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Species Information
OK Wildlife Control® , LLC * 19721 East 3rd Street * Tulsa, OK * USA * 74108 Phone: (918) 739-4382
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River Otter
OK Wildlife Control®, LLC
Phone Number: (918) 739-4382
19721 East 3rd Street
Tulsa, OK 74108
Email:
info@oktrapsupply.com
Other Websites:
http://oklahomawildlifecontrol.com
http://okwildlifecontrol.com
OK Wildlife Control®, L.L.C. contractors and
employees utilize and practice BMPs (Best
Management Practices) whenever possible and
practical. These practices assist in maximizing
removal procedures while minimizing the stresses
caused to wildlife.

Best Management Practices (BMPs) for Trapping
in the United States was written by the U.S. Trap
Testing Technical Work Group of the International
Association of Fish and Wildlife Agencies.
Development of this document would not have
been possible without the cooperation and
participation of many state wildlife agencies,
expert trappers, and trapper organizations. For a
complete BMPs listing,
click here.
BMPs
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Identification

River otters Lutra canadensis, are best known for their continuous and playful behavior, their
aesthetic value, and the value of their durable, high-quality fur. They have long, streamlined bodies,
short legs, and a robust, tapered tail, all of which are well adapted to their mostly aquatic habitat.
They have prominent whiskers just behind and below the nose, thick muscular necks and
shoulders, and feet that are webbed between the toes. Their short but thick, soft fur is brown to
almost black except on the chin, throat, cheeks, chest, and occasionally the belly, where it is
usually lighter, varying from brown to almost beige.

Adult males usually attain lengths of nearly 48 inches (122 cm) and weights of about 25 pounds
(11.3 kg), but may reach 54 inches (137 cm) and 33 pounds (15 kg). Their sex can be readily
distinguished by the presence of a baculum (penile bone). Females have 4 mammae on the upper
chest and are slightly smaller than males. Female adults measure about 44 inches (112 cm) and
weigh 19 pounds (8.6 kg). The mean weights and sizes of river otters in southern latitudes tend to
be lower than those in latitudes farther north.

Range and Habitat

River otters occur throughout North America except the arctic slopes, the arid portions of the
Southwest, and the intensive agricultural and industrialized areas of the midwestern United States.
Their precolonial range apparently included all of North America except the arid Southwest and the
northernmost portions of Alaska and Canada. Otter populations are confined to water courses,
lakes, and wetlands, and therefore, population densities are lower than those of terrestrial species.
Their extirpation from many areas is believed to have been related more to poisoning by pesticides
bio-magnified in fishes, and to the indirect adverse effects of water pollution on fish, their main food,
than to excessive harvest. The loss of ponds and other wetland habitat that resulted from the
extirpation of beaver in the late 1800s may have adversely affected continental populations of river
otters more than any other factor. Increases in the range and numbers of river otters in response to
the return of beaver has been dramatic, particularly in the southeastern United States. Recent
releases totaling more than 1,000 otters have been made in Arizona, Colorado, Iowa, Kansas,
Kentucky, Missouri, Nebraska, Oklahoma, Pennsylvania, Tennessee, and West Virginia in efforts to
reestablish local populations.

River otters are almost invariably associated with water (fresh, brackish, and salt water), although
they may travel overland for considerable distances. They inhabit lakes, rivers, streams, bays,
estuaries, and associated riparian habitats. They occur at much higher densities in regions of the
Great Lakes, in brackish marshes and inlets, and in other coastal habitats than farther inland. In
colder climates, otters frequent rapids and waterfall areas that remain ice-free. Vegetative cover and
altitude do not appear to influence the river otter's distribution as much as do good or adequate
water quality, the availability of forage fish, and suitable denning sites.

Food Habits

The diet of the river otter throughout its range is primarily fish. Numerous species and varieties of
fresh and anadromous fishes are eaten, but shellfish, crayfish, amphibians, and reptiles are also
frequently eaten, as are several species of crabs in coastal marshes. Mammals and birds are rarely
eaten. Consumption of game fishes in comparison to nongame (rough) fishes is generally in
proportion to the difficulty, or ease, with which they can be caught. Because of the availability of
abundant alternate food species in warm water, losses of the warm water sport fishes are believed
minor compared to losses river otters can inflict on cold water species such as trout and salmon.


General Biology, Reproduction, and Behavior

The reproductive biology of river otters and all other weasels is complex because of a characteristic
known as delayed implantation. Following breeding and fertilization in spring, eggs (blastocysts)
exist in a free-floating state until the following winter or early spring. Once they implant, fetal growth
lasts 60 to 65 days until the kits are born, usually in spring (March through May) in most areas. In
the southern portion of the range the dates of birth occur earlier, mostly in January and February,
implying implantation in November and December. Litters usually contain 2 to 4 kits, and the female
alone cares for the young. They usually remain together as a family group though the fall and into
the winter months. Sexual maturity in young is believed to occur at about 2 years of age in females,
but later in males.

River otters are chiefly nocturnal, but they frequently are active during daylight hours in undisturbed
areas. Socially, the basic group is the female and her offspring. They spend much of their time
feeding and at what appears to be group play, repeatedly sliding down steep banks of mud or snow.
They habitually use specific sites (toilets) for defecation. Their vocalizations include chirps, grunts,
and loud piercing screams. They are powerful swimmers and are continuously active, alert, and
quick characteristics that give them immense aesthetic and recreational value. Their webbed feet,
streamlined bodies, and long, tapered tails enable them to move through water with agility, grace,
and speed. Seasonally, they may travel distances of 50 to 60 miles (80 to 96 km) along streams or
lake shores, and their home ranges may be as large as 60 square miles (155 km2). Males have
been recorded to travel up to 10 miles (16 km) in 1 night.

River otters use a variety of denning sites that seem to be selected based on availability and
convenience. Hollow logs, rock crevices, nutria houses, and abandoned beaver lodges and bank
dens are used. They will also frequent unused or abandoned human structures or shelters. Natal
dens tend to be located on small headwater branches or streams leading to major drainages or
lakes.
Damage and Damage Identification

The presence of river otter(s) around or in a fish hatchery, aquaculture, or fish culture facility is a good indication that a damage problem is imminent. Otter
scats or toilets that contain scales, exoskeletons, and other body parts of the species being produced is additional evidence that damage is ongoing.
Uneaten parts of fish in shallow water and along the shore is evidence that fish are being taken. Otters usually eat all of a small catfish except for the head
and major spines, whereas small trout, salmon, and many of the scaled fishes may be totally eaten. Uneaten carcasses with large puncture holes are likely
attributable to herons. River otters can occasionally cause substantial damage to concentrations of fishes in marine aquaculture facilities. Often the damage
involves learned feeding behavior by one or a family of otters.

Legal Status

The river otter is listed in Appendix II of the Convention on International Trade in Endangered Species of Flora and Fauna (CITES). Its inclusion in this
appendix subjects it to international restrictions and state/province export quotas because of its resemblance to the European Otter. Moreover, the river otter
is totally protected in 17 states. Twenty-seven states have trapping seasons, and four states and two provinces have hunting seasons. The Oklahoma
Wildlife Control® , LLC., is a nuisance & predatory wildlife solutions and service company, with a number of specialties. However, OWC is not an animal
rescue organization. If you have problems with domestic cats and dogs, we suggest that you contact your local animal shelter for assistance. Thank you.
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