Black-tailed prairie dogs live in huge colonies, known as towns, covering several hundred hectares. The largest prairie dog town ever found was in western Texas. About 160km wide and 400km long, and covering an area the size of Belgium, the town was home to an estimated 400 million prairie dogs. The burrow system is complex, the first tunnel going straight down for about 4.5m providing a quick escape from predators. Throughout the town there are escape hatches - tunnels built up to within a few inches of the surface - to be used in case of flooding.