Two river otters


Otter exhibit in
the Swamp


Order: Carnivora
Family: Mustelidae

What do North American river otters look like?

North American river otters are rich brown on top, with a silvery sheen on the bottom. They have webbed feet and a tail that is thick at the base and tapers to the tip. River otters have a long neck, short legs, a flat head, strong claws, whiskers, and no hair on their nose. They have a layer of fat under their skin and dense, oily fur that protects them from cold. Males are slightly larger than females, with a head and body up to 66-127 cm long. Their tail can grow up to 43 cm. They can weigh between 4.5 and 11 kg.

How do North American river otters move?

North American river otters can move on land and in water. They are found mostly in the water. They have a streamlined body, and their eyes and ears close under water. When North American river otters are on land, they walk on all four legs.

How do North American river otters communicate?

North American river otters communicate by chirping, chattering, and chuckling. They have a hair-raising scream they use when frightened. It can be heard 2 km away.

Where can North American river otters be found in the world?

They are found all over most of North America, except for the arid west and extreme northern Canada. In the wild, they can be found in streams, along lake borders, and in salt marshes. At Brookfield Zoo, you can find them in The Swamp.

What kind of social behavior can I see?

A pair of otters are together only a short time during breeding season. Otters are best known for the amount of time they play. They like to chase, wrestle, dive for rocks and clamshells, capture and release live prey, and slide on things. Some scientists believe that this play provides young otters with experience and strengthens and sharpens their reflexes. Otters usually have a home range of 25 km or so, but they may wander for 90 km or more.

What about breeding?

Male and female otters are ready for reproduction at about two years of age. A female otter is pregnant for 10 to 12 months, with a litter of one to six. After mating, these otters can exhibit “delayed implantation.” The fertilized egg can remain in the uterus for up to nine months. Once the egg is implanted in the uterine wall, its development continues for 60 days.

How are young raised?

Young otters are helpless at birth and do not open their eyes until they are three weeks old. When they are about 60 days old, they leave the den and are introduced to the water. The female cares for the young otters and teaches them to swim, catch prey, and look for food. Young otters can care for themselves in about five to six months, but the family often stays together until the birth of a new litter.

What do North American river otters eat?

River otters eat fish, crustaceans, insects, birds, muskrats, and clams.

What is North American river otters’ status in the wild?

North American river otters are endangered in some states, and are threatened in Illinois. They are abundant in Canada, Alaska, and the Pacific Northwest. Pollution and pesticides cause serious problems for river otters. Their habitats are being destroyed by humans. Humans also trap them for their fur. North American river otters live for 10-15 years in the wild and can live as long as 25 years in captivity.

What kinds of things will I see in the exhibit?

The viewing window at the otter exhibit lets you get very close to them. The otters move a lot—in fact they never stop—so they can be challenging but fun to observe.

Continue your research!

The Alaska Wildlife Notebook Series has a great article about river otters.

Also, Yak's Corner is an online magazine for kids that has an archive of "Amazing Animals," including the otter.

Find a lot more animal and zoo sites on the Links Page!

You can also go back to the animal list.


Images © 1997, 1998, 1999 Chicago Zoological Society. Brookfield Zoo is owned by the Forest Preserve District of Cook County and managed by the Chicago Zoological Society.