Opening the mouth. Covered by the trunk the mouths of elephants are not very obvious sources of visual displays, but during excited vocal interactions elephants open their mouths wide, often holding their trunks curved upward, exposing the mouth. During many social interactions elephants become highly aroused, opening their mouths to Rumble, Roar or scream at very high sound pressure levels. Typically, Open-Mouth indicates vocalization, but Open-Mouth is also observed during Sparring when elephants raise their trunks over the heads. Open-Mouth may also be observed during aggressive interactions, when an elephant, often an adult female, may hold her mouth open as she aggressively follows another. It is possible that she is producing a very low frequency vocalization, but often the mouth is held open for a longer time than would be typical of a Rumble. 

All age/sex groups may be observed displaying Open-Mouth, but it is much more common among female elephants than among males. Males might be observed exhibiting Open-Mouth when Roaring in protest in a Submissive context, while females show Open-Mouth in Affiliative, Aggressive, Movement Space & Leadership, Coalition Building, Birth, Advertisement & Attraction and Submission contexts. Infants and calves will exhibit Open-Mouth in a Calf Protection and Reassurance context.

References: Poole et al 1988; Poole 1996: 275; Poole & Granli 2003; Poole & Granli 2011 [Mouth-Opening]. (Full reference list)

This behavior occurs in the following context(s): Advertisement & Attraction, Affiliative, Aggressive, Birth, Calf Reassurance & Protection, Coalition Building, Submissive, Protest & Distress