Flexing part of the trunk to make it rigid, and using it as a crutch to steady, give support to, or buttress the body when an elephant is clambering up an embankment or up a steep incline or is moving carefully over unstable terrain. This extra support is often used at the top of an embankment when the forelegs of the elephant are bent (on wrists) and the weight of the head is tipped forward.
References: Poole & Granli 2021. (Full reference list)
This behavior occurs in the following context(s): Maintenance