How Big Can a Muskrat Get? Dimensions & Key Traits

Muskrats are semi-aquatic rodents native to North America, found in wetlands, marshes, rivers, and ponds across Canada, the United States, and parts of Mexico. Though often mistaken for rats or smaller beavers, muskrats are distinct mammals well-adapted to aquatic life, where they are skilled swimmers.

Understanding Muskrat Dimensions

Muskrats are medium-sized rodents, significantly larger than typical rats but considerably smaller than beavers. An adult muskrat typically weighs between 1.5 to 4.5 pounds (0.7 to 2 kg), with some individuals reaching up to 5 pounds. This weight range is about four times that of a common brown rat.

The body length of a muskrat, excluding its tail, generally ranges from 8 to 15 inches (20 to 38 cm). Including the tail, their total length can be between 16 to 28 inches (40 to 70 cm), with the tail itself measuring 7 to 12 inches (18 to 30.5 cm). In contrast, beavers can weigh 35 to 65 pounds and measure 39 to 47 inches long, highlighting the significant size difference.

Distinctive Physical Traits

Muskrats possess several physical characteristics that enable their semi-aquatic lifestyle and distinguish them from other rodents. Their fur is dense and thick, typically ranging from medium to dark brown with lighter shades on the belly.

This fur has two layers: a soft, dense underfur that traps air for insulation and buoyancy, and longer, glossy guard hairs that provide waterproofing. The color of their fur can vary seasonally and geographically, sometimes appearing reddish-brown or nearly black.

The muskrat’s tail is a unique and defining feature. It is long, sparsely haired, and covered in scales rather than dense fur. The tail is vertically flattened or laterally compressed, contrasting with a beaver’s wide, horizontally flattened tail or a common rat’s round tail. This flattened shape functions primarily as a rudder for steering in water, also providing some propulsion. On land, their tails often drag, leaving a recognizable trail.

Muskrats have hind feet that are partially webbed and considerably larger than their front feet, serving as the main means of propulsion for swimming. Stiff hairs on their toes further aid in paddling through water. Their smaller front feet are adapted for digging and holding food. Their prominent incisors are typically light orange to yellow. These chisel-like front teeth grow continuously and are used for cutting through aquatic vegetation.