Muskrats are common semi-aquatic rodents found across North America, and as introduced species in parts of Europe and Asia. They inhabit various wetland environments like marshes, ponds, and slow-moving rivers.
Distinctive Features
Muskrats possess physical attributes that suit their aquatic lifestyle. Adults typically weigh between 0.6 and 2 kilograms (1.3 to 4.5 pounds) and have a body length of 20 to 35 centimeters (8 to 14 inches), not including their tail. Their fur is short and dense, ranging from medium to dark brown on the upper body and lighter on the belly. This fur has two layers: a soft, thick underfur for insulation and longer, coarser guard hairs that provide waterproofing, allowing them to stay warm and buoyant.
A defining characteristic is their long, scaly, nearly hairless tail, 8-12 inches long. This tail is vertically flattened, serving as a rudder for swimming and a prop on land. Large, partially webbed hind feet provide primary propulsion in water. Conversely, smaller, agile front feet are suited for digging and holding food. Their eyes and ears are small and almost hidden by dense fur.
Life in the Water
Muskrats prefer habitats like wetlands, marshes, ponds, and slow-moving streams. They construct their homes in two primary ways. In shallow waters, they build dome-shaped lodges from vegetation like cattails and reeds, cemented with mud. These lodges feature underwater entrances leading to dry living chambers situated above the water line.
Muskrats also dig burrows into river or pond banks. These burrows have underwater entrances that ascend to dry nesting chambers, some extending up to 25 feet. They are excellent swimmers and divers, able to remain submerged for up to 20 minutes.
Diet and Daily Activities
Muskrats are primarily herbivorous, with plant material making up about 95% of their diet. They commonly consume aquatic vegetation such as cattails, water lilies, sedges, rushes, and pondweeds. They occasionally supplement their diet with small aquatic animals like freshwater mussels, crayfish, frogs, fish, small turtles, and snails.
They forage by cutting and eating vegetation, sometimes constructing feeding platforms. Muskrats do not store food for winter, relying on fresh plants year-round. They are most active during dawn and dusk, a pattern known as crepuscular activity. They can also be seen at night or, less frequently, during the day, especially in spring or winter.
Muskrats and Their Environment
Muskrats play a role within their wetland ecosystems. By consuming aquatic vegetation, they help maintain open water channels, benefiting wildlife like waterfowl and other bird species. Their feeding habits can significantly influence wetland vegetation structure.
Muskrats are prolific breeders, with females capable of producing two to four litters annually. Each litter typically contains an average of five to eight young. The gestation period is 28-30 days, and young develop rapidly. Populations naturally experience cycles of increase and dramatic decline, typically over six to ten years.
Humans have interacted with muskrats for centuries, notably through fur trapping for their thick and durable pelts. While valuable, muskrats can also pose challenges. Their burrowing activities can damage human infrastructure like pond dams, levees, and other water-retaining structures, potentially causing erosion or leaks. They may also occasionally feed on agricultural crops.