chest-beating: This behavior is done by all gorillas and the either one or two open-fist hands are clapped against the chest (Estes, 1991). Adult males produce a sound when doing this because of air sacs they have which are located on both sides of their throat (Estes, 1991). For the adult male this is a threat display (Estes, 1991).

strutting walk: This is a rigid walk with arms bowed and the hair bristled so that the individual looks bigger (Estes, 1991). The individual makes short steps and has the side facing the receiver and only looks at the receiver but for a few glances (Estes, 1991). This is a dominance display and is mainly performed by silver-back males especially when a lone silver-back is attempting to lure a female away from the group (Estes, 1991).

staring: This where the sender has its eyes fixed on the receiver, the eyebrows are lowered, the head is angled down, and the lips are parted and pursed (Estes, 1991). This communicates aggression or annoyance (Estes, 1991).

tense-mouth face: This is like staring but the gums and teeth are displayed having the lips curled back (Estes, 1991). This is a threat display for potential predators, mostly given by adult males, and is often accompanied by a mock charge and scream and roars (Estes, 1991).
Western Lowland Gorilla (adult male)

pout face: This is where the lips are pursed, mouth is slightly parted or compressed, and the eyebrows are raised (Estes, 1991). This is most often given by infants when their mothers leave them or they do not receive what they want, it is a display of light distress (Estes, 1991).

open-mouth grimace: This is where the mouth is wide open, the corners of the mouth are drawn back, the eyebrows are raised, the head is tilted back a little, and the eyes move back-and-forth (Estes, 1991). This is a fear display (Estes, 1991).

play face: This is where the mouth is open but not showing the teeth or gums (Estes, 1991). This is seen during play (Estes, 1991).

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