North American River Otter
Lontra canadensis
Summary 2
The North American river otter (Lontra canadensis), also known as the northern river otter or the 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 (11.0 and 30.9 lb). 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 (Mustelidae), 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 underground burrows, producing litters of one to six young.[2]
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 (such as salamanders and frogs[3]), freshwater clams, mussels, snails, small turtles and crayfish. The most common fish consumed are perch, suckers, and catfish.[4] Instances of North American river otters eating small mammals, such as mice and squirrels, and occasionally birds have been reported as well. There have also been some reports of river otters attacking and even drowning dogs.[5][6][7]
The range of the North American river otter has been significantly reduced by habitat loss, beginning with the European colonization of North America. In some regions, though, their population is controlled to allow the trapping and harvesting of otters for their pelts. North American river otters are very susceptible to the effects of environmental pollution, which is a likely factor in the continued decline of their numbers. A number of reintroduction projects have been initiated to help halt the reduction in the overall population.[8]
The North American river otter is a stocky animal of 5 to 14 kilograms (11 to 31 lb), with short legs, a muscular neck no smaller than the head, and an elongated body that is broadest at the hips.[15] They have long bodies, and long whiskers that are used to detect prey in dark waters.[18] An average adult male weighs about 11.3 kilograms (25 lb) against the female's average of 8.3 kilograms (18 lb). Its body length ranges from 66 to 107 centimetres (26 to 42 in).[19] About one-third of the animal's total length consists of a long, tapered tail.[15] Tail lengths range from 30 to 50 centimetres (12 to 20 in).[19] Large male North American river otters can exceed a weight of 15 kilograms (33 lb).[20] It differs from the European otter by its longer neck, narrower visage, the smaller space between the ears and its shorter tail.[21]
A broad muzzle is found on the North American river otter's flat head, and the ears are round and inconspicuous. The rhinarium is bare, with an obtuse, triangular projection. Eyes are small and placed anteriorly. A short, broad rostrum for exhaling and a long, broad cranium define the relatively flat skull.[15] The North American river otter's nostrils and ears close during submersion, keeping water from entering them.[15] Its vibrissae (whiskers) are long and thick, enhancing sensory perception underwater and on land.[15]
The fur of the species is short (guard hairs average 23.8 mm (0.94 in)), with a density of about 57,800 hairs/cm2 (373,000 hairs/in2) in the midback section. The pelage has a high luster and varies from light brown to black. The throat, chin, and lips are grayer than the rest of the body. Fur of senescent river otters may become white-tipped, and rare albinos may occur.[15]
The North American river otter is sexually dimorphic.[22] Males are, on average, 5% larger than females. In Idaho, juvenile, yearling, and adult males averaged 8, 11, and 17% heavier, respectively, than females of the same age. A clinical reduction in size may exist from north to south along the Pacific coast, but not from east to west.[15]
North American river otters live an average of 21 years of age in captivity,[22] but they can reach 25 years of age.[15] In the wild, they normally live about 8 to 9 years in the wild,[22] but are capable of living up to 13 years of age.[15]
Sources and Credits
- (c) Dan Dzurisin, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/ndomer73/3205753344/
- Adapted by calgaryzoo from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Lontra_canadensis
