35 to 54 inches. Weight: 11
to 33 pounds.
Inhabits streams, rivers, and lake borders.
Riparian vegetation is a key component of otter
habitat. Otters often use bank dens first
created by beavers. Availability of food,
water, and shelter determine the duration and
intensity of habitat use.
The otter dies is primarily fish, but it will
consume a variety of aquatic prey.
Active both day and night. One of the most
aquatic members of the weasel family. Sociable
animal that dens in banks with entrance below water.
Breeds during spring; 9.5 to 10 month gestation;
delayed implantation; litter size of 2 to 3 is most
Beaver - has a flat, scaly tail. Mink - much
smaller, feet not webbed.
River otter are highly
skilled swimmers. Rough fish make up a substantial
portion of an otter's diet, although game fish of
medium size are occasionally caught and eaten. Great
travelers, otter circuits may cover 60 or more
miles, and take weeks to complete. This species
enjoys play, and otters commonly play either alone
or with others of their kind. Powerful and
streamlined furbearers, otter are recognized as one
of the more intelligent species.
Otter have long, slender bodies with relatively short
legs. The neck is long and muscular, as is the tapered
tail. Otter fur is considered as a short haired fur.
Guard hair lengths are about one inch with under fur
lengths of about 3/4 inch. Coloration is brown,
with chocolate colors common in southern states, and
darker colors common in northern states. Otter from all
areas are lighter in color on cheeks, throats and
Males are larger than females.
Adult males may measure 48 inches in length, and weigh
up to 25 pounds. Adult females are usually 4 to 6 inches
shorter, and seldom weigh more than 19 pounds.
There are 5 toes on each foot. A
web of skin connects the toes on each foot. Claws are
strong and nonretractable. Otter have 36 teeth,
including 4 long and sharp canine teeth. Valves are
present in an otter's nose and ears which close
automatically as the otter submerges.
A pair of anal musk glands are
present on both males and females. This musk can be
released when the otter is frightened, but it is not as
offensive as the musk of other members of the mustelid,
or weasel, family.
Breeding occurs over most of the otter range during
March and April, only a few days after the litter is
born. Males leave after breeding to find other females,
but may return 6 to 8 weeks later to join the family.
Delayed implantation occurs, and
this varies a great deal. Implantation of the fertilized
eggs may take 7 to 10 months before the free-floating
eggs attach themselves to the uterus walls to complete
the 60 to 65 day gestation. Litter sizes average 2 or 3,
with 4 being uncommon. Most otter do not mate until they
are two years old.
Abandoned beaver dens are often
selected by the female otter for the natal dens. At
times, an otter will use a dry land den near the water
to raise the litter. All young must be taught to swim.
Except for the raising of the litter, otter seem to be
constantly on the move from place to place. They do not
seem to defend their territories from other otter, and
overlapping of regular territories do occur often.
The availability of food, as
well as the season, determines how far the individual
otter ranges. During summer months when food is easily
available, otter may stay within a 20 square mile area.
during winter conditions, the same otter may circulate
over 60 or more square miles. Circuit times vary as
well, and an otter may complete a summertime circuit in
a week as compared to wintertime travels taking 3 or 4
Otter commonly travel by
swimming and loping along shorelines, but they do not
hesitate to take off overland to reach a distant steam
or pond. These overland trails may be very distinct when
otter populations are high.
Otter certainly enjoy sliding on
mud or snow. Under favorable conditions, they might
bound 3 or 4 times and then slide for yards before
continuing to bound and slide some more. Mud slides down
steep banks into the water are commonly used in many
northern areas as the otter or family of otter take
turns climbing the bank to slide down the slide into the
water head first.
Otter have a high metabolic
rate, and food passes through the entire digestive
system in about an hour. Small fishes are eaten whole.
Often an otter will eat a fish while floating in the
water on its back, holding the fish much like a person
eating corn on the cob. After eating, otter commonly
vomit up an abundance of fish scales and bones. This
prevents a large number of valueless scales from passing
through the entire digestive system.
The elongated body, webbed feet
and powerful tapered tail allow the otter to be very
quick in the water, and they can swim at least 1/2 mile
while submerged. When an otter chooses to swim quickly,
it undulates its entire body up and down in a ship-like
fashion with their front legs held tightly to the body.
Commonly eaten foods include
many types of minnows, sunfish, suckers, perch and
scullions in western habitats. Also eaten are
crayfish (claws not eaten), water snakes, frogs, and
aquatic insects. Muskrats are eaten when available, as
Otter are not known to store
food. Although an otter does not kill more food than it
will eat, the high rate of metabolism keeps the
furbearer hungry much of the time.
Young otter will often stay with
their mother through their first winter season.
Oftentimes, the young will follow the mother in a single
file fashion, both on land and in the water.
Although otter can and do eat trout, they usually help a
tout stream by helping to contain populations of rough
fish. When fish are so abundant as to become stunted,
predation certainly allows more food for the remaining
fish. Although otter sometimes kill muskrats and ducks,
the numbers are so small as to be insignificant. Otter
can devastate fish farms. This is most apt to happen
during the spring when a family of otter may be denned
for 2 or 3 months.
Adult otters are rarely killed
by other predators. Lynx and wolves can kill them, and
juvenile otter may also be vulnerable to predation by
bobcats and coyotes.
Otter are relatively free of
parasites due to infrequent uses of dens, constant
traveling habits and little contact with other otter
that are not family members. However, they are
vulnerable to poisons which often show up in fish. Fish
killed by acid rain may poison otter, and lethal amounts
of DDT, PCB's, and mercury have been found in otter.
A significant habitat loss of
otter has occurred over much of their historic range.
Farming practices in many area allow muddy and silty
water with each rainfall, which discourages fish
production as well as interfering with an otter's
ability to locate food by sight.
Otter are considered to be old
at 15 years.
Best Management Practices
Special Regulations Note
STATEWIDE SEASON DATES:
November 1 - April 15 of the following year, except
state Wildlife Management Areas and specific closures
(See SPECIAL REGULATIONS). Season will close in 48 hours
upon reaching the trapping district quota or on the
season closure date, whichever occurs first.
The otter season on the Flathead Indian Reservation is
closed to all trappers (members and nonmembers).
Closures - All
areas closed to beaver trapping are also closed to otter
harvest quota information may be obtained by calling the
appropriate Fish, Wildlife & Parks regional office
during normal business hours or by calling
1-800-711-TRAP (1-800-711-8727) 24 hours a day or the
FWP website at fwp.state.mt.us. The toll free line and
website are updated by 1 pm. (MST) every day. Furbearer
seasons will close in 48 hours when a species quota is
reached prior to the end of the regular season.
The Fish, Wildlife & Parks
Commission has authorized the department to initiate a
closure prior to reaching a quota or subquota when
conditions or circumstances indicate the quota may be
reached within the 48-hour closure notice period.
Trappers are required to personally report their otter
harvest within 24 hours by calling the Fish, Wildlife &
Parks regional office during office hours (8 AM - 5 PM
weekdays) in the trapping district where the animal was
taken so that FWP can monitor quota levels. Reporting
can also be made after office hours and on weekends by
Trappers are required to personally present the pelts of
otter for tagging to a designated Fish, Wildlife & Parks
employee residing in the trapping district where the
animal was taken within five (5) days of harvest.
Trappers or hunters unable to comply with the five day
pelt tagging requirements due to special circumstances
or the unavailability of local FWP personnel must still
register their pelts within five days of harvest by
calling the proper regional office to make arrangements
for tagging by FWP personnel at a later time. Pelts not
presented or registered to department personnel within 5
days are subject to confiscation.
is mandatory that the entire and intact carcass of all
otter be turned into Fish, Wildlife & Parks in good
condition, at the time the pelt is presented for
tagging. The skulls will be retained by Fish, Wildlife &
Parks for processing and examination and then returned
to the owner if desired. Good condition is defined as
fresh or frozen and securely wrapped in such a manner as
to have prevented decomposition in order that all tissue
samples are suitable for lab analysis. Any otter pelt
that is presented for tagging without the carcass in
good condition shall be subject to confiscation.
federal export permit is required in addition to a
Montana CITES tag before the pelts of bobcat and otter
may be exported from the United States. Apply to U. S.
Fish and Wildlife Service, 600 Central Plaza, Room 209,
Great Falls MT 59401.