Do Otters Build Dams in Rivers? Because otters and beavers are both aquatic mammals, people often get them confused. Some even wonder if otters build dams like beavers. However, the animals are different in many aspects of their habits and appearance. Otter Dens Although otters do not build them, they will sometimes use abandoned dams. These have hidden, underwater entrances for protection from predators, which makes them attractive to otters. Any burrow or den taken over by these animals is called a holt. Other Shelters Preferring multiple resting places, these animals typically have more than one shelter in their home range, sometimes even denning in a hollow log. In addition, an otter has a latrine that is separate from the main den. Identification Well-adapted for swimming, otters have long, sleek bodies, webbed feet, and a muscular, cat-like tail. In contrast, beavers are stocky with a distinctive broad, flat tail. Problems Caused by Otters Just because otters don't build dams, it doesn't mean they are harmless to property. These meat-eating pests can affect local fish populations and leave discarded bones littered along shores and riverbanks. When otters become a nuisance, Critter Control can safely remove the problem.