Reaching of the trunk to touch or near touch, or place into the mouth of another. Trunk-to-Mouth is a very common elephant behavior and occurs between elephants of all age/sex groups in a broad range of contexts.
In an Aggressive context Trunk-to-Mouth appears to be a Conciliatory gesture. In an Affiliative context between both relatives and non-relatives Trunk-to-Mouth as well as Reciprocal-Trunk-to-Mouth is observed during all manner of Greeting and Bonding situations.
In a Coalition Building context, Trunk-to-Mouth as well as Reciprocal-Trunk-to-Mouth is commonly observed when elephants bunch together to face off a common threat and appears to function in reinforcing bonds and reassuring one another.
In a Calf Reassurance & Protection context, Trunk-to-Mouth is a common component of Caressing behavior displayed by mothers and allomothers toward infants and calves during care, reassurance and protection. Mothers may also use Trunk-to-Mouth to get the attention of infants before moving off or in an attempt to Guide them toward or away from something. In some cases mothers use an exaggerated movement in which they touch the infant’s mouth and then drawing the infants head up and in the correct direction by sliding the along the underside of the infants trunk. A mother may also cover the mouth of a crying infant with her trunk fingers as if to console.
In a Calf Nourishment & Weaning context infants and calves use Trunk-to-Mouth to Solicit-Food from their mothers or others.
In a Social Play context Trunk-to-Mouth as well as Reciprocal-Trunk-to-Mouth is observed particularly during Sparring.
The above is a cursory description of one of the most quintessential elephant behaviors and much research is needed to understand the full function of this gentle gesture.
References: Douglas-Hamilton 1972: ch 6; Buss, Rasmussen & Smuts 1976; Moss 1981; Lee 1986; Lee 1987; Poole 1982; Poole 1996: 137; Rasmussen 1988; Poole & Granli 2003; Poole & Granli 2004; Poole & Granli 2011; O’Connell-Rodwell et al 2011 [Test-Mouth]. (Full reference list)
This behavior occurs in the following context(s): Advertisement & Attraction, Affiliative, Birth, Calf Reassurance & Protection, Coalition Building, Social Play