River otters live in marshes, lakes, ponds, streams and estuaries. Their homes range from coastal areas to high mountain lakes. They once lived in waters throughout the United States and Canada. After European settlement, they became prized for their pelts and were eliminated from large areas through hunting. Recently, otters have been reintroduced in some parts of their range, such as Colorado and Virginia. They are carnivores.
Did you know?
- River otters are members of the weasel family.
- Otters stay active all winter, even in deep snow.
River otter lingo
River otters live in three types of freshwater habitats:
- Riverine: rivers or creeks and the pools in them
- Lacustrine: the deep and shallow waters of lakes
- Palustrine: wetlands or marshes
River otter behavior and facts
- River otters have short, dense brown fur with a waterproof undercoat. Their thick fur helps provide an insulating barrier against cold waters.
- The river otter has a torpedo-shaped head, webbed feet, and ears and nostrils that close underwater. A river otter can remain underwater for six to eight minutes and swim up to seven mph.
- They're diurnal (active during the day). But with human disturbance, they may become crepuscular (active during dawn and dusk) or nocturnal (active at night).
- They are usually not far from water. They often move into the former dens of beaver or muskrat, with an entrance below the waterline and above for air exchange
- In areas where waterways freeze in winter, otters find open water, such as a lake outfall. When water levels drop in late winter, otters hunt in the air space below the ice.
River otters' favorite food is the slowest fish in their environment. They are opportunistic feeders, eating whatever is nearby including mollusks, frogs, crayfish, turtles, insects and sometimes birds or small mammals.
From birth to death
- After mating, the implantation and development of the embryo is delayed eight or more months.
- Gestation: 60 to 63 days after implantation
- In late winter to early spring, pups are born in litters of two to four.
- Pups enter the water at seven weeks, are weaned at three months, and leave their mother at 12 months.
- Maturity: 2 years old
- Lifespan: eight to nine years in the wild; up to 18 years in captivity
- 10 to 30 pounds
- 21 to 32 inches long
- 12- to 20-inch tail
River otters are relatively abundant in unpolluted river systems and the lakes and tributaries that feed them. They are scarce in heavily settled areas, especially if waterways are polluted.
Because of habitat destruction and water pollution, river otters are listed as rare under CITES App II (except in the Pacific Northwest). Good populations exist in suitable habitat in the northeast and southeast part of Oregon. They are protected and regulated by the Oregon Department of Fish and Wildlife.
River otters, the Oregon Zoo and you
The zoo's river otters live in the Cascade Stream and Pond exhibit. They eat fish with vitamins, omnivore biscuits, ground horse meat, mice, insects and occasionally crayfish. Otter populations declined due to trapping and the loss or degradation of their habitat. They have recovered from some earlier declines. Help otters continue to enjoy life along the water by joining a conservation organization that works to preserve or restore otter habitats, such as the Columbia Land Trust.