HABITAT AND 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.
They also tolerate a variety of
environments, including cold and warmer
latitudes and high elevations. North
American river otters once occurred
throughout Canada and the United States,
with a few exceptions. In Mexico they
are found in the delta areas of the Rio
Grande and Colorado river. These otters
are now rare or locally extinct
throughout much of the eastern, central,
and southern United States.
PHYSICAL CHARACTERISTICS:
North American river otters are
semi-aquatic mammals, with long,
streamlined bodies, thick tapered tails,
and short legs. The vibrissae are long
and thick, reflecting their importance
in sensory perception. The fur is dense
and soft, effectively insulating these
animals in water. The feet have claws
and are completely webbed. Males average
larger than females in all measurements.
ADAPTATIONS:
North American river otters seem to be
sensitive to pollution and disappear
from areas with polluted waters. They
also 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.
DIET:
These river otters eat mainly aquatic
organisms such as amphibians, fish,
turtles, crayfish, crabs, and other
invertebrates. Birds, their eggs, small
terrestrial mammals and aquatic plants
are also eaten on occasion.
REPRODUCTION AND DEVELOPMENT:
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. Males and
females do not associate except during
the mating season (late winter or early
spring). Males often breed with several
females, probably those whose home
ranges overlap with their own. Gestation
lasts approximately two months. 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. North
American river otters can live up to 21
years in captivity. They normally live
about 8 to 9 years in the wild.
STATUS IN WILD:
These otters are now rare or locally
extinct throughout much of the eastern,
central, and southern United States.
