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River Otter in South Dakota

South Dakota's tumbling prairie lands contain hidden treasures. Treasures, such as rivers and streams, cut through rough terrain forming unique water systems and extraordinary riparian areas (water edge plants). These prairie rivers support a diversity of aquatic animals. At one time, a playful semi-aquatic animal survived in South Dakota's prairie rivers - the vigorous and active river otter (Lontra canadensis). Extensive trapping pressure, habitat loss or degradation, and urban development forced river otter populations near the point of extinction with the expansion of Europeans into the New World nearly 100 years ago. Since this population decline, river otters have not been able to re-establish in South Dakota.

The river otter and the mink are close relatives, although specific physical characteristics and behavioral habits differ. River otters are about twice the size of a mink, weighing from 15 to 25 lbs (7 to 11 kg). Besides being larger, river otters lack a white chin patch, which is characteristic of minks. A sleek design, such as a long tail and slender body, allows river otters to swim fast and maneuver around many obstacles. The plush, brown fur is waterproof, protecting the river otter from extreme environmental conditions.

River otters share similar foods and locales as a mink. Food and habitat are limiting resources for river otters, which means river otters require ample food and adequate cover to survive. River otters dive in rivers, streams, or lakes primarily feeding on aquatic organisms. River otters are proficient hunters fiercely challenging prey. Fish are the river otter's favorite cuisine, but they also will gulp down amphibians and crustaceans. Since amphibians and crustaceans supplement the diet, these foods are more of a delicacy. Fish eaten by river otters include catfish, bullheads, suckers, carp, and sunfish. Amphibians that river otters eat include frogs or toads, while crustaceans include crayfish or mussels. Once feeding is complete, river otters will rest or sleep in proper den areas, which are usually in riparian zones.

River otters are lazy engineers that use abandoned or active structures created by other animals as den-sites (e.g., beavers). Shoreline foliage and debris, such as grass, fallen trees, or abandoned beaver lodges, are typical sources of cover and den-sites. Den-sites are primarily used for resting and relaxing. Females rely more heavily on den-sites with the arrival of two to three pups in March or April. Once young of the year are born, family groups of three to four river otters can be seen sliding on banks and frolicking in the water. River otters are excellent swimmers, although the majority of their time is spent on land or in dens. Because of their effortless land and water usage, river otters are sometimes called "land otters". Not many animals are able to fluently survive on land and water.

One notable characteristic of river otters is their social habit. Playing and swimming in streams, rivers, lakes, and ponds is common for river otters. Play includes games, such as tag and catch, and leisurely swims. River otter slides can be seen along riverbanks and in the snow. The easily observed slides measure approximately 10 ft (3.0 m) long and 1 ft (0.27 m) wide. River otters are one of the few animals that play as adults.

Throughout the United States and Canada, river otters were found sliding down riverbanks, lounging around in den-sites, or floating on their back while gobbling a fish. But, like here in South Dakota, river otter populations in some other states were diminished. Recent concern to return (restore) river otters to waters where they once resided has developed throughout the central portions of the United States. Restoration programs were initiated to determine whether river otters could be restored or reintroduced into their natural range. States with active restoration programs include Louisiana, Missouri, Iowa, Kansas, Wisconsin, Illinois, Indiana, Ohio, Colorado, Oklahoma, Arizona, California, Florida, West Virginia, Kentucky, New York, Tennessee, Pennsylvania, Nebraska, and Minnesota.

In South Dakota, river otters are considered a threatened species. With low numbers, river otters cannot be trapped or hunted. Efforts have been taken to determine habitat available to river otters, and as a result several rivers were identified as areas potentially suitable for river otters: the Big Sioux River, Bad River, Little White River, North Fork of the Whetstone River, and James River. At this time, the Department of Game, Fish and Parks does not plan to restore river otters in South Dakota--further internal communications and public relations is needed--though restoration efforts have been conducted by the Flandreau Santee Sioux Tribe in eastern South Dakota. The presence of river otters offers aesthetic, cultural, and ecological aspects or values to people and the environment, and the opportunity to return this charming and amazing mammal, the river otter, to its native waters is exhilarating.

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Big Sioux River

This river is an exampleof typical river otter habitat found in South Dakota.
(Photo: Alyssa Kiesow)

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River Otter Scat
This is typical river otter scat - usually found on mounds of vegetation or near travel routes. Note: quarter is for size reference.
(Photo: Jacquie Ermer)

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Bank Den
This is another example of a river otter den site.
(Photo: Jason Jungwirth)

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River Otter Footprint
This is a typical river otter track. Note: quarter is for size reference.
(Photo: Alyssa Kiesow)

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Beaver Lodge
This is one type of river otter den site.
(Photo: Jason Jungwirth)