Muskrats and Mink

Mammal Marvels of the Marsh

Wetlands are important places for mammals, too. We usually think of beaver as important wetland builders. Indeed they are, cutting trees with their sharp frount teeth to dam a stream, slowing down the water to flood an area and creating a small wetland pond.

But prairie potholes are more often home for two other mammals, the muskrat and the mink.

Like the beaver, muskrats are rodents. They are herbivores (plant-eaters) and depend on the roots, shoots, and leaves of wetland plants for food and lodging. Though they may burrow into dirt banks, muskrats usually build dome-shaped homes of plants, especially cattails and bulrushes. The domes may be over 3 feet high and up to 9 feet wide. Whether a muskrat home is a bank den or a marsh plant house, the entrance is always underwater. During the winter, they "eat themselves out of house and home." Muskrats eat the walls of their plant houses from the inside out!

Their webbed back feet help them to be excellent swimmers. Eyes located on top of their heads allow them to see while swimming, though they are rather near-sighted. The muskrat's tail is covered with scales instead of fur. It is flattened vertically (the opposite of a beaver's which lies flat upon the ground or water). Muskrats use their tails as rudders to help them steer through the water.

Their sharp front teeth (incisors) grow constantly and wear at an angle. This helps the teeth stay long enough and sharp enough to cut the tough wetland plants.

Muskrats breed several times each year, having 3-9 young in each litter. You can see how the numbers of muskrats (the population) could build up quickly. When there are too many muskrats in a wetland, they can and sometimes do eat too many of the wetland plants. The wetland becomes more open, depriving it of the cover of wetland plants. Muskrats must then move or die, because there is nothing more for them to eat.

Fortunately, wetlands have some predators to help control muskrat populations. People often trap muskrats for their fur, which helps to keep muskrat populations at levels where they don't eat-out the wetland.

Mink are also an important predator on muskrats. These sleek, beautiful animals are members of the family of animals we call Mustelids. All members of the family have special glands that give off strong smells. Yes, skunks are relatives of the mink. So, too, are weasels, ferrets, marten, fisher, otters, badgers, and wolverines.

Like all Mustelids, mink are carnivores. They are intelligent predators, using their keen sense of smell and sharp eyesight to detect their prey. Like all predators, mink are opportunists, taking almost any kind of available prey--birds, mice, fish, turles, crayfish, frogs, and snakes. But among their favorite prey are muskrats. They often dig into the muskrat houses during the fall and winter, or swim after muskrats in the spring and summer. Mink are good swimmers and can sneak up on the near-sighted muskrat.

Mink use stream banks or rock or log piles for dens. Often they will occupy the former dens of muskrats they've just had for dinner!

Muskrat and mink are two important mammals of the prairie potholes. Without the wetlands, these interesting and important species would be gone from the prairies.