Northern Prairie Wildlife Research Center
DISTRIBUTION: Statewide wherever permanent water is available. Most abundant in the prairie pothole region.
HABITAT: Muskrats prefer well-vegetated sloughs and lakes with a fairly stable water level. They are also found in creeks and rivers as well as in small potholes. Their existence in any area is dependent upon a year-round supply of water. When water areas go dry during the summer, the muskrats may move to another area. When potholes or sloughs freeze solidly to the bottom in winter, the muskrats will perish.
LIFE HISTORY: Muskrats raise more than one litter a year with the first litter usually born in late May or early June. In North Dakota muskrats usually have two litters and occasionally three. The gestation period of muskrats is 29 to 30 days. The average litter contains five or six young with litter sizes ranging from one to eleven. The young muskrats, blind and naked at birth, are raised either in a nest chamber within the muskrat house or in a den in the bank. They remain in the nest for three or four weeks when they move out to fend for themselves. Muskrats weigh less than an ounce at birth and grow rapidly, reaching adulthood in less than a year. Average adult muskrats weigh from two to two and a half pounds. Muskrats are somewhat active during the day but most of their activity takes place at night. They do not hibernate during the winter but live in relative comfort in their well constructed houses or in bank dens. Both their houses and dens have entrances under the water so even when the area is frozen over, they can swim about and gather roots and stalks of aquatic plants for food.
FOOD HABITS: Foliage, roots, and bulbs of aquatic plants such as cattail, bulrush, pondweeds, and sedges. Muskrats also eat corn and some other terrestrial plants when readily available and occasionally eat frogs, snails, and clams.
SUGGESTED BAITS: As muskrats normally have an abundance of food available, baits and lures are not as effective as for other species. However, apples and vegetables (especially carrots) are sometimes effective and are often used in under ice sets.
Most of North Dakota's trappers get their start by trapping the muskrat. Because muskrats are confined to a limited area of water, are easy to trap, and are abundant when water conditions are good, they are a good "break-in" species for the beginning trapper.
It is easy to determine if muskrats are present in a slough as their houses and runways are easily seen. They also build small mounds of vegetation which may be mistaken for unfinished houses. These are "feeders" and as the name implies, are used as feeding and resting places by the muskrats. They are commonly of two types; one kind is big enough so that the muskrat can come up inside it and feed, the other is nothing more than a platform upon which the muskrat can sit to eat or loaf.
You can also see other places where muskrats have been coming out of the water to rest or to eat. Look for their tracks and droppings along the shore. When muskrats feed, they often leave a scattering of pieces of partly eaten roots and stems of plants. Look also for floating pieces of vegetation which often mean that muskrats have been at work in that area.
In the fall, before freeze up, muskrats are usually caught in blind sets. They cannot feed under water and do not normally eat while in the water, but climb out on their houses or on feeders, along the shore, on rocks, or on logs or other floating objects to eat. Traps set in the water around places where muskrats go to feed are very effective. The trap should be from two to three inches below the water.
The "floating log" set is a good one for muskrats. Pieces of 2" x 10" plank about two feet long with a trap set in mud and loosely covered with debris can be used in place of a log. Secure the trap chain to the bottom of the plank and run a wire down to a rock or stake to keep the plank from floating away. Lure or bait can be used to good advantage at such a set.
Another good muskrat set can be made by securing a trap to a board (with nails or a cleat to hold it in place) and sticking the board in the slough bottom at an angle so that the muskrat would use it as a feeding or resting place. Push the board in far enough so it is good and solid and the trap is under the water. This set can also be baited although the muskrats will use it as a resting site even without bait or lure.
Muskrats that live in bank dens can be easily caught by setting a trap in the runway. Runways that are partially exposed and filled with from three to four inches of water are the best to trap in. If they are deeper than that, the 'rat will often swim right over the trap.
Muskrat trapping in North Dakota very often means trapping under the ice. The trapping season must be quite late to insure prime pelts and to give late litters time to grow up. Because our freeze up often comes early in the fall, the muskrat trapper will usually have to do at least part of his trapping through the ice.
Muskrats are easily caught after freeze up by trapping them in their houses. Be very sure that the ice is safe before venturing out on it! Each muskrat house has a main chamber in it. Tunnels from the main chamber lead to smaller "rooms" and to the main entrance which is constructed under the ice. Open the house carefully, using a hay knife or similar tool, and insert the trap. Place the trap on the floor of the chamber. Most trappers use a wire extension in the trap chain and wire it to a stick outside the house. Leave enough slack chain by the trap so that the muskrat can dive and drown itself. This type of set can also be used at the larger muskrat feeders with good results. Carefully replace the material taken out when opening the house and tamp it firmly back in place. This is very important! If you do not tightly close the hole you made in the side of the house, the house and its occupants will freeze.
When a water area is frozen, active muskrats bank dens can be easily located by looking for air bubbles under the ice. In runways that are being used, the activity of the 'rat often stirs up the mud, making the runway look cloudy. Cut a hole in the ice and set your trap in the runway. If the water is more than three inches deep, place the trap on some mud or grass or on a stone so that it is about three inches below the ice.
Other under ice sets can be made. The leaning board set can be used under the ice with the trap about eight inches below the ice and a bait fastened above the trap. Beaver type sets can be modified for trapping muskrats under the ice. A bait box set over a hole in the ice with a trap inside, can also be effective. Most such sets entail considerable effort and are no more effective than trapping in the house.
When the number of muskrats caught daily decreases considerably, it is time to pull up your traps. A good rule to follow when trapping muskrats in houses in this: count the number of muskrat houses (not feeders), multiply by five for a population estimate and quit trapping when you have taken seventy-five per cent of the estimated population. This will reduce the population down to a level where there will be plenty of breeding stock left and will insure enough room for good production the following summer.
Muskrat traps should be set so the muskrat will drown. Otherwise, they will wring off their foot, escape and die. If the water is not deep enough for drowning set, use "stop-loss" or "sure-hold" traps or the new humane traps. Be sure to check your muskrat traps regularly. Most trappers check them every few hours. This not only will enable you to prevent some animals from escaping, but it will also increase your catch, since a sprung trap, or one with a muskrat in it obviously cannot catch another until it is reset. Live muskrats in a trap can easily be killed by a sharp rap on the nose with a stout stick.
Muskrat pelts are handled as cased skins with the feet and tail cut off. Brush and clean the fur before skinning, remove excess fat from the skin and stretch the pelt carefully. Stretch your pelts uniformly and do not over-stretch them. A basic muskrat stretcher is eighteen inches long, eight and one-half inches wide at the base, tapering to five inches wide one foot from the base and down to a rounded end. Many trappers use commercial wire stretchers which insure uniformly stretched pelts.
Some fur buyers pay as much for unskinned muskrats as they do for prepared pelts. By doing this, they are assured of having well prepared, uniform pelts. They sell the carcasses to pay for their work in skinning. Check on this with your fur buyer before the season starts. If you do your own skinning, look for a market for the carcasses as selling them would increase your profit. Muskrat carcasses are sometimes used for mink food or sold to rendering plants.