(Last Updated On: March 20, 2021)

The North American river otter, scientific name Lontra canadensis, also called the northern river otter or widespread otter is a semiaquatic mammal endemic to the North American continent present in and alongside its waterways and coasts. In this article, I am going to talk about North American River Otter habitat, range, size, baby, tracks, facts, adaptations, teeth, predators, etc.

An adult North American river otter can weigh between 5.Zero and 14 kg (11.Zero and 30.9 lb). The river otter is protected and insulated by a thick, water-repellent coat of fur.

North American River Otter Profile

Most researchers particularly specializing in otters hardly ever truly see any wild otters. Otters are very secretive and shy and would somewhat run away than assault.

Because they’re nearly at all times very near a body of water, in the event that they hear a human they will soar into the water rapidly and make a quick getaway.

Instead of truly attempting to identify an otter, researchers search for what they call “latrine sights.” Otters will at all times go back to the identical few spots of their residence range to defecate; that is what is called a latrine sight.

Even the otters in the zoo have chosen their very own latrine sights. Researchers additionally depend on game cams that they set as much as catch footage and movies of otters within the night.

The torpedo-formed body the otter has permits it to chop by way of the water in an easy and quick method. The otter can shut its ears and nostrils when diving. A bunch of otters is named a “romp” of otters.

North American River Otter

The North American river otter, a member of the subfamily Lutrinae within the weasel family (Mustelidae), is equally versatile within the water and on land.

It establishes a burrow near the water’s edge in the river, lake, swamp, coastal shoreline, tidal flat, or estuary ecosystems.

The den sometimes has many tunnel openings, certainly one of which typically permits the otter to enter and exit the body of water. Female North American river otters give start in these burrows, producing litters of 1 to 6 younger.

North American river otters, like most predators, prey upon essentially the most readily accessible species. Fish is a well-liked meal among the many otters, however in addition they devour numerous amphibians (resembling salamanders and frogs), freshwater clams, mussels, snails, small turtles, and crayfish.

The most typical fish consumed are perch, suckers, and catfish. Instances of North American river otters consuming small mammals, resembling mice and squirrels, and sometimes birds have been reported as properly. There have additionally been some reviews of river otters attacking and even drowning dogs.

The range of the North American river otter has been considerably lowered by habitat loss, starting with the European colonization of North America. In some areas, although, their inhabitants are managed to permit the trapping and harvesting of otters for his or her pelts.

North American river otters are very prone to the results of environmental air pollution, which is a possible issue within the continued decline of their numbers. A lot of reintroduction initiatives have been initiated to assist halt the discount within the total inhabitants.


The North American river otter is discovered all through North America, inhabiting inland waterways and coastal areas in Canada, the Pacific Northwest, the Atlantic states, and the Gulf of Mexico.

North American river otters additionally at present inhabit coastal areas all through the United States and Canada. North American river otters additionally inhabit the forested areas of the Pacific coast in North America.

The species can be present all through Alaska, together with the Aleutian Islands, and the north slope of the Brooks Range.

North American River Otter Description

The North American river otter is a stocky animal of 5 to 14 kilograms (11 to 31 lb), with brief legs, a muscular neck (no smaller than the pinnacle), and an elongated body that’s broadest on the hips.

They have long bodies and long whiskers which can be used to detect prey in darkish waters. An average adult male weighs about 11.3 kilograms (25 lb) towards the feminine’s average of 8.Three kilograms (18 lb).

Its body size ranges from 66 to 107 centimeters (26 to 42 in). About one-third of the animal’s total size consists of a long, tapered tail. Tail lengths range from 30 to 50 centimeters (12 to 20 in).

Large male North American river otters can exceed a weight of 15 kilograms (33 lb). It differs from the European otter by its longer neck, narrower visage, the smaller area between the ears, and shorter tail.

A broad muzzle is discovered on the North American river otter’s flat head, and the ears are round and inconspicuous. The rhinarium is naked, with an obtuse, triangular projection.

Eyes are small and positioned anteriorly. A brief, broad rostrum for exhaling and a long, broad skull outline the comparatively flat skull.

The North American river otter’s nostrils and ears shut throughout submersion, maintaining water from getting into them. Its vibrissae (whiskers) are long and thick, enhancing sensory notion underwater and on land.

The North American river otter is bodily well-equipped for aquatic life. The ears are brief, the neck is similar diameter as the pinnacle, the legs are brief and highly effective, the toes are totally webbed, and the tail (one-third of body size) is tapered.

These qualities give the North American river otter a streamlined profile in the water, however, cut back agility on land. The scent and listening to skills of the North American river otter are acute.

The North American river otter has a fragile sense of contact within the paws along with great dexterity. North American river otters characteristically strategy inside just a few feet of a ship or an individual onshore as a result of they’re near-sighted, a consequence of vision tailored for underwater sight.

North American river otters have transparent nictitating membranes to guard their eyes whereas swimming.

The right lung of the North American river otter is bigger than the left, having 4 lobes in contrast with two for the left. Reduced lobulation of the lungs is presumed to be adaptive for underwater swimming.

In addition, the size of the trachea of the North American river otter is intermediate between that of terrestrial carnivores and marine mammals.

The implied tracheal size of the North American river otter is 15.3 cm (6.0 in), or 23.2% of the body size. A shorter trachea might enhance air trade and improve lung airflow in diving mammals.

Most mustelids, together with otters, have specialized teeth, together with sharp canines and carnassials that inflict deadly bites to prey.

Also, North American river otters have massive molars used for crushing onerous objects, such because the shells of mollusks. An adult North American river otter has a total of 36 teeth. Additional premolars could also be present. The dental system is

North American River Otter


The fur of the species is brief (guard hairs average 23.8 mm (0.94 in)), with a density of about 57,800 hairs/cm2 (373,000 hairs/in2) within the midback part. The pelage has a high luster and varies from light brown to black.

The throat, chin, and lips are grayer than the remainder of the body. The fur of senescent river otters might turn out to be white-tipped, and uncommon albinos might happen.


The North American river otter is sexually dimorphic. Males are, on average, 5% bigger than females. In Idaho, juvenile, yearling, and adult males averaged 8, 11, and 17% heavier, respectively, than females of the identical age.

A clinal discount in size might exist from north to south alongside the Pacific coast, however not from east to west.


Although generally referred to as a “river otter”, the North American river otter is present in all kinds of aquatic habitats, each freshwater, and coastal marine, together with lakes, rivers, inland wetlands, coastal shorelines, marshes, and estuaries.

It can tolerate a great range of temperature and elevations. A North American river otter’s principal necessities are a steady meal supply and quick access to a body of water. However, it’s delicate to air pollution and can disappear from tainted areas.

Like different otters, the North American river otter lives in a holt, or den, constructed within the burrows of different animals, or in natural hollows, resembling beneath a log or in river banks.

An entrance, which can be underwater or above ground, results in a nest chamber lined with leaves, grass, moss, bark, and hair. Den sites embody burrows dug by woodchucks (Marmota monax), red foxes (Vulpes vulpes), nutria (Myocastor coypus), or beaver and muskrat lodges.

North American river otters additionally might use hole timber or logs, undercut banks, rock formations, backwater sloughs, and flood particles. The use of den and resting sites are mainly opportunistic, though places that present safety and seclusion are most popular.


North American river otters dwell an average of 21 years of age in captivity,22] however they will attain 25 years of age. In the wild, they usually dwell about Eight to 9 years, however are able to reside as much as 13 years of age.


North American river otters are energetic year-round and are most energetic at night and through crepuscular hours. They turn into a lot more nocturnal within the spring, summer, and fall seasons, and more diurnal throughout winter.

They might migrate because of meal shortages or environmental situations, however, they don’t migrate yearly. North American river otters solely settle in areas that encompass vegetation, rock piles, and enough protection.

North American River Otter Locomotion

North American river otters swim by quadrupedal paddling, forelimb paddling, alternate hind-limb paddling, simultaneous hind-limb paddling, or body and tail dorsoventral undulation.

The tail, which is stout and bigger in floor space than the limbs, is used for stability whereas swimming and for brief bursts of fast propulsion. While swimming on the floor, the dorsal portion of the North American river otter’s head, together with nostrils, ears, and eyes, is uncovered above water. It should stay in the movement to take care of its place on the floor.

On land, the North American river otter can stroll, run, certain, or slide. Footfalls throughout strolling and working comply with the sequence of left limb, right limb, right limb, left limb. During strolling, the limbs are moved in a plane parallel to the long axis of the body.

Bounding is the result of the simultaneous lifting of the limbs off the ground. As the front feet make contact with the ground, the back feet are lifted and land the place the front paws first contacted the ground, producing a pattern of tracks in pairs typical of most mustelids. Sliding happens totally on even surfaces of snow or ice, however can even happen on grassy slopes and muddy banks.

Sliding throughout snow and ice is a fast and efficient technique of travel, and otters touring over mountain passes, between drainages, or descending from mountain lakes typically slide repeatedly for a number of hundred meters.

Rear leg paddling allows steady sliding the place gravity is an inadequate or an opposing pressure. During winter, the North American river otters closely use openings within the ice and should excavate passages in beaver dams for accessing open water.

North American river otters are extremely mobile and have the capability of touring as much as 42 km (26 mi) at some point. Daily actions of yearling women and men in Idaho averaged 4.7 and a pair of.4 km (2.9 and 1.5 mi) in spring, 5.1 and 4.0 km (3.2 and a pair of.5 mi) in summer, and 5.0 and 3.3 km (3.1 and a pair of.1 mi) in autumn, respectively.

Daily actions of family teams averaged 4.7, 4.4, and a pair of.4 km (2.9, 2.7, and 1.5 mi) in spring, summer, and winter, respectively. Both males and family teams travel drastically much less throughout winter.


North American river otters are famed for his or her sense of play. Otter plays principally consists of wrestling with conspecifics. Chasing can be a typical game.

North American river otters rely on the play to be taught survival skills resembling combating and looking. However, playful behavior was present in solely 6% of 294 observations in a study in Idaho and was restricted principally to immature otters.

North American River Otter


Prey is captured with a fast lunge from ambush, or more hardly ever, after a sustained chase. North American river otters can stay underwater for practically 4 minutes, swim at speeds approaching 11 km/h (6.8 mph), dive to depths nearing 20 m (22 yds), and travel as much as 400 m (440 yds) whereas underwater.

Several North American river otters might even cooperate whereas fishing. Small fish are eaten on the floor, but bigger ones are taken to the shore to be consumed. Live fish are sometimes eaten from the pinnacle.

A highly energetic predator, the North American river otter has tailored to looking in the water and eats aquatic and semiaquatic animals. The vulnerability and seasonal availability of prey animals primarily govern its meals habits and prey selections.

This availability is influenced by the next components: detectability and mobility of the prey, habitat availability for the varied prey species, environmental components, resembling water depth and temperature, and seasonal modifications in prey provide and distribution in correspondence with otter foraging habitat.

North American River Otter Diet

The diet of the North American river otter could be deduced by analyzing both stools obtained within the discipline, or intestine contents faraway from trapped otters.

Fish are the first part of the North American river otter’s diet all through the year. Every research executed on the food habits of the North American river otter has recognized various fish species as being the first part of its diet.

In the wild, these otters eat a wide range of fish, crayfish, frogs, and aquatic invertebrates together with an occasional bird or rodent. They prey most frequently on slower fish, resembling catfish, carp, and sculpins.

They use their delicate whiskers which assist them to locate prey and catch their prey with their mouth, utilizing their paws to carry on to the prey if wanted. In the Zoo, they eat meat, eggs, carrots, number of fish (trout, catfish, herring, capelin, smelt).

North American River Otter Social Behavior

The North American river otter is more social than most mustelids. In all habitats, their primary social group is the family, consisting of an adult feminine and her progeny.

Adult males additionally generally set up enduring social groupings, some documented to comprise as many as 17 people. In coastal areas, males might stay gregarious even through the estrous interval of females.

Family teams might embody helpers, which could be made up of unrelated adults, yearlings, or juveniles. Male North American river otters disperse from such family teams more typically than females.

When females go away, they have an inclination to maneuver a lot additional away (60–90 km or 37–56 mi) than males (as much as 30 km or 19 mi), which have a tendency to maneuver shorter distances.

Male North American river otters don’t appear to be territorial, and newly dispersing males might be part of established male teams. On occasion, teams of unrelated juveniles are noticed.

North American river otters residing in teams hunt and travel collectively, use the identical dens, resting sites, and latrines, and carry out allogrooming. In freshwater methods, teams happen most frequently in autumn and through early winter.

From mid-winter by way of the breeding season, adult females transfer and den alone. River otters usually are not territorial, however particular person North American river otters of various teams painting mutual avoidance.

Home ranges of males are bigger than these of females, and each sex exhibit intra- and intersexual overlap of their domains.


Communication amongst North American river otters is completed primarily by olfactory and auditory indicators. Scent marking is crucial for intergroup communication.

The North American river otter scent-marks with feces, urine, and probably anal sac secretions. Musk from the scent glands might also be secreted when otters are frightened or indignant.

North American river otters can produce a snarling growl or hissing bark when bothered, and a shrill whistle when in ache. When at play or touring, they often give off low, purring grunts.

The alarm call, given when shocked or distressed by potential hazard, is an explosive snort, made by expelling air by way of the nostrils. North American river otters additionally might use a birdlike chirp for communication over longer distances, however, the commonest sound heard amongst a bunch of otters is low-frequency chuckling.

North American River Otter Life cycle

North American river otters are polygynous. Females often don’t reproduce till two years of age, though yearlings produce offspring once in a while. Males are sexually mature at two years of age. The variety of corpora lutea will increase immediately with age.

North American river otters sometimes breed from December to April. Copulation lasts from 16 to 73 minutes and should happen in water or on land. During the breeding, the male grabs the feminine by the neck along with his teeth.

Copulation is vigorous and is interrupted by intervals of relaxation. Females might caterwaul throughout or shortly after mating. Female estrus lasts a couple of months per year, and true gestation lasts 61–63 days.

Because the North American river otters delay implantation for no less than eight months, the interval between copulation and parturition can attain 10–12 months.

Delayed implantation distinguishes the species from the European otter, which lacks this function. Young are born between February and April and parturition lasts three to eight hours.

In early spring, expectant moms start to search for a den the place they can provide birth. The feminine otters don’t dig their very own dens; as an alternative, they depend on different animals, resembling beavers, to supply appropriate environments to lift their offspring.

When the moms have established their domains, they offer start to a number of kits. Litter size can attain 5, however often ranges from one to a few. Each otter pup weighs roughly 5 ounces.

At birth, the North American river otters are totally furred, blind, and toothless. The claws are well-formed and facial vibrissae (about 5 mm (0.20 in) long) are present.

The kits open their eyes after 30–38 days. The newborns start taking part in at 5 to 6 weeks and start consuming stable meals at 9–10 weeks.

Weaning happens at 12 weeks, and females present stable meals for his or her progeny till 37–38 weeks have transpired. The most weight and size of each sex are attained at three to 4 years of age.

The moms elevate their younger ones without support from adult males. When the pups are about two months old and their coats develop, their mom introduces them to the water. North American river otters are natural swimmers and, with parental supervision, they purchase the skills necessary to swim.

The North American river otters might go away the den by eight weeks and are able to sustain themselves upon the arrival of fall, but they often stick with their households, which generally embody the daddy, till the next spring.

Prior to the arrival of the next litter, the North American river otter yearlings enterprise out in quest of their very own residence ranges.

North American River Otter

North American River Otter Population localization

Aquatic life ties North American river otters nearly completely to everlasting watersheds. The North American river otters favor lavatory lakes with banked shores containing semiaquatic mammal burrows and lakes with beaver lodges.

The North American river otters keep away from water our bodies with step by step sloping shorelines of sand or gravel. In Maine, the use of watersheds by North American river otters is negatively related to the proportion of blended hardwood-softwood stands in forested areas adjoining waterways. However, it’s positively related to the variety of beaver flowages, watershed size, and average shoreline variety.

In Idaho, North American river otters want valley habitats over mountainous terrain, and so they choose valley streams over valley lakes, reservoirs, and ponds. Log jams are closely used when present.

In Florida, the inhabitation of North American river otters is lowest in freshwater marshes, intermediate in salt marshes, and highest in swamp forests. During the dry season, they’ll recede from the marshland and transfer to everlasting ponds, the place water is on the market and meals are in larger provide.

In Idaho and Massachusetts, ecological components most popular for latrine sites embody massive conifers, factors of land, beaver bank dens and lodges, isthmuses, mouths of everlasting streams, or any object that protrudes from the water.

North American River Otter Reproduction

Mating season relies on the latitude wherein the otter was born. However, it sometimes happens in winter or spring. Their gestational interval can final anyplace from two months to at least one year, as otters are able to delayed implantation.

Litter size ranges anyplace from one to 5 pups. They are born blind and stay within the den to nurse for the first month. At about two months they start to enterprise out of the den to play and to learn to swim and hunt.

Otters are recognized for his or her playful nature, whilst adults. Young is in a position to totally look after themselves at about six months of age however they don’t often go away with their mom till about one year.

Males generally type a bunch with different younger males till breeding season; in any other case, a bunch of otters is often feminine along with her younger pups or pups from the earlier litter. Males and females don’t usually affiliate except for its breeding season.


The North American river otter has few natural predators when in water. Aquatic predators embody the American alligator (Alligator mississippiensis), American crocodile (Crocodylus acutus), and killer whale (Orcinus orca), none of which generally coexist with the North American river otter and thus hardly ever pose a risk. On land or ice, the North American river otter is significantly weaker.

Terrestrial predators embody the bobcat (Lynx rufus), mountain lion (Puma concolor), coyote (Canis latrans), home dog (Canis lupus familiaris), wolf (Canis lupus), black bear (Ursus americanus), and (in younger or small North American river otters) red fox (Vulpes vulpes).

Cases the place they have been ambushed and consumed by grizzly bears (Ursus arctos horribilis) and polar bears (Ursus maritimus) have additionally been reportedly witnessed close to the Arctic area.

Most North American river otter mortality is attributable to human-related components, resembling trapping, unlawful taking pictures, roadkills, and unintentional captures in fishnets or set strains. Accidental deaths could also be the result of ice flows or shifting rocks. Starvation might happen because of extreme tooth injury.


Lontra canadensis is listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. They have been just about eradicated by way of many components of their range, particularly round closely populated areas within the midwestern and eastern United States.

The North American river otter is taken into account a species of least concern in response to the IUCN Red List, as it’s not at present declining at a price enough for a risk.

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