River otters are found all along the east coast of the US, northern parts of the Midwest, in the Pacific Northwest, and most of Canada. They live in dens along the banks of rivers and lakes. Sometimes otters will dig their own dens or else use hollow logs, overhanging roots or other empty animal burrows. The dens have underwater and aboveground entrances. During the winter, otters can breathe in the space between the bottom of the ice and the lowering water.
Otters eat lots of fish but also mice and small invertebrates such as crayfish.
They primarily eat slow moving fish like suckers and catfish. Otters use their whiskers to locate crayfish, turtles, and fish along the bottom of the water. Sometimes otters work together as a team and scare the fish into small alcoves in the water where they can be caught easily. Otters have litters of between 1 and 6 cubs. Two is the most common number of cubs in a litter.