can run up to 18 miles per hour. Their current life span is 10-15 years in the wild, but they can live up to 25 years in captivity. (Fact Sheet: North American River Otter)

Habitat
Northern river otters have their dens on land, and they hunt in a wide variety of aquatic habitats, including lakes, rivers, inland wetlands and swamps, coastal marshes and even the open ocean. In many areas of the United States and Canada, the damming activities of the beaver creates ideal habitat for otters.

Diet and natural history
Otters mainly eat fish but also eat insects, frogs, crustaceans and sometimes small mammals. On occasion some larger river otters will attack and kill water birds such as ducks, geese, and even herons. They are capable of swimming in circles, which creates a whirlpool-like motion that brings fish from the bottom of the water up to the top. They are generally more active at night, dusk and dawn, but are active during the day where undisturbed by human activity. They use musk and urine to mark the land bordering their territories. They often use dens built by other animals, sometimes killing beavers or muskrats to take over their lodges. Females evict males while babies are still young, the male will return later however to help care for them when half-grown. (Dewey, 2004) North American river otters usually mate once a year in late winter or usually early spring. Males often mate with several females during the breeding season. They have a gestation period of 2 months, and the pups are weaned for 3 months. The size of the litter can range from 1-6 pups, but usually there are only 2-3. (Dewey, 2004) There is a delay in the implantation of the fertilized egg, so that the young are born in late winter or early spring. Mating occurs in water.

Personality
Like their relatives, the weasels, river otters are highly active predators. If an otter is not sleeping, it's moving. They are very playful, chasing, sliding, swimming, jumping, wrestling. This makes them popular for exhibits. However, they are not friendly towards humans if raised in captivity. Usually a captive raised river otter becomes very aggressive towards humans when it reaches sexual maturity, and thus they do not make good pets. There are times when otters have remained tame through their adult life, or have been taken from the wild as adults. However, "tame" is a relative term, even the most human-friendly otter will still bite and scratch, sometimes quite badly. They can be highly curious animals and have been known to follow trout fisherman along the opposite bank.

Conservation status
Otters are trapped for their highly-prized fur. Over harvest in the 1800s has led to their disappearance from many parts of their historical range. Trapping is still permitted in some areas where otters remain abundant. In other areas, the otter is being restored to places where it may have long since been extirpated, such as the Hudson River. The North American river otter is not a nationally endangered species, but it is endangered in many states and it is threatened in others. Over-hunting, habitat destruction, and inadequate laws protecting the North American river otter are major factors where otters remain threatened. Ever since the discovery of the americas, hunters have captured and killed the otters for their pelts. Hunting still continues today, their pelts being worth over $100 (USD) each. Over 30,000 otter pelts are sold each year in the United States and Canada.

Otters eat many game fish in the habitats that they live in. These game fish are better fish that people fish for food. Efforts have been made to bring the otter back from endangerment. Since 1986, the National Park Service has reintroduced over 100 North American river otters back into the wild. (Linzey, 2002)

Care In Captivity
Otters are only suited for professional exhibits or care. Their diet is flexible. Some groups feed their otters a variety of fresh water creatures in addition to live fish, while others live on a diet of pre-killed rodents. They need access to fresh water deep enough to swim and play in, and this water will need to be changed regularly or filtered. Some groups add chlorine to the water to reduce bacteria and algae growth, but this may result in skin problems for the otter. As they are very active, they are easy to train for medical exams, demonstrations, and behavioral enrichment. Common enrichment objects include ice with food frozen in it, floating balls, and segments of wide pipe.

http://en.wikipedia.org/wiki/Northern_River_Otter

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