This species is actually the largest member of the family Sciuridae, which includes marmots, ground squirrels, prairie dogs, chipmunks, tree squirrels, and flying squirrels. Fossils from this family have been dated back to the Miocene. Two species that are similar to Marmota monax are the hoary marmot, Marmota caligata, and the arctic ground squirrel, Citellus columbianus. The hoary marmot is slightly larger body than the woodchuck, and also has a longer tail. The hoary marmot is also black and white on the head and shoulders, coloration that is absent on the woodchuck.
Hoary marmots live in high mountains near timberline, alpine meadows, and talus slopes.
The arctic ground squirrel is smaller than the woodchuck, and lives in regions of tundra. Coloring of the arctic ground squirrel is similar to the woodchuck, but the arctic ground squirrel lacks the woodchuck's black feet. Their total body length is generally 560 mm. The front feet have four clawed toes and a pollex with a flattened nail located a bit up the inside of the leg. The hind feet have five clawed toes.