The one-male unit is the reproductive core, a mantled male with one to about nine females and their young. He herds them, and a female that strays too far is threatened or bitten on the neck, a behaviour rare among other baboons.
Units whose males are often related form a clan and tend to forage in loose company. Several clans travel as a band, which is the functional daily group and defends access to water and food. At night, bands converge on the limited number of safe cliffs, forming sleeping troops that can exceed several hundred animals but that dissolve at dawn.
The layers are not fluid. Membership at the unit level is enforced by the male, while the band is the level at which coordination over movement happens. This is the same nested structure found in geladas and in snub-nosed monkeys, arrived at independently by lineages facing patchy resources and scarce safe sleeping sites.