NORTHERN RIVER OTTER

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'. It is a common animal in North American waterways. However, its numbers have significantly dropped since Europeans came to the Americas.^[1]

Contents

Taxonomy

Description

Distribution and habitat

Conservation status

Behavior

Diet

Reproduction

Care in captivity

References

External links

Taxonomy

The Northern Rver Otter is a species of otter, or the family ''lutrinae''. It is a member of the genus ''lontra'', which is comprised of North American otters. It was previously included, with the other members of ''lontra'', included in the genus ''lutra'', but was placed in a newly-created genus when it was determined that the North American otters are more closely related to the genera ''Lutrogale'' and ''Pteronura'' than to the other species in ''Lutra''.

Description

The Northern River Otter has a streamlined, muscular body 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 its 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. The river otter has have a round, small head, short yet powerful legs, and large whiskers. Otters display sexual dimorphism, as the male otter is larger than the female. Its fur is glossy and dark brown fur, and the throat is often silver grey. The otter is a powerful swimmer, but can also travel quickly on land and often propel itself into a rapid slide on its belly on snow or ice; it also likes to slide down river banks into the water. The North American River Otters has nostrils which close underwater and its fur is soft and dense; both of these adaptations help it to have extended excursions underwater.
On land, a Northern River Otter can run up to 18 miles per hour. Its life span is 10-15 years in the wild, but it may live up to 25 years in captivity. (Fact Sheet: North American River Otter)

Distribution and habitat

The Northern River Otter is found throughout North America, inhabiting inland waterways and coastal areas in Canada, Alaska, the Pacific Northwest, the Atlantic states, and the Gulf of Mexico.
The Northern river otter is found in a wide variety of aquatic habitats, both freshwater and costal marine, including lakes, rivers, inland wetlands, coastal marshes, and estuaries. It can tolerate a great range of temperature and elevations; its main requirements are a steady food supply and easy access to a body of water. However, the the Northern river otter is sensitive to pollution, and will disappear from polluted areas. ^[2]
Like other otters, the Northern river otter lives in a den. The den is constructed in the burrows of other animals, or in natural hollows, such as under a log or in river banks. An underwater entrance or an above-ground entrance leads to a nest chamber which is lined with leaves, grass, moss, bark, and hair.^[3] It often uses dens built by other animals, sometimes killing beavers or muskrats to take over their lodges.

Conservation status

Northern River Otters are trapped for their highly-prized fur. Over-harvest in the 1800s has led to its disappearance from many parts of its 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. Since the discovery of the Americas, hunters have captured and killed the otters for their pelts. Hunting still continues today, otter pelts being worth over $100 (USD) each. Over 30,000 otter pelts are sold each year in the United States and Canada.

Efforts have been made to bring the otter back from endangerment. Since 1986, the National Park Service has reintroduced over 100 Northern River Otter back into the wild. (Linzey, 2002)

Behavior

The Northern River Otter is a highly active predator, like its relatives, the weasels. It is very playful, chasing, sliding, swimming, jumping, wrestling. This makes it popular for zoo exhibits. However, otters are not friendly towards humans if raised in captivity. Generally a captive-raised river otter becomes very aggressive towards humans when it reaches sexual maturity, and thus it does not make a good pet. 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.

Diet

The Northern River Otter mainly eats 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. The Northern River Otter is capable of swimming in circles, which creates a whirlpool-like motion that brings fish from the bottom of the water up to the top. It is generally nocturnal or crepuscular, but is active during the day where undisturbed by human activity. It uses musk and urine to mark the land bordering their territories in a behavior called sprainting.

Reproduction

The Northern River Otter female evicts her mate while babies are still young, but the male will return later however to help care for the young 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.

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.

References

★ Database entry includes justification for why this species is of least concern

External links

★ An Otter Family Album, a thorough chronicle of 23 years of otter colony observations by J. Scott Shannon

★ North American River Otter species profile by the Nature Conservancy

★ Nature: Yellowstone Otters, educational resources from the Public Broadcasting System

★ Lontra canadensis from the University of Michigan Museum of Zoology's "Animal Diversity Web"

★ North American River Otter fact sheet from the Woodland Park Zoo in Seattle, Washington (USA)

★ photo gallery at Otternet.com

★ River Otter species information from AnimalsArchive.com