Otters are well known and loved for their playful antics and method of eating food on their tummies as they float on the water. But one variety of otter, the North American river otter, is well known throughout Canada and the United States for more than its gregarious nature.
Here, we’ll learn about what river otters eat, how they hunt, and where they live. Then, we’ll explore what zoos feed their captive otters, and how they keep them occupied. Finally, we’ll discover what baby otters are called, what they eat, and how old they have to be before they leave the den.
What Do River Otters Eat?
River otters eat mainly fish, crayfish, and other small, living creatures. They are carnivores.
North American river otters live across Alaska and Canada, and in the continental United States throughout the Pacific Northwest, New England, the east coast, and along the southern coast. Their diet is determined by the regional availability, abundance, and relative ease of hunting of prey creatures.
River otters eat fish overwhelmingly; over 90% of their diet often consists of fish. In particular, they target fish that are easy to hunt. Their second favorite food is crayfish. River otters also eat:
- Fish: slow moving and easy to catch; perch, suckers, catfish, sunfish, bass, daces, carp, shiners, rehorses, chub, bullheads, darter, and squawfishes
- Amphibians: frogs, toads, newts, and salamanders
- Molluscs: freshwater clams and mussels
- Insects: snails, beetles, stoneflies, and dragonflies
- Water snakes
- Mammals: water rats, mice, voles, cottontails, hares, muskrats, squirrels
It may seem like river otters eat anything in sight, but there are a few things they turn their noses up at. River otters will not eat carrion (dead meat), and they also don’t eat bird eggs (at least, in the wild).
How Do River Otters Hunt?
When it comes to river otters and hunting, ease is the name of the game. River otters are semi-aquatic ambush predators who do most of their hunting in the water. Slow moving, easy to catch fish are their favorite prey. River otters can hold their breath for up to eight minutes, plenty of time to find and catch something good to eat. Otters have good senses of hearing and smell, and they’ve even developed a special eyelid that allows them to see underwater.
Once the river otter finds its prey, it rushes forward, taking the fish, crayfish, or other unfortunate creature by surprise. They pin the prey in their jaws and, if big enough, take it to land to devour.
During the spring, summer, and fall, river otters are mostly nocturnal and crepuscular (active at dawn and dusk). During the winter, particularly in the northern hemisphere where daylight hours are short, they become more diurnal.
Otters and Their Dens
River otters are semi-aquatic, they can be found in almost any source of freshwater that provides a steady supply of food, but they don’t sleep in the water. For this, they use dens.
River otters don’t dig their own dens though, they hijack them from other animals and add their own tunnel entrance/exits. They prefer to have tunnels exiting to both land and water. Other than young otters, river otters have not been observed eating in their dens. Usually, with small prey, they eat directly in the water. Otters have to eat about 20% of their body weight every day, it’s no wonder they don’t haul all that food back to the den to devour.
What Do Captive River Otters Eat?
Many zoos keep rescued river otters. River otters are relatively easy to keep in captivity, though they should never be kept as pets. Zoos often provide semi-aquatic environments that mimic running streams or marshlands. It’s important that river otters always have a source of fresh water, as well as denlike areas to sleep in.
But what do captive river otters eat? Like their wild counterparts, these river otters are fed fish, and a lot of it. Because they have such high metabolisms, river otters have to be fed at least three times a day.
But zoos don’t stop at fish three times per day. River otters are used to having to work for their food, they’re also used to spending most of their day foraging. So, zoos will often supplement their river otters with scattered, or hidden, food like insects, crustaceans, and meat. Caretakers even feed boiled eggs to their river otters as a treat. With proper care and nutrition, captive river otters can live as long as 25 years. Wild river otters often live up to 12 years.
What Do Baby River Otters Eat?
River otters are sexually mature around two years of age. They’re polygynous, which means one male mates multiple females. The females are solely responsible for the care of their young, called pups. They usually have between 2-4 pups in the springtime, though they may have up to six.
Pups are born blind and toothless, but fully furred. They stay in the den and are completely reliant on their mother for the first month of life. During their first few weeks, they eat only mother’s milk.
Once the pups are around ten weeks old, the mother starts bringing them insects and small prey to eat. They are completely weaned by the time they are three months old, though the mother will continue to provide them with meals until they are nearly a year old.