The North American river otter (''Lontra canadensis''), also known as the northern river otter and river otter, is a

semiaquatic In biology, semiaquatic can refer to various types of animals that spend part of their time in water, or plants that naturally grow partially submerged in water. Examples are given below. Semiaquatic animals Semi aquatic animals include: * Ve ...

mammal that only lives on the

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

continent, along its waterways and coasts. An adult North American river otter can weigh between . The river otter is protected and insulated by a thick, water-repellent coat of fur. The North American river otter, a member of the subfamily Lutrinae in the

weasel family The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in the ...

(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. North American river otters, like most predators, prey upon the most readily accessible species.

Fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

is a favored food among the otters, but they also consume various amphibians (such as

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

s and

frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...

s), freshwater clams, mussels,

snails A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...

, small

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

s and crayfish. The most common fish consumed are perch, suckers, and catfish. Occasional reports also show the river otter eating other small animals, such as mice, squirrels, birds, and even dogs that they've attacked and drowned. The range of the North American river otter has been significantly reduced by habitat loss, beginning with the

European colonization of the Americas During the Age of Discovery, a large scale European colonization of the Americas took place between about 1492 and 1800. Although the Norse had explored and colonized areas of the North Atlantic, colonizing Greenland and creating a short t ...

. In some regions, though, their population is controlled to allow the trapping and harvesting of otters for their

fur Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket t ...

. North American river otters are very susceptible to the effects of

environmental pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, th ...

, 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.

Taxonomy and evolution

The North American river otter was first described by German naturalist Johann Christian Daniel von Schreber in 1777. 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. Other documented common names are American otter, Canada otter, Canadian otter, fish otter, land otter, nearctic river otter, and Prince of Wales otter. The North American river otter was first classified in the genus ''

Lutra ''Lutra'' is a genus of otters, one of seven in the subfamily Lutrinae. Taxonomy and evolution The genus includes these species: Extant species Extinct species *†'' Lutra affinis'' *†'' Lutra bressana '' *†'' Lutra bravardi'' *†'' ...

''. ''Lutra'' was the early European name (from Latin), and the specific epithet ''canadensis'' means "of Canada". In a new classification, the species is called ''Lontra canadensis'', where the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Lontra ''Lontra'' is a genus of otters from the Americas. Species These species were previously included in the genus ''Lutra'', together with the Eurasian otter The Eurasian otter (''Lutra lutra''), also known as the European otter, Eurasian river ...

'' includes all the

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...

river otters. Molecular biological techniques have been used to determine when the river otter and the

giant otter The giant otter or giant river otter (''Pteronura brasiliensis'') is a South American carnivorous mammal. It is the longest member of the weasel family, Mustelidae, a globally successful group of predators, reaching up to . Atypical of muste ...

(''Pteronura brasiliensis'') of South America diverged. These analyses suggest they diverged in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

epoch 23.03 to 5.33 million years ago (Mya), which is "much earlier" than indicated in the fossil record. Fossils of a giant river otter dating back 3.5 Mya (during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 The

river otters originated from the Old World river otters following a migration across the

Bering Land Bridge Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72 degrees north latitude in the Chukchi Sea; and on the south by the tip of ...

, which existed off and on between 1.8 million and 10,000 years ago. This means they likely arrived in the Americas at a similar time as humans, meaning humans were an important part of their natural ecosystem from the moment otters arrived. The otters migrated to North America and southwards again across the Panamanian Land Bridge, which formed 3 Mya.

Subspecies

Listed alphabetically: *''L. c. canadensis'' (Schreber, 1777) – (eastern Canada, U.S., Newfoundland) *''L. c. kodiacensis'' (Goldman, 1935) – (

Kodiak Island Kodiak Island ( Alutiiq: ''Qikertaq''), is a large island on the south coast of the U.S. state of Alaska, separated from the Alaska mainland by the Shelikof Strait. The largest island in the Kodiak Archipelago, Kodiak Island is the second la ...

, 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 California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, northern

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

, and northeastern

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

) *''L. c. periclyzomae'' (Elliot, 1905) – (

Queen Charlotte Islands Haida Gwaii (; hai, X̱aaydag̱a Gwaay.yaay / , literally "Islands of the Haida people") is an archipelago located between off the northern Pacific coast of Canada. The islands are separated from the mainland to the east by the shallow Heca ...

, British Columbia) *''L. c. sonora'' (Rhoads, 1898) – (U.S.,

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

)

Description

The North American river otter has long whiskers that are used to detect prey in dark waters. An average adult male weighs about against the female's average of . Its body length ranges from . About one-third of the animal's total length consists of a long, tapered tail. Tail lengths range from . Large male North American river otters can exceed a weight of . It differs from the

European otter The Eurasian otter (''Lutra lutra''), also known as the European otter, Eurasian river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia. The most widely distributed member of the otter subfamily (Lutrinae) of th ...

by its longer neck, narrower visage, the smaller space between the ears and its shorter tail. Its whiskers ( vibrissae) are long and thick, enhancing their senses. Males and female river otters show different non-sexual physical characteristics, with males typically being larger. North American river otters can live 21–25 years in captivity, or 8–13 years in the wild.

Form and function

North American river otters characteristically approach within a few feet of a boat or a person on shore because they're near-sighted, a consequence of vision adapted for underwater sight. North American river otters have transparent nictitating membranes to protect their eyes while swimming. Most mustelids, including otters, have 36 specialized teeth, including sharp

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

and

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

s that inflict lethal bites to prey. Also, North American river otters have large

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

used for crushing hard objects, such as the shells of molluscs. Additional premolars may be present. The

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolog ...

is .

North American River Otter - CNP 3361 (7056954311)

Behavior

North American river otters only settle in areas that consist of vegetation, rock piles, and sufficient coverage.

Movement

Playing

North American river otters are renowned for their sense of play. Otter play mostly consists of wrestling with conspecifics. Chasing is also a common game. North American river otters rely upon play to learn survival skills such as fighting and hunting.

Hunting

A highly active predator, the North American river otter has adapted to hunting in water, and eats aquatic and semiaquatic animals. The vulnerability and seasonal availability of prey animals mainly governs its food habits and prey choices. This availability is influenced by the following factors: detectability and mobility of the prey, habitat availability for the various prey species, environmental factors, such as water depth and temperature, and seasonal changes in prey supply and distribution in correspondence with otter foraging habitat. The diet of the North American river otter can be deduced by analyzing either stool obtained in the field, or gut contents removed from trapped otters. Fish are the primary component of the North American river otter's diet throughout the year. Every study done on the food habits of the North American river otter has identified varying fish species as being the primary component of its diet. For instance, an Alberta, Canada study involved the collection and analysis of 1,191 samples of North American river otter scat (feces) collected during each season. Fish remnants were found in 91.9% of the samples. Moreover, a western Oregon study revealed fish remains were present in 80% of the 103 digestive tracts examined.

Crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s ( crayfish), where regionally available, are the second-most important prey for otters. Crustaceans may even be consumed more than fish. For example, a study conducted in a central California marshland indicated crayfish formed nearly 100% of the river otter's diet at certain times of the year. However, North American river otters, as foragers, will immediately take advantage of other prey when readily obtainable. Other prey consumed by North American river otters includes

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

s, reptiles, amphibians,

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s (most especially moulting

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form ...

s which render the birds flightless and thus makes them easier to capture), aquatic

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

s, small mammals, and

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s. North American river otters are not scavengers; they avoid consuming carrion (dead animals).Hansen, H. (2003)
Food habits of the North American river otter (''Lontra canadensis'')
University of Wyoming. North American river otters do not generally handle prey of a large size relative to themselves but there are occasions where they've been observed ambushing and killing adult common snapping turtles while the large turtles (which are roughly equal in average body weight to a North American river otter) are hibernating. Remains of the much larger

North American beaver The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America ( Patagonia) and Europe (primarily Finland ...

have been found in North American river otter scat in some regions, although most otter dietary studies in areas where otters and beaver live near each other do not show them to be regular predators of beavers (despite the claims of fur-trappers that otters frequently hunt beavers) and perhaps only young beaver kits may be attacked.

Ecological impacts on prey species

When left unchecked, though, otters can be significant predators under certain circumstances (e.g. in

hatcheries A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish, poultry or even turtles. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled condi ...

or other fish culture facilities). Likewise, the potential predatory impact of otters may be considerable whenever fish are physically confined (most commonly in smaller ponds offering sparse cover or other escape options). To protect fish in these cases, the otters may need to be removed or relocated. Even in larger bodies of water, river otters may take disproportional advantage of any seasonal concentrations of fish when and where only very limited areas of suitable spawning, low-flow, or over-wintering habitat may exist. Even fast-swimming fish like trout slow down in extremely cold water, leaving them vulnerable. As such, careful consideration of any threatened, endangered, or fish species of special interest is warranted prior to reintroduction of otters to a watershed.

Social behavior

Male North American river otters disperse from such family groups more often than females. When females leave, they tend to move much further away () than males (up to ), which tend to move shorter distances. Male North American river otters do not seem to be territorial, and newly dispersing males may join established male groups.

Reproduction and life cycle

Delayed implantation distinguishes the species from the European otter, which does not do this. In early spring, expectant mothers begin to look for a den where they can give birth. The female otters do not dig their own dens; instead, they rely on other animals, such as beavers, to provide suitable environments to raise their offspring. When the mothers have established their domains, they give birth to several kits. Litter size can reach five, but usually ranges from one to three. Each otter pup weighs approximately five ounces. The mothers raise their young without aid from adult males. When the pups are about two months old and their coats grow in, their mother introduces them to the water. North American river otters are natural swimmers and, with parental supervision, they acquire the skills necessary to swim. The North American river otters may leave the den by eight weeks and are capable of sustaining themselves upon the arrival of fall, but they usually stay with their families, which sometimes include the father, until the following spring. Prior to the arrival of the next litter, the North American river otter yearlings venture out in search of their own home ranges.

Geographic range

The North American river otter is found throughout North America, inhabiting inland waterways and coastal areas in Canada, the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Tho ...

, the Atlantic states, and the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

. North American river otters also currently inhabit coastal regions throughout the United States and Canada. North American river otters also inhabit the forested regions of the Pacific coast in North America. The species is also present throughout Alaska, including the

Aleutian Islands The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large v ...

, and the north slope of the

Brooks Range The Brooks Range ( Gwich'in: ''Gwazhał'') is a mountain range in far northern North America stretching some from west to east across northern Alaska into Canada's Yukon Territory. Reaching a peak elevation of on Mount Isto, the range is belie ...

. However, urbanization and pollution instigated reductions in range area. They are now absent or rare in Arizona, Kansas, Nebraska, New Mexico, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, and West Virginia. Reintroduction projects have expanded their distribution in recent years, especially in the

Midwestern United States The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. I ...

. Since their reintroduction to Kentucky in the early 90s, they have recovered to the point that a trapping season was started in 2006, and the species is now found in all major waterways. In 2010, the Colorado Department of Wildlife reported the species, reintroduced in the 1980s, was "thriving" and recommended its protection status be reconsidered. In late 2012, a river otter nicknamed Sutro Sam took up residence around the former site of the

Sutro Baths The Sutro Baths was a large, privately owned public saltwater swimming pool complex in the Lands End area of the Outer Richmond District in western San Francisco, California. Built in 1894, the Sutro Baths was located north of Ocean Beach, ...

San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...

, the first river otter sighting in that city in more than half a century. In Canada, North American river otters occupy all provinces and territories, except until recently

Prince Edward Island Prince Edward Island (PEI; ) is one of the thirteen provinces and territories of Canada. It is the smallest province in terms of land area and population, but the most densely populated. The island has several nicknames: "Garden of the Gulf", ...

. Otters have recently re-established themselves on Prince Edward Island. Historical records indicate North American river otters were once populous throughout most major drainages in the continental United States and Canada prior to European settlement. North America's largest North American river otter populations were found in areas with an abundance and diversity of aquatic habitats, such as coastal marshes, the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lak ...

region, and

glaciated A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

areas of

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the Can ...

. In addition, riverine habitats in interior regions supported smaller, but practical, otter populations. The North American river otter existed on all parts of the Pacific Coast, including the seashore and inland streams and lakes. However, large populations never occurred in areas of

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

such as the chaparral and oak woodlands and

Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...

seasonal waterway regions, or in the

xeric shrubland Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this ...

regions in New Mexico, Texas, Nevada, and Colorado. In Mexico, the North American river otters lived in the Rio Grande and

Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...

Habitat

River_otter_on_bank,_Park_Ave_San_Anselmo_Creek_Charles_Kennard_cropped

Although commonly called a "river otter", the North American river otter is found in a wide variety of aquatic habitats, both freshwater and coastal marine, including 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 main requirements are a steady food supply and easy access to a body of water. However, it is sensitive to pollution, and will disappear from tainted areas. Like other otters, the North American river otter lives in a holt, or den, constructed in the burrows of other animals, or in natural hollows, such as under a log or in river banks. An entrance, which may be under water or above ground, leads to a nest chamber lined with leaves, grass, moss, bark, and hair. River otter Richmond Marina Scott Campbell July 29, 2010

River otter Richmond Marina Scott Campbell July 29, 2010

Population localization

Aquatic life ties North American river otters almost exclusively to permanent watersheds.

Diet

Fish

North American river otters consume an extensive assortment of fish species ranging in size from that impart sufficient caloric intake for a minute amount of energy expenditure. North American river otters generally feed on prey that is in larger supply and easier to catch. As a result, slow-swimming fish are consumed more often than

game fish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commercial ...

es when both are equally available. Slow-moving species include suckers (

Catostomidae The Catostomidae are the suckers of the order Cypriniformes, with about 78 species in this family of freshwater fishes. The Catostomidae are almost exclusively native to North America. The only exceptions are '' Catostomus catostomus,'' found in ...

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...

, sunfish and bass (

Centrarchidae Centrarchidae, better known as sunfishes, is a family of freshwater ray-finned fish belonging to the order Perciformes (formerly belonging to the deprecated order Centrarchiformes), native only to North America. There are eight universally i ...

), daces, carp, and shiners (

Cyprinid Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest ver ...

ae). For instance, Catostomidae are the primary dietary component of North American river otters in Colorado's Upper Colorado River Basin. Likewise, the common carp (''Cyprinus carpio'') is a preferred fish species for the North American river otter in other regions of Colorado. Fish species frequently found in the diets of the North American river otters include: Catostomidae, which consists of suckers (''

Catostomus ''Catostomus'' is a genus of fish belonging to the family Catostomidae, commonly known as suckers. Most members of the genus are native to North America, but '' C. catostomus'' is also found in Russia. Fish from different species of the genus ar ...

'' spp.) and

redhorse ''Moxostoma'', the redhorses or jumprocks, is a genus of North American ray-finned fish in the family Catostomidae. Species * '' Moxostoma albidum'' ( Girard, 1856) (Longlip jumprock) * ''Moxostoma anisurum'' ( Rafinesque, 1820) (Silver redho ...

s (''Moxostoma'' spp.); Cyprinidae, made up of carp (''Cyprinus'' spp.),

chubs Chub is a common fish name. It pertains to any one of a number of ray-finned fish in several families and genera. In the UK, the term ''chub'' usually refers to the species ''Squalius cephalus''. In addition, see sea chub. In family Cyprinidae ...

(''Semotilus'' spp.), daces (''Rhinichthys'' spp.), shiners (''Notropis'' and ''Richardsonius'' spp.), and squawfishes (''

Ptychocheilus Pikeminnows, formerly squawfish, are cyprinid fish of the genus ''Ptychocheilus'' consisting of four species native to western North America. Voracious predators, they are considered an "undesirable" species in many waters, largely due to the spe ...

'' spp.); and Ictaluridae, which consists of bullheads and

(''Ictalurus'' spp.). Other fish an integral part of the North American river otters' diets are those that are often plentiful and found in large schools: sunfish (''Lepomis'' spp.); darters (''Etheostoma'' spp.); and

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Per ...

es (''Perca'' spp.). Bottom-dwelling species, which have the tendency to remain immobile until a predator is very close, are susceptible to North American river otters. These include mudminnows (''Umbra limi'') and sculpins (''Cottus'' spp.). Game fish, such as

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...

(Salmonidae) and

pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...

(Esocidae), are not a significant component of their diets. They are less likely to be prey for the North American river otters since they are fast-swimming and can find good escape cover. However, river otters will prey on trout, pike,

walleye The walleye (''Sander vitreus'', synonym ''Stizostedion vitreum''), also called the yellow pike or yellow pickerel, is a freshwater perciform fish native to most of Canada and to the Northern United States. It is a North American close relat ...

(''Sander vitreus vitreus''),

salmon Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus ''Salmo'') and North Pacific (genus '' Oncorhy ...

(''Oncorhynchus'' spp.), and other game fish during

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

. Otters have been found to consume invasive Asian carp. Adult North American river otters are capable of consuming of fish per day. A study conducted on captive otters revealed they preferred larger fish, ranging from , more than smaller fish, ranging from , and they had difficulty catching fish species less than or larger than . Otters are known to take larger fish on land to eat, whereas smaller fish are consumed in the water.

Crustaceans

North American river otters may prefer to feed on

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s, especially crayfish ('' Cambarus'', '' Pacifasticus'', and others) and

crabs Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

more than fish where they are locally and seasonally plentiful. In Georgia, crayfish accounted for two-thirds of the prey in the summer diet, and their remnants were present in 98% of the summer

spraint Spraint is the dung of the otter. Spraints are typically identified by smell and are known for their distinct odors, the smell of which has been described as ranging from freshly mown hay to putrefied fish. The Eurasian otter The Eurasian ott ...

. In the winter, crayfish made up one-third of the North American river otter's diet. A study conducted on North American river otters in a southwestern Arkansas swamp identified a correlation between crayfish consumption, fish consumption, and water levels. During the winter and spring, when the water levels were higher, North American river otters had a greater tendency to prey upon crayfish (73% of scats had crayfish remains) rather than fish. However, when water levels are lower, crayfish will seek out shelter while fish become more highly concentrated and susceptible to predation. Therefore, fish are more vulnerable to being preyed upon by otters because the crayfish have become more difficult to obtain.

Reptiles and amphibians

Amphibians, where regionally accessible, have been found in the North American river otter's diet during the spring and summer months, as indicated in many of the food habit studies. The most common amphibians recognized were

s (''Rana'' and ''Hyla''). Specific species of reptiles and amphibians prey include: boreal chorus frogs (''Pseudacris maculata''); Canadian toads (''Bufo hemiophrys'');

wood frog ''Lithobates sylvaticus'' or ''Rana sylvatica'', commonly known as the wood frog, is a frog species that has a broad distribution over North America, extending from the boreal forest of the north to the southern Appalachians, with several nota ...

s (''Rana sylvatica'');

bullfrog ''Bullfrog'' is a common English language term to refer to large, aggressive frogs, regardless of species. Examples of bullfrogs include: Frog species America * Helmeted water toad (''Calyptocephalella gayi''), endemic to Chile *American bullfr ...

s (''Rana catesbeiana''); green frogs (''Rana clamitans''); northwestern salamanders (''Ambystoma gracile''); California giant salamander (''Dicamptodon ensatus'');

rough-skinned newt The rough-skinned newt or roughskin newt (''Taricha granulosa'') is a North American newt known for the strong toxin exuded from its skin. Appearance A stocky newt with rounded snout, it ranges from light brown to olive or brownish-black on ...

(''Taricha granulosa''); and

garter snake Garter snake is a common name for generally harmless, small to medium-sized snakes belonging to the genus ''Thamnophis'' in the family Colubridae. Native to North and Central America, species in the genus ''Thamnophis'' can be found from the ...

s (''Thamnophis''). Amphibians and reptiles are more obtainable by the North American river otter during the spring and summer as a result of breeding activity, appropriate temperatures, and water supply for the prey.

Birds

Waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

rails Rail or rails may refer to: Rail transport *Rail transport and related matters *Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ( ...

, and some colonial nesting birds are preyed upon by North American river otters in various areas. Susceptibility of these species is greatest during the summer (when waterfowl broods are vulnerable) and autumn. The North American river otters have also been known to catch and consume moulting

American wigeon The American wigeon (''Mareca americana''), also known as the baldpate, is a species of dabbling duck found in North America. Formerly assigned to ''Anas'', this species is classified with the other wigeons in the dabbling duck genus '' Mareca'' ...

(''Mareca americana'') and

green-winged teal The green-winged teal (''Anas carolinensis'') is a common and widespread duck that breeds in the northern areas of North America except on the Aleutian Islands. It was considered conspecific with the Eurasian teal (''A. crecca'') for some time, ...

(''Anas crecca''). Other species of birds found within their diets include:

northern pintail The pintail or northern pintail (''Anas acuta'') is a duck species with wide geographic distribution that breeds in the northern areas of Europe and across the Palearctic and North America. It is migratory and winters south of its breeding ...

(''Anas acuta''); mallard (''Anas platyrhynchos'');

canvasback The canvasback (''Aythya valisineria'') is a species of diving duck, the largest found in North America. Taxonomy Scottish-American naturalist Alexander Wilson described the canvasback in 1814. The genus name is derived from Greek ''aithuia'', ...

(''Aythya valisineria'');

ruddy duck The ruddy duck (''Oxyura jamaicensis'') is a duck from North America and one of the stiff-tailed ducks. The genus name is derived from Ancient Greek ''oxus'', "sharp", and ''oura'', "tail", and ''jamaicensis'' is "from Jamaica". Taxonomy The r ...

(''Oxyura jamaicensis''); and the

American coot The American coot (''Fulica americana''), also known as a mud hen or pouldeau, is a bird of the family Rallidae. Though commonly mistaken for ducks, American coots are only distantly related to ducks, belonging to a separate order. Unlike the w ...

(''Fulica americana''). Although they consume birds, North American river otters do not feed on bird eggs.

Insects

Aquatic invertebrates have been recognized as an integral part of the North American river otter's diet. Otters consume more aquatic insects in the summer as the populations increase and specific life stages heighten their susceptibility. Most aquatic invertebrates preyed upon by the otters are from the families Odonata (

dragonfly nymph A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threate ...

s), Plecoptera ( stonefly nymphs), and Coleoptera ( adult beetles). Invertebrates discovered within scats or digestive tracts could most likely be a secondary food item, first being consumed by the fish that are subsequently preyed upon by the North American river otters.

Mammals

Mammals are rarely consumed by North American river otters, and are not a major dietary component. Mammals preyed upon by North American river otters are characteristically small or are a type species found in

riparian zones A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...

. The few occurrences of mammals found in the North American river otter's diet include: muskrats (''Ondatra zibethicus'');

meadow vole The eastern meadow vole (''Microtus pennsylvanicus''), sometimes called the field mouse or meadow mouse, is a North American vole found in eastern Canada and the United States. Its range extends farther south along the Atlantic coast. The west ...

s (''Microtus pennsylvanicus'');

eastern cottontail The eastern cottontail (''Sylvilagus floridanus'') is a New World cottontail rabbit, a member of the family Leporidae. It is the most common rabbit species in North America. Distribution The eastern cottontail can be found in meadows and shrubb ...

s (''Sylvilagus floridanus''); and

snowshoe hare The snowshoe hare (''Lepus americanus''), also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sin ...

s (''Lepus americanus''). Records of North American otters preying upon North American beavers (''Castor canadensis'') vary; it has been reported in the southern boreal forest of Manitoba. Trappers in Alberta, Canada commonly assert North American river otters are major predators of North American beavers. A 1994 river otter study reported findings of beaver remains in 27 of 1,191 scats analyzed. However, many other studies did not report any findings of North American beaver remains in the scat sampled.

Threats

Cases where otters have been ambushed and consumed by grizzly bears (''Ursus arctos horribilis'') and polar bears (''Ursus maritimus'') have also been reportedly witnessed near the Arctic region.. Threats to North American river otter populations in North America vary regionally. North American river otter inhabitation is affected by type, distribution, and density of aquatic habitats and characteristics of human activities. Preceding the settlement of North America by Europeans, North American river otters were prevalent among aquatic habitats throughout most of the continent. Trapping, loss or degradation of aquatic habitats through filling of wetlands, and development of coal, oil, gas, tanning, timber, and other industries, resulted in local extinctions or population declines in North American river otter populations in many areas. In 1980, an examination conducted on U.S. river otter populations determined they were locally extinct in 11 states, and lost significant population in 9 other states. The most severe population declines occurred in interior regions where fewer aquatic habitats supported fewer otter populations. Although the distribution became reduced in some regions of southern Canada, the only province-wide extinction occurred on

. During the 1970s, improvements in natural resource management techniques emerged, along with increased concerns about North American river otter population declines in North America. Consequently, many wildlife management agencies developed strategies to restore or enhance otter populations, including the use of reintroduction projects. Since 1976, over 4,000 otters have been reintroduced in 21 U.S. states. All Canadian provinces except Prince Edward Island and 29 U.S. states have viable populations that sustain annual harvests. While current harvest strategies do not pose a threat to maintaining otter populations, harvest may limit expansion of otter populations in some areas. Oil spills present a localized threat to otter populations, especially in coastal areas. Water pollution and other diminution of aquatic and wetland habitats may limit distribution and pose long-term threats if the enforcement of water quality standards is not upheld. Acid drainage from

coal mines Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron fro ...

is a persistent water quality issue in some areas, as it eliminates otter prey. This dilemma prevents, and consequently inhibits, recolonization or growth of North American river otter populations. Recently, long-term genetic consequences of reintroduction projects on remnant North American river otter populations has been discussed. Similarly, many perceived threats to North American river otters, such as pollution and habitat alterations, have not been rigorously evaluated. Little effort has gone into assessing the threat of disease to wild North American river otter populations, so it is poorly understood and documented.

Conservation status

Curious Otter at Lake Woodruff National Wildlife Refuge - Flickr - Andrea Westmoreland

''Lontra canadensis'' is listed in Appendix II of the

Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of intern ...

(CITES). They have been virtually eliminated through many parts of their range, especially around heavily populated areas in the midwestern and eastern United States. Appendix II lists species that are not necessarily threatened with extinction currently, but may become so unless trade is closely controlled. The North American river otter is considered a species of

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

according to the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

, as it is not currently declining at a rate sufficient for a threat category. By the early 1900s, North American river otter populations had declined throughout large portions of their historic range in North America. However, improvements in water quality (through enactment of clean water regulations) and furbearer management techniques have permitted river otters to regain portions of their range in many areas. Reintroduction projects have been particularly valuable in restoring populations in many areas of the United States. However, North American river otters remain rare or absent in the southwestern United States. Water quality and development inhibit recovery of populations in some areas. The species is widely distributed throughout its range. In many places, the populations have re-established themselves because of conservation initiatives. Reintroduction of river otters may present a problem in that it may contaminate the genetic structure of the native population.

References

External links

* * {{Taxonbar, from=Q327028

North American river otter The North American river otter (''Lontra canadensis''), also known as the northern river otter and river otter, is a semiaquatic mammal that only lives on the North American continent, along its waterways and coasts. An adult North American rive ...

Carnivorans of North America Mammals of North America Mammals of Canada Mammals of the United States Mammals of Mexico Fauna of the Rocky Mountains Fauna of the Sierra Nevada (United States) Fauna of the San Francisco Bay Area Least concern biota of North America Least concern biota of the United States

Semiaquatic animals Fur trade