Spend a Day With the World’s Only Grass-Eating Monkeys | National Geographic
A day in the life for all geladas begins on the edges of the cliff. In the morning, they wake up with the sunrise and slowly ascend kind of to the edge of the high plateau.
They'll spend an hour, or maybe more, socializing with each other—grooming, having fun times, napping. Then the juveniles go off in flight. Once the kind of social period and morning is finished, they begin a daily ranging pattern where they'll walk inland as a big group, eating grass and herbs.
They want to spend a lot of their time, when they're not feeding, building social relationships with each other. What that means is that they spend a lot of time grooming one another, particularly in different pairs.
Then, as the day proceeds, they look back around at night. Geladas are vulnerable to predation, and so to avoid potential threats from hyenas or even leopards, they spend their nights sleeping perched on cliffs that overhang the greatest valley.
By dusk, they're grooming and then socializing a little bit before they go over the edge of the cliff for tonight's issues.