This large member of the vole
family has a body length of 9-12 inches long and
weighs 23-63 ounces. The scaly, vertically
flattened tail is 7-11 inches long. It has short
legs and big feet, a large head, and ears that are
almost invisible underneath the fur. Well adapted
to its aquatic lifestyle, the muskrat's hind feet
are partly webbed and fringed with
short stiff hairs. It is covered with
short, thick fur that is medium to dark brown or
black in color. The fur has two layers, which
helps protect them from cold water.
Muskrats have poorly
developed senses of sight, hearing, and smell.
They are affected by quick changes in
temperature, and dry, hot weather is especially
bad for them. A special adaptation called
regional heterothermia regulates the flow of
blood to the feet and tail, allowing these
structures to be cooler than the body core. Musk
glands at the base of the tail give this rodent
its common name.
Muskrats are found throughout
much of North America, from Alaska to
Newfoundland south to Baja California and South
Carolina. They have also been introduced into
several parts of Europe, for their fur.
Although they are found
in ponds, lakes, and swamps, their favorite
locations are marshes, where the water level
stays constant, preferably 4-6 feet deep. They
also require dense vegetation that
provides both food and cover. The only time they
are ever seen away from water is when they are
searching for new feeding grounds.
The presence of muskrats in an area is
shown by well-defined channels through the
vegetation, slides down banks, and networks of
tunnels. Muskrats can stay submerged for up to 12
minutes, and can swim both forwards and
Muskrats make two kinds of nests. In open
swamps a pile of aquatic vegetation is made that
is about 4 feet high and 5 feet across. The walls
are cemented with mud and a nest of finely
shredded leaves is made in the middle. Several
tunnels connect the nest with underwater exits.
The other type of nest is built along the edges
of ponds and rivers. The nest itself is a burrow
dug into the bank or shoreline, with several
entrances, both above the high water mark and
underwater. Above water entrances are camouflaged
with piles of vegetation.
Muskrats form large family groups and live in
definite territories. They continue to live in
large groups even when fighting and cannibalism
occur in high rates. They are active at all times
of the day, but most active from mid-afternoon
until just after dusk. Most communication is by
musk, which also is used as a warning for
intruders. They are capable of vocalizing by
squeaks and squeals, but are usually quiet.
In the northern parts of their
range, muskrats breed from spring to autumn, and
several families are raised during that time.
Breeding occurs year-round in the southern
ranges, but births peak between November and
Five to seven babies are born
per litter, after a gestation of 22-30 days.
Blind, naked, and helpless at birth, they can
swim when they are about ten days old, begin to
eat vegetation when they are about 20 days old,
and are fully weaned at about 30 days old. Upon
weaning they are driven out of the nest, which
will likely be occupied by a new litter soon
after. A single female may raise five litters a
year. Both sexes can mate at about one year of
age. Average lifespan is about three years.
Muskrats feed primarily on the roots and
leaves of aquatic plants (such as waterlilies,
wild rice, cattails, arrowheads, etc.), but will
also go after crops such as maize, alfalfa,
clover, and peanuts, and, occasionally, crayfish,
mussels, and fish. Although a muskrat can
close its mouth around its protruding teeth and
chew underwater, it usually drags its food out to
a feeding platform in the water or a feeding
station near one of its travel paths. These
feeding platforms are made of mud and vegetation.
genus & species Cynomys parvidens
Animal Diversity Web http://animaldiversity.org/accounts/Ondatra_zibethicus/
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