Colonies fragment if the breeding female dies, with most surviving members dispersing to new locations. Particularly large individuals may also leave the colony to establish a new burrow system. In such cases, dispersal usually only occurs during rainy weather, ensuring that digging will be relatively easy once a suitable location has been found. New colonies are established by unrelated males and females, which become the new breeding pair. Dispersing individuals travel above ground, and are therefore vulnerable to predation from a wide range of animals; some studies have shown that only around 10 percent of dispersing individuals are later found in new colonies. For example, while small groups of siblings may sometimes leave a burrow system at the same time, normally only one survives to found a new colony.