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Distribution & Abundance |
Habitat | Habits
| Foods |
Reproduction | Conservation
 The
muskrat is about the same size as a cottontail rabbit. Adults vary from 16 to 25
inches in total length and weigh from 1 1/2 to 4 pounds. The average weight is
about 2 1/2 pounds. Muskrats have small eyes and ears. The front legs are short
while the hind legs are longer, stronger and have partially webbed feet. The
black, scaly tail is flattened vertically (like the rudder of a ship) and is
almost as long as the body. The back is dark or chocolate brown and fades
gradually to a lighter brown with a reddish tinge on the sides. The underparts
are still lighter, shading to almost white on the throat.
Distribution & Abundance
Muskrats are common and live in every county in Illinois. Some of the
highest numbers are found in the northeastern and northwestern regions. Statewide, numbers are lower than they were 50 to 100 years ago
because of habitat loss caused by channelization (straightening) of streams,
drainage of wetlands and changes in stream flow caused by man-made drainage
systems under agricultural fields.
Muskrat populations can change greatly from year to year depending on weather
conditions and other factors. A bad winter, drought, flood or outbreak of
hemorrhagic plague can cause their numbers to plummet. However, they bounce back
quickly when conditions improve because they produce many young. Fall
populations can exceed eight muskrats per acre in good marsh habitats.
Habitat
Aquatic
habitats like rivers, streams, drainage ditches, marshes, lakes and ponds are
home to muskrats. Those that live in areas with shallow, stable water (like
marshes) often build dome-shaped houses by cutting and piling up cattails,
bulrushes or other aquatic vegetation. Some are 8 feet or more in diameter at
the base and have walls 1 to 2 feet thick. Tunnels angle upward from the underwater
entrances (usually two) to an inside chamber that's hollowed out above the water
level. This allows the muskrats to stay warm and dry in their nest chamber while
resting and raising their young. Similar but smaller houses with thinner walls
are built for resting and protection from predators while muskrats venture away
from their dwelling to look for food.
Muskrats that live in rivers, ditches and ponds usually don't build houses.
Instead, they burrow into the bank, beginning underwater and angling upward
until the tunnel clears the water level. Here they hollow out a living chamber.
Trails hollowed out by muskrats swimming in and out of their den entrances are
sometimes visible from above, especially along well-used travel routes. Burrows
dug into the dams of man-made ponds can wash out during high water, causing the
ponds to drain.
Habits
Muskrats are most active at night, but it's not uncommon to see one feeding
or building a house in the early morning or late afternoon. They spend most of
their time within a few hundred feet of their dens or houses. However, some move
away from their homes in late summer or early fall and can be seen traveling
through areas far from water. Similar overland movements can occur in the spring
during breeding season.
When populations get so high that food is in short supply, muskrats become
aggressive, often fight with one another, and sometimes eat their young. This is
one natural control that helps to balance muskrat numbers with their food
supply.
Foods
In marshes, muskrats eat the roots and stems of cattail, bulrush, arrowhead,
duckweed and water-lily. Clover, corn and grasses are common foods in
agricultural areas. Although they are considered to be herbivores
(plant-eaters), muskrats sometimes eat freshwater clams, snails, crayfish, fish
and frogs. Feeding piles or platforms of
shredded vegetation often accumulate where muskrats make a habit of stopping to
eat their meals.
Reproduction
The breeding season starts in late winter and ends in September. Pregnancy
averages 28 days. Females usually have two litters, sometimes three, per year. A
typical litter has four to seven young.
The young are blind, nearly helpless and practically naked at birth. By one
week of age they're covered with coarse gray-brown fur. Their eyes open between
14 and 16 days of age. About this time the young can swim, dive, and climb on
low, floating objects. They're weaned at 3 to 4 weeks, and can take care of
themselves at about one month of age. It's possible for young born in early
spring to breed in late summer, but most breed for the first time the spring
following their birth.
Conservation
Trapping is the best way to solve specific problems caused by muskrats (for
example, when they burrow in a pond dam) and manage their numbers for ecological
benefits. Trapping is allowed for only two to three months during the fall and winter so
that no babies or mothers with dependent young are taken. Wetland protection,
restoration and enhancement are important practices, especially in
fast-developing areas of northeastern Illinois where marshes were once abundant.
Filter strips (typically 30- to 60-foot-wide strips of grass planted along
streams and rivers) improve water quality, reduce erosion, stabilize
banks and provide food for muskrats.
Breaches in pond dams can be avoided by building the dam with a wide base and a
crest at least three feet above the water line. Dams that slope gently toward the
water are less prone to damage than those with a steep face. Fencing should be
used to keep livestock off the sides of the dam so that they don't cave-in
muskrat burrows that could weaken the dam. A thick layer of hand-sized rocks
dumped on the entire face of the dam can help to prevent erosion and discourage
burrowing. |
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Hunting and Trapping Furbearers
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