The
ground squirrels are members of the
squirrel family of rodents (
Sciuridae) which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known as
marmots (genus
Marmota) or
prairie dogs, while the smaller and less bushy-tailed ground squirrels tend to be known as
chipmunks. Together, they make up the "marmot
tribe" of squirrels,
Marmotini, and the large and mainly ground squirrel
subfamily Xerinae, and containing six living genera. Well-known members of this largely
Holarctic group are the
marmots (
Marmota), including the American
groundhog, the
chipmunks, the
susliks (
Spermophilus), and the
prairie dogs (
Cynomys). They are highly variable in size and
habitus, but most are remarkably able to rise up on their hind legs and stand fully erect comfortably for prolonged periods. They also tend to be far more gregarious than other squirrels, and many live in colonies with complex social structures. Most Marmotini are rather short-tailed and large squirrels, and the
alpine marmot (
Marmota marmota) is the largest living member of the Sciuridae, at 53–73 cm in length and weighing 5–8 kg.