prairie fires, burrows provide important protection. Burrows help prairie dogs control their body temperature (thermoregulation) as they are during the winter and in the summer. Prairie dog tunnel systems channel rainwater into the water table which prevents runoff and erosion, and can also change the composition of the soil in a region by reversing soil compaction that can result from cattle grazing. Prairie dog burrows are long and below the ground. The entrance holes are generally in diameter. Prairie dog burrows can have up to six entrances. Sometimes the entrances are simply flat holes in the ground, while at other times they are surrounded by mounds of soil either left as piles or hard packed. Some mounds, known as dome craters, can be as high as high. Other mounds, known as rim craters, can be as high as . Dome craters and rim craters serve as observation posts used by the animals to watch for predators. They also protect the burrows from flooding. The holes also possibly provide ventilation as the air enters through the dome crater and leaves through the rim crater, causing a breeze though the burrow. Prairie dog burrows contain chambers to provide certain functions. They have nursery chambers for their young, chambers for night, and chambers for the winter. They also contain air chambers that may function to protect the burrow from flooding and a listening post for predators. When hiding from predators, prairie dogs use less-deep chambers that are usually below the surface. Nursery chambers tend to be deeper, being below the surface. Social organization and spacing Highly social, prairie dogs live in large colonies or "towns" and collections of prairie dog families that can span hundreds of acres. The prairie dog family groups are the most basic units of its society. Members of a family group inhabit the same territory. Family groups of black-tailed and Mexican prairie dogs are called "coteries", while "clans" is used to describe family groups of white-tailed, Gunnison’s, and Utah prairie dogs. Although these two family groups are similar, coteries tend to be more closely knit than clans. Members of a family group interact through oral contact or "kissing" and grooming one another. They do not perform these behaviors with prairie dogs from other family groups. A prairie dog town may contain 15–26 family groups. There may also be subgroups within a town, called "wards", which are separated by a