As with the beaver—the only North American mammal whose engineering feats surpass the prairie dog’s—it is often difficult to distinguish instinctive behavior from actual problem solving. Burrow systems vary from individual to individual and with local topography. However, as early attempts to “drown out” prairie dogs soon proved, the overall design of their burrow networks minimizes the dangers of flooding. While the lower angle of the tunnel may fill with water, the portion of the burrow that culminates in the sealed escape hole serves as an air bell, preventing a further rise of water and protecting the animal from being flooded out of its sanctuary during periods of heavy rain. Not realizing that prairie dogs can live without water—as can many other plains mammals that manufacture metabolic water from foods they eat—instigators of attempts to drown out the animals concluded that the animals dug down to ground water. The myth of the “town well” persisted until well diggers discovered that the water table in most townsites was hundreds of meters down. More than once their burrows have saved them from talon and teeth, and they take care to maintain the mounds surrounding the entrances to their tunnels. These structures serve not only as watch-towers, but also as dikes against downpours that may temporarily turn a town into a lake. But even instinctive digging habits and well engineered burrows, by themselves, would not have permitted prairie dogs to achieve their once staggering population levels—estimated to have been about 25 _billion_ individuals. Only through the additional benefits of some form of social organization and an effective means of communication could such success have been attained. _continues on page 58_ Togetherness—Prairie Dog Style [Illustration: Prairie dogs.] [Illustration: A prairie dog sounds the alarm, alerting the whole town about an impending danger, such as a coyote, a ferret, or a person. The rest take up the call, and as the danger approaches each burrow the inhabitants duck underground. The others continue to stand erect and sound the warning. By listening carefully, those underground can track the location of the enemy. When two high-pitched notes are sounded, all rush for cover, for that means a hawk is overhead or nearby and there’s no time to wait and repeat the signal. After the danger has disappeared, a dog sounds a melodic whistle, and a few others repeat the all-clear before the usual activities of grooming, breeding, eating, and burrow building are resumed. Blacktails make at least seven other calls, but they mostly concern matters of interest to the coterie, or family, instead of to the whole town.]