page_title: North American river otter
section_title: Movement
hierarchical_section_title: North American river otter / Behavior / Movement
context_page_description: The North American river otter, also known as the northern river otter or common otter, is a semiaquatic mammal endemic to the North American continent found in and along its waterways and coasts. An adult North American river otter can weigh between 5.0 and 14 kg. The river otter is protected and insulated by a thick, water-repellent coat of fur.
  The North American river otter, a member of the subfamily Lutrinae in the weasel family, is equally versatile in the water and on land. It establishes a burrow close to the water's edge in river, lake, swamp, coastal shoreline, tidal flat, or estuary ecosystems. The den typically has many tunnel openings, one of which generally allows the otter to enter and exit the body of water. Female North American river otters give birth in these burrows, producing litters of one to six young.
  North American river otters, like most predators, prey upon the most readily accessible species. Fish is a favored food among the otters, but they also consume various amphibians, freshwater clams, mussels, snails, small turtles and crayfish. The most common fish consumed are perch, suckers, and catfish.
context_section_description: North American river otters swim by quadrupedal paddling, forelimb paddling, alternate hind-limb paddling, simultaneous hind-limb paddling, or body and tail dorsoventral undulation. The tail, which is stout and larger in surface area than the limbs, is used for stability while swimming and for short bursts of rapid propulsion. While swimming at the surface, the dorsal portion of the North American river otter's head, including nostrils, ears, and eyes, is exposed above water. It must remain in motion to maintain its position at the surface.
  On land, the North American river otter can walk, run, bound, or slide. Foot falls during walking and running follow the sequence of left limb, right limb, right limb, left limb. During walking, the limbs are moved in a plane parallel to the long axis of the body. Bounding is the result of simultaneous lifting of the limbs off the ground. As the front feet make contact with the ground, the back feet are lifted and land where the front paws first contacted the ground, producing a pattern of tracks in pairs typical of most mustelids. Sliding occurs mostly on even surfaces of snow or ice, but can also occur on grassy slopes and muddy banks. Sliding across snow and ice is a rapid and efficient means of travel, and otters traveling over mountain passes, between drainages, or descending from mountain lakes often slide continuously for several hundred meters. Rear leg paddling enables continuous sliding where gravity is an insufficient or an opposing force. During winter, the North American river otters heavily use openings in the ice, and may excavate passages in beaver dams for accessing open water.
  North American river otters are highly mobile and have the capacity of traveling up to 42 km (26 mi) in one day. Daily movements of yearling males and females in Idaho averaged 4.7 and 2.4 km (2.9 and 1.5 mi) in spring, 5.1 and 4.0 km (3.2 and 2.5 mi) in summer, and 5.0 and 3.3 km (3.1 and 2.1 mi) in autumn, respectively. Daily movements of family groups averaged 4.7, 4.4, and 2.4 km (2.9, 2.7, and 1.5 mi) in spring, summer, and winter, respectively. Both males and family groups travel drastically less during winter.
caption: Sliding across ice is an efficient means of travel. Note the long, tapered tail.
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