During the dry seasons, they frequent up to three permanent waterholes. Baboons rest at the waterholes during midafternoon and also dig drinking holes only a short distance from natural waterholes. Group organization The Hamadryas baboon has an unusual four-level social system called a multilevel society. Most social interaction occurs within small groups called one-male units or harems containing one male and up to 10 females, which the males lead and guard. A harem often includes a younger "follower" male that may be related to the leader. Two or more harems unite repeatedly to form clans. Within clans, males are close relatives of one another and have an age-related dominance hierarchy. Bands are the next level. Two to four clans form bands of up to 400 individuals which usually travel and sleep as a group. Males rarely leave their bands, and females are occasionally transferred or traded between bands by males. Bands may fight with one another over food or territory, and the adult male leaders of the units are the usual combatants. Bands also contain solitary males that are not harem leaders or followers and move freely within the band. Several bands may come together to form a troop, usually at sleeping cliffs. Group behavior The hamadryas baboon is unusual among baboon and macaque species in that its society is strictly patriarchal. The males limit the movements of the females, herding them with visual threats and grabbing or biting any that wander too far away. Males sometimes raid harems for females, resulting in aggressive fights. Many males succeed in taking a female from another's harem, called a "takeover". Visual threats are usually accompanied by these aggressive fights. This would include a quick flashing of the eyelids accompanied by a yawn to show off the teeth. As in many species, infant baboons are taken by the males as hostages during fights. However, males within the same clan tend to be related and respect the social bonds of their kin. In addition, females demonstrate definite preferences for certain males, and rival males heed these preferences. The less a female favors her harem males, the more likely she will be successfully taken by a rival. Young males, often "follower" males, may start their own harems by maneuvering immature females into following them. The male may also abduct a young female by force. Either way, the male will mate with the female when she