page_title: North American river otter
section_title: Social behavior
hierarchical_section_title: North American river otter / Behavior / Social behavior
caption_attribution_description: English: Pair of Lontra canadensis in captivity in Phillips Park Zoo in Aurora, Illinois
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: The North American river otter is more social than most mustelids. In all habitats, their basic social group is the family, consisting of an adult female and her progeny. Adult males also commonly establish enduring social groupings, some documented to comprise as many as 17 individuals. In coastal areas, males may remain gregarious even during the estrous period of females. Family groups may include helpers, which can be made up of unrelated adults, yearlings, or juveniles.
  Male North American river otters disperse from such family groups more often than females. When females leave, they tend to move much further away (60–90 km or 37–56 mi) than males (up to 30 km or 19 mi), which tend to move shorter distances. Male North American river otters do not seem to be territorial, and newly dispersing males may join established male groups.
  On occasion, groups of unrelated juveniles are observed. North American river otters living in groups hunt and travel together, use the same dens, resting sites, and latrines, and perform allogrooming. In freshwater systems, groups occur most often in autumn and during early winter. From mid-winter through the breeding season, adult females move and den alone. River otters are not territorial, but individual North American river otters of different groups portray mutual avoidance. Home ranges of males are larger than those of females, and both sexes exhibit intra- and intersexual overlap of their domains.
caption: A pair of captive North American river otters at Phillips Park Zoo in Aurora, IL.
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