copulation. Goodalls Copulation scream. Bonobos emit similar call. See video. squeeze Compress contents of mouth by pushing chin upwards. Hand or arms pressed against chin to facilitate wadging. See also wadge. Also in bonobos. See video. staccato call Newborn emits call in response to mothers sudden movement, approach by others, noises in surroundings, etc. Plooijs Staccato. See video. stalk Approach stealthily to prey or other chimpanzees, especially neighbors. Absent in bonobos. stamp Goodall: Forceful downward kick of one foot, or alternate feet. In charging displays, The chimp stamps his feet one after the other as he runs along. One foot is often stamped harder than the other. A standing chimp may stamp alternate feet.A sitting chimp may stamp several times with one foot. van Hooffs Stamp. Plooijs Stamp.