Sucking on own trunk. Appears to be done when unsure, apparently for comfort. Infants and calves are typically observed exhibiting this display, but older elephants may also be observed to Trunk-Suck.
References: Kahl & Armstrong 2000; Poole & Granli 2003; Poole & Granli 2011. (Full reference list)
This behavior occurs in the following context(s): Ambivalent, Attentive, Foraging & Comfort Technique, Lone & Object Play, Social Play, Vigilance