By Josh Pike
Pagosa Wetland Partners
Throughout the Riverwalk wetlands, muskrats ramble, rustle and swim. Birds are perhaps the most recognizable residents of the wetlands, from blackbirds perched on the cattails near the 6th Street bridge to ducks paddling on the ponds near the Ross Aragon Community Center.
However, muskrats have a strong claim on being one of the most important organisms in the wetlands. In addition to their dynamic lifestyle and distinctive appearance, these 8- to 10-inch long mammals play a key role in maintaining the structure and health of the wetland through their voracious appetite for cattails.
The muskrat is a medium-sized North American rodent, the largest member of the subfamily arvicolinae, which contains 142 species, including all voles and lemmings and most types of North American mice. Outside of their size, muskrats are made distinctive by their thick fur and their long, scaly tails. Their fur coats have two layers, with the outer layer composed of long guard hairs protecting the thick and soft underfur from damage. This structure makes their fur warm and nearly waterproof, a key tool for surviving in the cold waters they spend much of their lives in.
Their tails, however, are completely hairless, being covered in scales. This tail is slightly flattened on its sides, a shape distinct to the muskrat, and is the animal’s primary tool for steering and propelling itself while swimming. While their brown fur and hairless tails may be reminiscent of beavers and their name suggests a connection to rats, in actuality, the muskrat is not closely related to either species.
Muskrats live almost exclusively in wetland areas like the Riverwalk wetlands and spend much of their time in the water, swimming and diving. Muskrats use their comfort in water and ability to swim to easily traverse the wetlands and find food. Additionally, to facilitate their movements, muskrats build cleared paths through the wetland plants and mud which they use year-round. Their diet is relatively wide-ranging, consisting primarily of aquatic plants, particularly cattails, supplemented by frogs and fish. Much of a muskrat’s feeding occurs at the site where the food is found. However, in the winter, they often bring food back to their dens to eat it in a dry and sheltered environment.
These large mud dens, called push ups, are evidence of the muskrat’s talent for building. A push up is typically built into the sides of a bank, where they carefully dig out an area. The muskrat then constructs a roof over this area using mud and vegetation, creating an enclosed space appropriate as both a wintertime shelter and the summertime refuge for young. Muskrats typically live in groups of a breeding male and female and their offspring.
The spring is consumed by fierce battles between muskrats for mates and living sites and the first young muskrats of the year are typically born in late spring or early summer. However, these young are unlikely to be the last, as muskrats, being prolific breeders, typically raise two to three broods of six to eight young every year. The young muskrats mature within a year and live for up to three years.
Among their unique qualities, it is the muskrat’s strong preference for cattails that makes them pivotal in shaping the ecology of the wetlands they inhabit. Cattails are rapidly growing plants that will quickly expand into every area of mud and shallow water within a wetland and choke out other wetland plants if left unchecked. However, the muskrat’s hunger for cattails is equally strong and their feeding can easily halt the expansion of cattails, preserving the stretches of open water upon which fish, insects and waterbirds rely. The paths they create through the wetlands also aid this function of maintaining sections of open water.
Muskrats are a major food source for many predators, including foxes and coyotes, hawks, eagles and owls. In this way, they support the community of predators in the wetlands who, in turn, prevent the muskrats from becoming too numerous and denuding the wetlands of vegetation. These crucial roles in controlling wetland vegetation growth and serving as a food source for predators make the muskrat a keystone species. In short, a keystone species is an organism with a disproportionately large impact on the ecosystem and one whose presence is necessary to retain its health. A wetland with a healthy muskrat population is often a healthy wetland, while one with either too many or too few muskrats is likely to suffer ill effects from an excess or deficit of aquatic plants.
Muskrats are relatively difficult animals for humans to observe, as they prefer to forage at dawn or dusk and are often inactive during the day. Additionally, even when active, they are often hidden within the cattails, foraging or swimming about. However, even though sighting a muskrat in the Riverwalk wetlands might be rare, the signs of their presence are easy to detect. Just look for the narrow channels carved through the reeds or to the areas of open water and you will see ample evidence that the local muskrat population is flourishing, performing their essential services while rambling through the wetlands.
If you want to learn more about the Riverwalk wetlands or get involved in protecting them and educating others about them, please contact Pagosa Wetland Partners at firstname.lastname@example.org or view us on Facebook at facebook.com/PagosaWetlands.