River otters, particularly the North American river otter, are cherished for their playful behavior and unique dining habits as they effortlessly float on water. Found across Canada and the United States, these endearing creatures have a lot more to offer than just their amusing nature.

In this article, we will delve into the diet and hunting techniques of river otters and their habitat preferences. We will also examine the way zoos cater to the dietary needs of captive otters and keep them entertained. Moreover, we will uncover the name given to baby otters, their food preferences, and the age when they venture out of their den independently.

What Do River Otters Eat?

River otters predominantly consume fish, making up over 90% of their diet. They prefer slow-moving and easy-to-catch fish such as perch, suckers, catfish, sunfish, bass, and carp, among others. Crayfish is also a favorite food item for these aquatic mammals.

In addition to fish and crayfish, river otters have a varied diet, which includes:

  • Amphibians: Frogs, toads, newts, and salamanders
  • Molluscs: Freshwater clams and mussels
  • Insects: Snails, beetles, stoneflies, and dragonflies
  • Reptiles: Water snakes
  • Mammals: Water rats, mice, voles, cottontails, hares, muskrats, and squirrels
  • Birds: Ducks

Despite this extensive list of prey, there are certain things river otters avoid consuming. They typically do not eat carrion (dead meat) and, interestingly, tend to pass on bird eggs in the wild.

These carnivorous mammals have a high metabolism and therefore require a significant amount of food to maintain their energy levels. The regional availability, abundance, and ease of hunting prey primarily determine the diet of river otters. Their short legs, webbed feet, and long tails make them well-equipped to navigate their aquatic habitats in search of tasty morsels.

How Do River Otters Hunt?

River otters, being semi-aquatic creatures, excel at hunting primarily in the water. They prefer slow-moving fish that are easier to catch. These skilled hunters can hold their breath for up to eight minutes, giving them sufficient time to search for a meal. Blessed with sharp senses of hearing and smell, river otters also possess a unique eyelid that enables them to see underwater.

When a river otter spots its prey, it quickly lunges forward and catches the fish, crayfish, or other creatures. Using their strong jaws, they hold the prey tightly and, if the size permits, carry it to land to enjoy their feast.

In the spring, summer, and fall, river otters tend to be mostly nocturnal and crepuscular – active during dawn and dusk. However, during winter, particularly in regions with shorter daylight hours, they adapt and become more active during the day.

Otters and Their Dens

River otters, being semi-aquatic mammals, reside in various freshwater sources as long as there’s ample food supply. Although they don’t sleep in the water, they rely on dens for shelter. Interestingly, river otters don’t build their own dens; they rather take over the existing dens of other animals, adding tunnel entrances and exits according to their preference. These clever creatures favor tunnels with access to both land and water.

Otters display strong social bonds and sharing dens contributes to this aspect. While young otters might feed within the dens, adults typically eat small prey directly in the water. Since otters consume around 20% of their body weight daily, bringing all the food back to the den might seem impractical.

What Do Captive River Otters Eat?

Captive river otters, often found in zoos, are well-taken care of in environments that closely resemble their natural habitats, with running streams or marshlands and den-like sleeping areas. Feeding them properly is crucial to maintain their health and well-being.

These otters primarily rely on fish as their main food source, and due to their high metabolism, they require feeding at least three times a day. However, to keep their foraging skills sharp and provide dietary variety, zoos offer additional food items:

  • Insects
  • Crustaceans
  • Meat

Occasionally, as a special treat, river otters may be given boiled eggs. This diverse diet helps ensure that the otters receive the necessary nutrients and remain healthy in captivity.b

By providing a well-rounded diet and proper care, captive river otters are known to have a potential lifespan of up to 25 years. This is considerably longer than their wild counterparts, which typically live for about 12 years.

What Do Baby River Otters Eat?

River otters reach sexual maturity at about two years old and follow a polygynous mating system, where a single male mates with multiple females. The female otters are fully responsible for taking care of their offspring, known as pups, and typically give birth to 2-4 pups during spring, although up to six pups can be born.

When the pups are born, they are blind, toothless, and covered in fur. Relying entirely on their mother, the pups remain in their den for the first month of their lives, feeding solely on their mother’s milk.

As the pups grow and reach around ten weeks old, the mother begins to introduce them to solid foods, bringing them insects and small prey. By the time they are three months old, the pups are completely weaned from their mother’s milk. Nonetheless, the mother continues to supply their meals until they are nearly a year old, ensuring the young otters are well-nourished and ready to thrive independently.

The diet of baby river otters starts with:

  • Mother’s milk (for the first month)
  • Insects and small prey (introduced at ten weeks old)

Keep in mind that female otters play a significant role in the nurturing and nourishment of their pups, providing them with appropriate food according to their growth stages and ensuring their well-being.

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