The North American river otter occurs throughout Canada and the United States, except for areas in southern California, New Mexico and Texas, and the Mohawa Desert in Nevada and Colorado.
Otters were exterminated from many of their natural areas, but with the help of conservationists they were reintroduced and other efforts have helped the otters to stay there.
The North American otter thrives where there is plenty of food for them and access to water.
The otter can live in all types of water if food and winter open water are available. Saltwater also works well, but they need fresh water to be able to keep their coat trim. They live in rivers, lakes, marshes, swamps and estuaries. The North American river otter is sensitive to pollution and moves from areas where the water has been affected.
North American river otters build their burrows in other mammal burrows, or in natural caves, like under a log. The otter creates underwater entrances with tunnels leading to the cave. Their nest is filled with leaves, grass, moss, bark and hair.
North American river otters live both in water and on land. The otter’s body is streamlined with a thick tail and short legs. The head is round and wide with small eyes. Otter nostrils can close themselves underwater. The otters’ vibrissae are long and thick. The back of the otter is dark brown, almost black with a lighter colour on the belly. The cheeks and neck are golden brown.
The North American otter’s fur is soft and dense. It helps to keep the otter warm in the water. The paws have sharp claws with swimming skin between the pads. The pads leave a clear footprint, as the undersides of the feet are hairless. On solid ground, the otter usually moves at a gallop, leaving three or four tracks. In loose snow, it moves in pairs with a jump of about 50 cm. Body length varies between 88-130 cm. The tail is between 30-50 cm long. The weight is between 5-14 kg. Males are usually larger than females.
Males and females do not socialize except during the mating season. The otter male often mate with several females that are adjacent to the male’s area. The mating takes place during late winter or early spring.
The North American river otter female is pregnant for two months, but it can take up to a year before the kits are born. This is because otters use delayed implantation of the fertilized egg in the uterus. So the otter can have its litter from November to May, but most are born in March-April.
A litter consists of 1-6 kits but usually there are just two or three. They are born in the otter’s burrow near the water. When they are born, they have a protective coat but other than that they are completely helpless.
It takes a month before they open their eyes and they feed from their mother for about three months.
When the kits are between six months and one year old, they begin to leave the area where they were born. They become sexually mature between 2-3 years of age.