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Muskrats (Ondantra zibethicus) are large semi-aquatic rodents that reside in freshwater areas. The resemble beavers but are related to mice and rats. Muskrats get their common name from a strong-smell or musk that they produce during mating season and to mark territories.
Muskrats occur throughout Indiana but are most numerous in areas of abundant shallow water. The northeastern section of the state produces a substantial proportion of these rodents each year. The construction of private ponds for livestock watering or recreation across Indiana has been important in offsetting the losses of muskrat habitat due to wetland drainage and stream channelization.
Muskrats living on streams prefer to place nest chambers above water level in burrows entered from the water, in marshes and lakes, they use cattails and other aquatic plants to construct houses resembling small haystacks.
Courtship is conducted by the female as she swims about making noises similar to the squeak of a mouse. Two or three litters may be produced each year, but most muskrats in Indiana are born in May and June, 28 to 30 days after mating. Litters averaging about six in size are born in a shredded cattail or grass nest. The male assists in preparing the chamber, but does not enter the house or burrow after the young are born. Kits are naked, blind, and helpless at birth, but are weaned at 4 weeks of age. At this time, they can swim but do not dive well. If the mother is to have another litter soon, they are driven from the house or burrow, but the last litter of the season often spends the winter with its parents. Muskrats are quite tolerant of each other, and except during the breeding season, several may live together.
Many muskrats spend their entire lives within a few hundred yards of their birthplace, but in autumn and spring, some are forced to migrate to less-crowded areas and may wander several miles to establish new homes.
Muskrats are mostly vegetarians. They eat:
When vegetation is not available they eat:
Food is not stored for winter use, so they must dig roots and tubers from beneath the ice, returning to their house and burrow to feed. If food sources are too far from the house, a feeding shelter called a “push-up” is built on the ice. A similar feeding platform - a raft consisting of discarded plant food - is constructed for summer use.
A dense winter population feeding on roots and bulbs in a marsh or small lake may consume nearly all the roots. Upper parts decay the following spring, turning the water and soil sour so that few plants will grow in that area. This is called an eat-out, and if little water moves through it, this portion of the marsh may be unproductive for several years.
Resident landowners and tenants can trap or shoot a muskrat that is causing damage on their own property. The muskrat must be euthanized or released within the county of capture on property in which you have permission. In order to prevent the spread of disease, the DNR encourages homeowners to safely and humanely euthanize the muskrats, if possible. If you do not want to trap the muskrat yourself, contact a licensed nuisance wild animal control operator.
Muskrats can sometimes be prevented from digging in a pond dam or bank by rip-rapping. Drawing the pond down at least 2 feet below normal water levels during the winter can also encourage them to leave. Once it is drawn-down, you can trap or shoot (where legal) the muskrat, then fill the dens, burrows and runs and rip-rap the dam with stone.
Make a concentrated effort to reduce the breeding population of muskrats during the winter months through either trapping or shooting (where legal).
Muskrats are less trap-shy than most other furbearers. Baited or blind sets are effective capture methods. Traps need not be concealed, but drowning set should always be used. Small killer traps, such as the Conibear, placed at lodge entrances, bank dens or along runways are extremely effective and result in a substantial number of pelts.
Mortality is necessary to limit muskrats to a sustainable level. Trapping is one factor of mortality. Predators, disease and adverse weather alone may have little effect, but a combination of all three may be disastrous. Minks, raccoons, dogs and foxes normally take a few muskrats, but low water levels or starvation can expose these animals to heavy predation. Loss of water habitat from drainage projects is the primary cause of declining muskrat populations. Numerous diseases and parasites kill or weaken muskrats but assume importance only when living conditions are substandard. This usually occurs when populations rise beyond the ability of the area to support surplus individuals. Thus, the number surviving is adjusted to existing food supplies and living space.