The arrival this summer of two North American rivers otters (Lontra canadensis) to the North Carolina Zoo marked the return of one of zoo visitors’ favorite animals. The two, a 7-year-old female and a 3-year-old male, arrived in May.

The river otter, also known as the northern river otter or the common otter, is a semi-aquatic mammal – both land-dwelling and water-dwelling. As their name implies, otters are found throughout Canada and the United States – except for areas of southernmost California, New Mexico and Texas, and the Mohave Desert area of Nevada and Colorado. In Mexico, they can be found in the delta areas of the Rio Grande and Colorado rivers.

According to the U.S. Forest Service, otter populations in the wild are considered reasonably secure overall. Severe declines in otter populations in many parts of the United States began in the 1800’s due to unregulated fur harvest and habitat destruction. During that time, otter populations were destroyed completely in some states and nearly destroyed or severely reduced in others.

But today, trapping regulations, improved water quality and species management have re-established the species to much of its former range in North America.

River otters are found in a variety of environments due to insulation in their thick, water-repellent fur, which allows them to tolerate cold and warmer latitudes and high elevations. Generally, they’re found wherever there is easy access to water and a permanent food supply.

In the winter, they remain active in water and use ice holes to surface and breathe. They can hold their breath underwater for as long as five to eight minutes.

Members of the weasel family, they are equally versatile in the water and on land. They dig burrows close to the water’s edge, with multiple tunnel openings that generally allow them to easily enter and exit the water. Females give birth in these burrows and typically produce litters of one to six young.

North American river otters seem to be sensitive to pollution and disappear from areas with polluted waters. They’re considered an indicator species, that is, a species that defines traits or conditions of an environment such as pollution, disease, competition to a particular species or even climate change. Indicator species can be among the most sensitive species in a region and sometimes act as an early warning to biologists who might be studying a certain ecosystem.

As might be expected, otters are physically well-equipped for life in and around the water and built for swimming. Their legs are short and powerful, their toes are fully webbed, the tail – used for propulsion in the water – is one-third of their body length, and nostrils and ears close when otters are underwater. Also, flaps over their eyes act as goggles.

Although these physical characteristics reduce their agility on land, they give them a streamlined profile in water. Otters’ senses of smell and hearing are acute, and they have great dexterity and paws with a delicate sense of touch.

Like most other carnivore mustelids – otters, ferrets, mink, badgers and weasels – otters have specialized teeth, including sharp canines that can inflict lethal bites to their prey. Their large molars allow them to open hard shells, such as those of mollusks and other shellfish, a staple of their diet. Other dietary staples in the wild include fish, frogs, crayfish, other invertebrates and small mammals.

Otters can dive to depths of 60 feet. They’re generally about 30 to 40 inches long as adults, but the largest and most powerful of their 13 species is the giant otter of South America, which sometimes reaches a length of almost six feet.

The smallest is the Oriental (Asian) small-clawed otter, normally less than three feet long.



Tom Gillespie lives in Trinity and is a journalist and public affairs specialist at the North Carolina Zoo. For more information on the zoo’s plant and animal collections, special events and education programs, go to their Web site at www.nczoo.org