The North American River Otter is
problably the most numerous otter species. They exhibit delayed implantation
with breeding in March-April and birth in late winter/early spring. Fossils
of North American River Otters have dated back to the Pleistocene period
and archeological remains have been uncovered from 200 B.C. to the mid-1400s.
North American River Otters once
lived throughout North America. Native Americans hunted otters largely
for their dense fur which allowed them to keep warm. When European settlers
arrived and started developing the land (cutting down forests) and using
farm pesticides and fertilizers, the otter habitat became threatening.
By the early 1980s, eleven states reported no otter population and thirteen
other states reported scarce numbers. As a result, numerous reintroduction
programs were established to repopulate many of these areas. By late 1990s,
many of these programs had successes with a dramatic improvement in returning
otters to their original range.
North American river otters are found
anywhere there is a permanent food supply and easy access to water. They
can live in freshwater and coastal marine habitats, including rivers, lakes,
marshes, swamps, and estuaries. River otters can tolerate a variety of
environments, including cold and warmer latitudes and high elevations.
North American river otters seem to be sensitive to pollution and disappear
from areas with polluted waters.
North American river otters build
dens in the burrows of other mammals, in natural hollows, such as under
a log, or in river banks. Dens have underwater entrances and a tunnel leading
to a nest chamber that is lined with leaves, grass, moss, bark, and hair.
5 to 14 kg
(11 to 30.8 lbs)
889 to 1300 mm
(35 to 51.18 in)
North American river otters are semi-aquatic
mammals, with long, streamlined bodies, thick tapered tails, and short
legs. They have wide, rounded heads, small ears, and nostrils that can
be closed underwater. The vibrissae are long and thick, reflecting their
importance in sensory perception. The fur is dark brown to almost black
above and a lighter color ventrally. The throat and cheeks are usually
a golden brown. The fur is dense and soft, effectively insulating these
animals in water. The feet have claws and are completely webbed. Body length
ranges from 889 to 1300 mm and tail length from 300 to 507 mm. Weight ranges
from 5 to 14 kg. Males average larger than females in all measurements.
Breeding interval: Breeding occurs
Breeding season: Mating occurs in
late winter and early spring.
Number of offspring: 1 to 6; avg.
Gestation period: 2 months (average)
Time to weaning: 3 months (average)
Time to independence: 6 to 12 months
Age at sexual or reproductive maturity
(female): 2 to 3 years
Age at sexual or reproductive maturity
(male): 5 to 7 years
Males and females do not associate
except during the mating season. Males often breed with several females,
probably those whose home ranges overlap with their own.
Males and females come together to
breed in late winter or early spring. Gestation lasts two months, but the
young may be born up to a year after mating because these otters employ
delayed implantation of the fertilized egg in the uterus. Births occur
from November to May, with a peak in March and April. Females give birth
to from 1 to 6 young per litter, with an average of 2 to 3, in a den near
the water. They are born with fur, but are otherwise helpless. They open
their eyes at one month of age and are weaned at about 3 months old. They
begin to leave their natal range at from 6 months to a year old. Sexual
maturity is reached at 2 to 3 years of age.
Females give birth to, nurse, and
care for their young in a den near the water. The young are weaned at about
3 months old and begin to leave their mother at 6 months old.
North American river otters can live
up to 21 years in captivity. They normally live about 8 to 9 years in the
Lontra canadensis individuals are
solitary, except for females with their young. They are known as playful
animals, exhibiting behaviors such as mud/snow sliding, burrowing through
the snow, and waterplay. Many "play" activities actually serve a purpose.
Some are used to strengthen social bonds, to practice hunting techniques,
and to scent mark. North American river otters get their boundless energy
from their very high metabolism, which also requires them to eat a great
deal during the day.
They are excellent swimmers and divers,
able to stay underwater for up to 8 minutes. They are also fast on land,
capable of running at up to 29 km/hr. These otters normally hunt at night,
but can be seen at all times of day.
River otters have large home ranges,
between 2-78km of waterway, and are constantly on the move within this
range. Home range sizes vary considerably and seem to depend on the richness
of food resources and habitat quality. Despite these large ranges, river
otters are only slightly territorial and generally practice mutual avoidance.
Communication and Perception
North American river otters communicate
in a variety of ways. They vocalize with whistles, growls, chuckles, and
screams. They also scent mark using paired scent glands near the base of
their tails or by urinating/defecating on vegetation within their home
range. These glands produce a very strong, musky odor. They also use touch
and communicate through posture and other body signals.
North American river otters perceive
their environment through vision, touch, smell, and hearing. Their large
and abundant whiskers are very sensitive and are important in tactile sensation.
These whiskers are used extensively in hunting, as smell, vision, and hearing
are diminished in the water.
North American river otters eat mainly
aquatic organisms such as amphibians, fish, turtles, crayfish, crabs, and
other invertebrates. Birds, their eggs, and small terrestrial mammals are
also eaten on occasion. They sometimes eat aquatic plants.
Prey is captured with the mouth, and
mainly slow, non-game fish species are taken, e.g., suckers. The otter's
long whiskers are used to detect organisms in the substrate and the dark
water. Prey is eaten immediately after capture, usually in the water, although
larger prey is eaten on land.
North American river otters are sometimes
taken by bobcats, coyotes, birds of prey, and other large predators.
They mainly escape predation through their agility in the water and on
land, their vigilance, and their ability to fiercely defend themselves
and their young.