The North American River Otter's scientific name is Lontra canadensis. The common name, River Otter, has two sources: "RIVER" tells the kind of habitat they like best, and "OTTER" is derived from Anglo-Saxon words oter or otor.
The River Otter is a supreme aquatic predator. It is a mammal whose body is elongated, covered with a dense fur, and reach a body length of from 35 1/2 -53 inches from nose to tip of the tail. Otters have a broad flattened head, conspicuous nose pad which is black, several long whiskers, rather small eyes and tiny ears. Their body is cylindrically shaped. They have a very muscular neck that is about the same diameter as the head Their tail is somewhat flattened on the underneath side, very thick at the base where it connects with body, and is used to help propel the animal and guide it through the water while swimming They have short stubby legs, equipped with five toes on each foot. The toes have heavy webbing in between each toe which aid in swimming. They have valvular ears and noses which means that when they go under the water their nose and ears automatically close permitting them to stay underwater with no problem of water entering the ears or nose. Most otters are a dark chocolate brown color. But some are even a light tan color. Their underparts are usually a lighter color ranging from pale brown to gray. Their muzzle and throat are silvery in color and at a distance their chin looks almost white. The males and females are colored alike and they have two pelage changes per year.
The males are usually larger than the females. Most adult males weigh between 22 and 30 pounds. The adult females weigh in at from 14 to 22 pounds. In captivity otters have been known to live for up to 19 years. In the wild they usually do not live quite that long. Otters are members of the Weasel Family, which include the Wolverine, Pine Martin, Fisher, Sea Otter, Badger, Skunk(s), Weasel(s), Ferrets, and Mink. All of these animals have a pair of scent glands located in the area of the anus. When frightened or excited these animals give of a strong pungent odor. The strong musk smell of otters is not as offensive as that of the skunk, and dissipates more rapidly. Otters have a wide range of vocalizations. They chirp, growl, grunt, snarl, and scream. They even give a growl-like vocalization while swimming under water. This occurs when they are irritated. Members of a family often communicate while traveling together by chirping: This is like saying, "Here I am, Where are you?' They do this quite often.
Otters have sharp claws and sharp teeth. They can have either 36 or 38 teeth and it is not known why the variation. River Otters can live in most aquatic environments that are clean. They can survive in both marine environments (salt water) as well as freshwater environments They live in streams, rivers, lakes, and even farm ponds. They make their homes in the abandoned dens of muskrats and beavers and occasionally that of a woodchuck if located reasonably close to the water There is usually an above water approach to the den as well as an underwater entry. Otters will carry nesting material consisting of leaves and grass to line the nest chamber.
Male River Otters have a large home range. They may travel over 50 to 100 miles of shoreline. Females travel a lot smaller area, especially when she has young, and the family may stay in an area of between 4 and 10 linear miles. Otters do not have to stay in the water all the time. Sometimes they travel over land for several miles in search of new territories and food supplies.
River Otters are nocturnal, at least most of the time. They spend most of the daylight hours sleeping. At dusk they awaken and begin their night patrol by hunting for something to eat. After feeding, they find time to play and frolic which is one of their favorite pastimes. They are active all year-round; they do not hibernate like a chipmunk, or groundhog, or a prairie dog. Cold weather does not inhibit their activities, in fact they love the cold weather with its ice and snow.
Otters are powerful but graceful swimmers. Sometimes they swim with just their faces showing above the water. They are difficult to distinguish from muskrats or beavers when swimming: especially if you can not see their tail or if they do not dive. They can stay under the water for 3 to 4 minutes. They enjoy swimming so much that they often swim for 5 or 6 hours at a time, stopping only to rest for a minute or two and then continue to pursue their favorite water sport.
The River Otter is an aquatic predator and feeds primarily on other animals. Crayfish are their favorite summer food. In the summertime crayfish make up about 90 percent of their diet. But in the wintertime when most species of crayfish go dormant in the mud, otters shift to an almost all-fish diet. This gets them in trouble with people who also like fish for food or sport.
Catfish farmers, farm pond owners, and sport fishermen who like to catch smallmouth bass and rock bass dislike otters because of their feeding habits. Otters supplement their diets with other foods including; frogs, salamanders, snakes, snails, clams, turtles, small birds, (sometimes even ducks), muskrats, and a variety of insects and earthworms. They often eat small amounts of vegetation.
When feeding on fish with scales, an otter often starts eating at the tail. A hungry otter can consume the entire fish if it weighs less than a pound. They often leave behind parts of larger fish. Some otters kill fish for sport When feeding on catfish, the otter will usually leave the head untouched eating only the soft body parts. The bones of a fish do not discourage an otter from "eating the whole thing"! ! ! Food passes through the digestive tract rapidly. The remains of an otter's meal can often be found in fresh droppings within an hour after they have eaten the prey. Their large droppings contain the remains of indigestible parts of fish and crayfish that they have eaten in previous meals. Biologists collect these droppings and study their contents to get an idea of what the otter has been eating. Skeletal parts of crayfish and the scales of fish pass through the digestive tract, do not break down, and can be found in the droppings as telltale evidence of what otters like to eat.
Female river otters come into breeding condition any time from December to May. Females who have given birth recently, mate within a short period of time following birthing. Following the mating, the sperm and ovum unite forming a blastocyst. This will someday develop into a baby otter. After conception, the blastocyst floats freely in the uterus of the mother-to-be for several months. Usually in late January, the blastocyst implants in the wall of the uterus and a baby otter is on the way!!! This phenomenon is known a s "delayed implantation".
Baby otters are called puppies. They are usually born from January to May. They are born a charcoal brownish color. They are covered with very fine, tiny, hairs. Their eyes are closed when they are born and finally open at about 28 to 30 days after birth. Their ears are also closed and they open at about 14 days. Otter pups weigh about 2 ounces when born. They are born toothless but teeth begin to erupt through the gums in about a week after birth. There are usually 2 to 4 puppies per litter. Litters with I puppy or 5 puppies are the extremes. The babies are weaned from their mother's milk at about 4 months of age. They learn to swim at about 3 months of age. Baby otters are very fearful of water when first introduced to it. The female has to coax them often dragging them into the water for their first swim After about 3 days, the babies figure it out and then it is difficult for them to stay out of the water. The otter pups will stay with their mother for up to a year. The little family is a tight-knit social group and will most often be seen together, playing, fishing and just enjoying being an otter!!!