River Otter Facts | Top 20 Interesting Facts about North American River Otters

I am going to offer some of the most interesting and rarely known river otter facts and that includes river otter habitat, diet, reproduction, and behavior. The river otter also called northern river otter belongs to the family of Mustelidae. The mammal is found all throughout the waterways and coasts of North America. Common otter is the other name for this animal. It weighs around 5 – 14 kg (11 – 31 lb). Like sea otters, river otters also display thickest furs that ensure a limited heat loss. It is a member of weasel family. It builds its habitat in the swamps, rivers, lakes, tidal flat and coastal shoreline; in the form of burrows. The female litters one to six babies in thes underground burrows. River otters primarily prey on fish, crayfish, turtles and amphibians, and rarely birds.

River Otter Facts

• The weight of a North American river otter measures around 5 – 14 kg (11 – 31 lb). It is recognized by its powerful neck and elongated body. The adult male weighs around 11.3 kg (25 lb); while the female weighs up to 8.3 kg (18 lb).
• River otter reaches a length of about 66 – 107 cm (26 – 42 inches). Around one-third of an otter’s body is composed of a tail. The length of a tail measures around 30 – 50 cm (12 – 20 inches). The larger specimens with the weight of 15 kg (33 lb) are also found.
• River otters have very small eyes and flat head.
• They have 57,800 hairs per square centimeter with the length of the hair measuring at 23.8 mm (0.94 inch).
• Females are 5 per cent smaller as compared to males.
• The average lifespan of river otters is 21 years in captivity, but they can survive up to 25 years. In the wild they live up to 8 – 9 years with the maximum age of 13 years.
• The river otter is perfectly equipped for aquatic life.
• The adult river otter has 36 teeth in total.
• It remains active all throughout the year and become increasingly active at night.
• River otters are nocturnal and they come out in at night in the summer and spring seasons.
• They are not known to migrate each year.
• These otters can walk, slide, bound and even run on land.
• North American otters are capable to travel at a speed of 42 km (26 miles) per day.
• River otter often play games and they chase one another in a game. While playing games, otters also learn some new techniques about fighting and hunting. However, not many species play games.
• River otter swims at a speed of 11 km/h (6.8 mph); and dive at a depth of 20 meters (22 yards). They are known to travel up to 400 meters (440 yards) under water.
• Unlike many mustelids, river otters are more social animals.
• The group is composed of an adult female and her progeny.
• The male river otters are not territorial.
• They primarily communicate through auditory signals.
• They produce a growl-like sound which is often heard while they are in pain.
• The river otter is the best swimmer of the weasel family.
• It can able to stay under water for about 4 minutes.
• River otters are intelligent animals and they often like to play.
• It uses its sight to hunt its prey.

Read More: How Many Sea Otters are Left in the World?

Reproduction | River Otter Facts

• River otters are polygynous. Both male and female becomes mature after two years of age.
• They usually breed in the months of December to April.
• The gestation period lasts for 61 – 63 days.
• The sightless and nearly helpless young are usually born in the months of March and May.
• The river otters do not dig their own den; they use habitats of other animals such as beavers instead.
• The juveniles will wean from their mother’s milk in around 10 – 14 weeks.
• Litter size may compose of 3 – 5 young (1 – 3 being an average). The juveniles are blind and toothless at birth.
• The young will become independent after six months.
• The young will open its eyes after 30 – 38 days and they will start eating solid food after 9 – 10 weeks.

Where Do River Otters Live | River Otter Facts

Distribution
River otters are the residents of North American inhabiting across coastal and waterways in the Atlantic States, Gulf of Mexico, Canada, and Pacific Northwest. Today, a large number of otters are found in the United States and Canada. Some lives in the forested areas of Pacific coast of North America. In Alaska, the Aleutian Islands and Brooks Range hosts many river otters.

Read More: Why are Sea Otters Endangered?

Sadly speaking, pollution and urbanizations have led to the decrease in river otter population. They are beginning to disappear from regions once considered as major habitats such as in New Mexico, Indiana Kansas, Arizona, South Dakota, Oklahoma, West Virginia, and Ohio. However, the largest population of these animals is found in the Great Lakes of North America.

Habitat

River otters are found in diverse habitats ranging from coastal marine waters such as inland wetlands, marshes, lakes, rivers, coastal shorelines to the freshwater streams. They build burrows abandoned by other animals including beavers, muskrats, and woodchucks.

What Do River Otters Eat | River Otter Facts

River otters primarily feed on fish with the size ranges from 2 – 50 cm (0.79 – 20 inches) which is really necessary since fish is a great source for gaining calories. These include game fishes, bass (Centrarchidae) suckers (Catostomidae), and shiners. River otter’s diet also embraces redhorses, cubs, bullheads, catfish, darters, perches, sculpins, pike, salmon, trout, and pike.

The adult river otters are known to eat 1 – 1.5 kg (2.2 0 3.3 lb) of fish each day. Otters living in captivity largely prefer to consume bigger fish with the size of 15 – 17 cm (5.9 – 6.7 inches).

Crustaceans

River otters also consume crustaceans such as crayfish since crayfish is relatively abundant species and is available all year round. Crayfish makes up one-third of the otters diet.

Reptiles and Amphibians | River Otter Facts

In the summer and spring seasons, river otters fancy eating amphibians including boreal chorus frogs, Canadian toads, wood frogs, bullfrogs, green frogs, rough-skinned newt, garter snakes, and Pacific giant salamander.

Birds

In certain areas, river otters rely on birds for their consumption and these birds include green-winged, teal, mallard, ruddy ducks, American coot, American wigeon, waterfowls, rails, and northern pintail. However, otters never eat bird eggs.

Insects

The primary foods for otters are aquatic invertebrates and aquatic insects. Adult beetles and stonefly nymphs are just a few of these.

Mammals

River otters seldom feed on mammals as they do not form an essential part of their diet. Mammals include eastern cottontails, snowshoe hares, and meadow voles.