The basic unit of gelada society is the unimale family group, consisting of one male and several females and their young (6). Associated unimale groups cluster into bands that may travel in the same area, although membership is flexible and unimale groups have been known to travel with several different bands at different times or even alone (6) (7). Bands in turn aggregate in large temporary herds that come together usually during the dry season for grazing (6) (7). Outside of these social organisations are all-male bachelor groups, which forage on their own and sleep separately from the unimale groups (6) (7). Males from bachelor groups will challenge males of unimale groups for tenure of their harem, and thereby access to breeding females. Within unimale groups, female bonds are very strong, and the females will try to stay together even if the male of their group dies (6).
There is no defined breeding season, but a birth peak has been noted during the rainy season. Females usually give birth to a single infant at a time, after a gestation of five to six months. Females attain sexual maturity at around four or five years of age, whereas it takes five to seven years for males to fully mature (7).
The diet of the gelada depends on seasonal availability, but consists largely of grasses, with the blades, seeds and bulbs all being eaten (6) (7). Grasses are picked by rapid, dextrous hand movements as the gelada sits and shuffles along the ground (8), but the species is also reported to eat fruit, flowers, leaves, insects (6) and even small mammals (2).