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Table 2 Gesture and vocalisation types produced to initiate carries in chimpanzee mother–infant dyads identified in this and other studies on wild groups in Budongo (Hobaiter and Byrne 2011; Roberts et al. 2014a); Gombe (Goodall 1986) and Mahale (Nishida et al. 1999)

From: Should I stay or should I go? Initiation of joint travel in mother–infant dyads of two chimpanzee communities in the wild

Gesture/vocalisation Definition (this study) Used by Budongo Gombe Mahale
Audible
Loud scratch [ls] Signaller makes deliberate scratching movements on own body Mother Big loud scratch Self-scratch Scratch self signalling
Slap ground [sg] Signaller hits ground with flat palm of his hand Mother Slap object Slap ground Slap branch
Tactile
Arm on [ao] Signaller places palm on recipient’s back (>2 s) Infant Hand on
Shake back* [sb] Signaller shakes lower back in an upward movement when recipient is already clinging Mother
Scoop infant [rb] Signaller reaches behind himself and gently pushes infant up onto back with a back ward and upward movement Mother Scoop Scoop Scoop infant
Touch [to] Signaller makes short (>2 s) contact with recipient using palm and/or fingers Both Touch inner hand Touch Touch
Directed push [pu] Signaller uses limbs or body to bring recipient in direction of movement Mother Directed push Pull towards hand leading Push ahead
Pull [pl] Signaller moves recipient’s body part towards himself Both Pull Pull Pull
put ventral [pv] Signaller pushes recipient in ventral region Mother Put ventral
Visual
Backward sweep [bs] Signaller stretches arm towards behind himself in a short, rapid movement Mother Backward sweep Climb aboard
Extend leg [el] Signaller extends leg to facilitate climb onto self Mother Present leg Extend leg as ladder
Look [lo] Signaller gazes at recipient (>2 s) Both Look Wait Look; wait
Lower back [lr] Signaller, in lateral position to recipient, lowers abdomen without stopping locomotion Mother    
Stop and look back/down [lb/ld] Signaller stops with body orientated in direction of movement and looks back (or down) at recipient Both Look back
Present back/shoulder/venter [pb, ps, pv] Signaller offers back/venter to recipient Mother Present Present Present
Reach [ra] Signaller extends arm towards recipient Both Reach Extend hand Extend hand
Rear up* [ru] Signaller briefly rises straight up on two feet while positioned towards recipient Mother
Turn Bipedal* [tb| Signaller turns towards recipient with short bipedal movement Mother
Vocalisations
Hoo whimper [hoo] Signaller utters a series of soft, low pitch sounds that may become progressively louder and higher in pitch Infant Whimper Whimper
Soft grunt [sgr] Signaller utters a soft, barely voiced sound Mother Soft grunt Grunt