Chest-beating displays against outlying silverbacks can be intense but rarely develop into a confrontation. There are nine steps in the highly ritualized charge display from hooting to chest-beating to running and tearing plants to slapping the ground. Mutual grooming is not as common among gorillas as in other primates. It is often practiced between a mother and her offspring. Occasionally a female will groom the silverback but he seldom reciprocates.
Grooming helps keep the hair free from dirt and parasites and also reinforces social bonds.
D. Daily Activity Cycle. When the dominant silverback decides to settle in for the evening, each gorilla builds a new nest for the night. Nest counting is a reliable method for estimating populations densities since only mothers and infants share a nest.