They vary in size and habits. Most are able to rise up on their hind legs and stand fully erect comfortably for long periods. This way they watch for predators. They tend to live together more than other squirrels, and many live in colonies with complex social structures. Most Marmotini are rather short-tailed and large squirrels. The Alpine marmot ("Marmota marmota") is the largest living member of the Sciuridae, at 53–73 cm in length and weighing 5–8 kg.