North American River Otter

River otters primarily eat aquatic animals like fish, amphibians, crayfish, and other small creatures that live in water. Sometimes, they also catch birds, small animals, and eat aquatic plants. Their diet can change based on where they live and the time of year. Otters are skilled hunters, using their sharp eyesight and sensitive whiskers to find prey in dark or murky water. They catch their food with their mouths and usually eat it right away in the water, though they might bring larger prey onto land to eat it.

At the Zoo, otters receive a specialized ground carnivore diet, lake smelt, capelin, and trout.

Before European colonization, river otters were found all across North America. They lived in many different wet areas, from icy Alaska and northern Canada down to the southern United States. However, by the mid-1950s, many river otter populations were wiped out, especially in crowded areas of the U.S. and southern Canada.

Recently, thanks to conservation efforts and reintroducing them to their old habitats, river otter populations have started to come back. Still, many of these otters are considered vulnerable or in danger, especially in the Midwestern United States and the Appalachian Mountains.

River otters are found along streams, rivers, ponds, lakes, reservoirs, and in saltwater marshes – basically any habitat where there is a permanent food supply and easy access to water. River otters can adapt to different environments, whether it’s cold or warm, and even at high altitudes. Often, they can be found near American beavers because beavers create ponds that give otters food and safe places to make their homes. However, North American river otters are impacted by pollution and tend to leave areas where the water is contaminated.

River otters have natural enemies, such as bobcats, birds of prey, alligators, and other large animals.

Although trapping is legal in many areas, unregulated harvesting for fur is a threat in some regions in the U.S. Pollution in the water, including trash and chemicals, makes it harder for otters to find food and can lead to harmful toxins that affect how they reproduce. In coastal regions, oil spills pose a significant danger to local river otter populations.

River otters are well-designed for living in the water. They have short, webbed feet that help them swim quickly. Their strong, flat tails allow them to change direction easily. The fur of an otter is a dark brown color, with a lighter gray on their chest and chin. When they swim, otters trap air in their fur to keep warm. This air gets warmed by their body heat and helps to insulate them from the cold water. If you watch otters swimming, you'll see bubbles rise to the surface, which is the warm air escaping.

After a swim, otters need to groom their fur to keep the air trapped and ready for their next swim. Their noses don't have fur but are surrounded by special sensitive whiskers, called vibrissae, that help them detect changes in their surroundings. The eyes of a river otter are positioned on the top of their head so they can see while swimming at the surface of the water. They have a special eyelid, known as a nictitating membrane, which helps them see when they are underwater. When they dive, their ears and nostrils close to keep water out. Otters also have sharp teeth that help them catch and hold onto their food quickly in the water.

Male and female river otters usually only come together during mating season. Males often mate with several females, depending on where they live, during late winter to early spring. After mating, the mother otters have a pregnancy that lasts about two months. However, they can give birth up to a year later because they can delay the development of the fertilized egg.

Typically, otters have two to three young between February and April, and they usually find a den close to water for the birth. The baby otters are born with fur, but they are blind and don’t have teeth. Their eyes open around one month old, and they start eating solid food instead of their mother’s milk around three months old. The young otters will leave their home range when they are between six months and a year old. They reach sexual maturity when they are about two years old.

Otters, like other animals in the weasel family, have special glands near the base of their tails. These glands produce a strong smell that helps them communicate and mark their territory. The smell, along with their urine and feces, sends signals to other otters.

River otters are quite talkative and make different sounds, such as whistles, buzzes, chirps, and chuckles. They also use their body language, like touch and posture, to communicate with each other.

North American river otters are known for their incredible energy, which comes from a very high metabolism. This means they need to eat a lot of food every day. Most of the year, otters are active from dusk until dawn, but in the winter, you might see them during the day more often.

Otters can live alone or in family groups, usually consisting of females and their young. They are great swimmers and can travel long distances under ice during winter, holding their breath for up to four minutes and swimming as fast as seven miles per hour! When they need to move between water sources on land, otters often slide on their bellies and use their back legs to push themselves along, especially in the snow or on slick banks.

This sliding, along with other playful activities, helps them strengthen their social bonds, practice hunting skills, and mark their territory with their scent.