OtterTop
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.Top
North American river otters are rich brown on top, with a silvery sheen on the bottom.
They have webbed feet and a tail that is thick at the base and tapers to the tip. River
otters have a long neck, short legs, a flat head, strong claws, whiskers, and no hair on
their nose. They have a layer of fat under their skin and dense, oily fur that protects
them from cold. Males are slightly larger than females, with a head and body up to 66-127
cm long. Their tail can grow up to 43 cm. They can weigh between 4.5 and 11 kg. Top
North American river otters can move on land and in water. They are found mostly in the
water. They have a streamlined body, and their eyes and ears close under water. When North
American river otters are on land, they walk on all four legs. Top
North American river otters communicate by chirping, chattering, and chuckling. They
have a hair-raising scream they use when frightened. It can be heard 2 km away. Top
A pair of otters are together only a short time during breeding season. Otters are best
known for the amount of time they play. They like to chase, wrestle, dive for rocks and
clamshells, capture and release live prey, and slide on things. Some scientists believe
that this play provides young otters with experience and strengthens and sharpens their
reflexes. Otters usually have a home range of 25 km or so, but they may wander for 90 km
or more. Top
Male and female otters are ready for reproduction at about two years of age. A female
otter is pregnant for 10 to 12 months, with a litter of one to six. After mating, these
otters can exhibit “delayed implantation.” The fertilized egg can remain in the
uterus for up to nine months. Once the egg is implanted in the uterine wall, its
development continues for 60 days. Young otters are helpless at birth and do not open
their eyes until they are three weeks old. When they are about 60 days old, they leave the
den and are introduced to the water. The female cares for the young otters and teaches
them to swim, catch prey, and look for food. Young otters can care for themselves in about
five to six months, but the family often stays together until the birth of a new litter. Top
River otters eat fish, crustaceans, insects, birds, muskrats, and clams. Top
North American river otters are endangered in some states, and are threatened in Illinois. They are abundant in Canada, Alaska, and the Pacific Northwest. Pollution and pesticides cause serious problems for river otters. Their habitats are being destroyed by humans. Humans also trap them for their fur. North American river otters live for 10-15 years in the wild and can live as long as 25 years in captivity. Top
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